ε Aurigae Special Editionsouthscienceandgerman.weebly.com/uploads/8/4/6/9/8469541/jaavso... ·...

The Journal of the American Association

JAAVSO Volume 40Number 2

2012

of Variable Star Observers

49 Bay State RoadCambridge, MA 02138

U. S. A.

ε Aurigae Special Edition

Also in this issue...• BVRI photometry of SN 2011fe in M101

• The 1909 outburst of RT Ser

• Photometry and spectroscopy of P Cygni

• A W UMa system with complete eclipses

• MP Gem—an EB with a very long period?Complete table of contents inside...

Historic first: 1.6-m wavelength image of ε Aur, 2009 Nov. 2, as initially processed by John Monnier, based on four telescope beam combination data acquired by MIRC at the CHARA Array and showing the shadow of the disk crossing the face of ε Aur. see page 618

Image courtesy of John Monnier, Univ. Michigan

Editorial BoardGeoffrey C. ClaytonLouisiana State UniversityBaton Rouge, Louisiana

Edward F. GuinanVillanova UniversityVillanova, Pennsylvania

Pamela KilmartinUniversity of CanterburyChristchurch, New Zealand

Laszlo KissKonkoly ObservatoryBudapest, Hungary

Paula SzkodyUniversity of WashingtonSeattle, Washington

The Journal of the American Association of Variable Star Observers

The Council of the American Association of Variable Star Observers2011–2012

Director Arne A. Henden President Mario E. Motta Past President Jaime R. García 1st Vice President Jennifer Sokoloski Secretary Gary Walker Treasurer Gary W. Billings (term ended May 2012) Treasurer Timothy Hager

Councilors

Editor John R. Percy University of TorontoToronto, Ontario, Canada

Associate EditorElizabeth O. Waagen

Assistant Editor Matthew R. Templeton

Production EditorMichael Saladyga

Matthew R. TempletonAAVSO

Douglas L. WelchMcMaster UniversityHamilton, Ontario, Canada

David B. WilliamsWhitestown, Indiana

Thomas R. WilliamsHouston, Texas

Lee Anne WillsonIowa State UniversityAmes, Iowa

ISSN 0271-9053

Edward F. GuinanRoger S. KolmanChryssa KouveliotouArlo U. Landolt

John MartinDonn R. StarkeyRobert J. StineDavid G. Turner

JAAVSOThe Journal of

The American Associationof Variable Star Observers

49 Bay State RoadCambridge, MA 02138

U. S. A.

Volume 40 Number 2

2012

ISSN 0271-9053

ε Aurigae Special Edition

The Journal of the American Association of Variable Star Observers is a refereed scientific journal published by the American Association of Variable Star Observers, 49 Bay State Road, Cambridge, Massachusetts 02138, USA. The Journal is made available to all AAVSO members and subscribers.

In order to speed the dissemination of scientific results, selected papers that have been refereed and accepted for publication in the Journal will be posted on the internet at the eJAAVSO website as soon as they have been typeset and edited. These electronic representations of the JAAVSO articles are automatically indexed and included in the NASA Astrophysics Data System (ADS). eJAAVSO papers may be referenced as J. Amer. Assoc. Var. Star Obs., in press, until they appear in the concatonated electronic issue of JAAVSO. The Journal cannot supply reprints of papers.

Page Charges

Unsolicited papers by non-Members will be assessed a charge of $15 per published page.

Instructions for Submissions

The Journal welcomes papers from all persons concerned with the study of variable stars and topics specifically related to variability. All manuscripts should be written in a style designed to provide clear expositions of the topic. Contributors are strongly encouraged to submit digitized text in ms word, latex+postscript, or plain-text format. Manuscripts may be mailed electronically to [email protected] or submitted by postal mail to JAAVSO, 49 Bay State Road, Cambridge, MA 02138, USA.

Manuscripts must be submitted according to the following guidelines, or they will be returned to the author for correction: Manuscripts must be: 1) original, unpublished material; 2) written in English; 3) accompanied by an abstract of no more than 100 words. 4) not more than 2,500–3,000 words in length (10–12 pages double-spaced).

Figures for publication must: 1) be camera-ready or in a high-contrast, high-resolution, standard digitized image format; 2) have all coordinates labeled with division marks on all four sides;

3) be accompanied by a caption that clearly explains all symbols and significance, so that the reader can understand the figure without reference to the text.

Maximum published figure space is 4.5” by 7”. When submitting original figures, be sure to allow for reduction in size by making all symbols and letters sufficiently large.

Photographs and halftone images will be considered for publication if they directly illustrate the text. Tables should be: 1) provided separate from the main body of the text; 2) numbered sequentially and referred to by Arabic number in the text, e.g., Table 1.

References: 1) References should relate directly to the text.

2) References should be keyed into the text with the author’s last name and the year of publication, e.g., (Smith 1974; Jones 1974) or Smith (1974) and Jones (1974).

3) In the case of three or more joint authors, the text reference should be written as follows: (Smith et al. 1976).

4) All references must be listed at the end of the text in alphabetical order by the author’s last name and the year of publication, according to the following format:

Brown, J., and Green, E. B. 1974, Astrophys. J., 200, 765. Thomas, K. 1982, Phys. Report, 33, 96. 5) Abbreviations used in references should be based on recent issues of the Journal or the listing provided

at the beginning of Astronomy and Astrophysics Abstracts (Springer-Verlag).

Miscellaneous:1) Equations should be written on a separate line and given a sequential Arabic number in parentheses

near the right-hand margin. Equations should be referred to in the text as, e.g., equation (1).2) Magnitude will be assumed to be visual unless otherwise specified.3) Manuscripts may be submitted to referees for review without obligation of publication.

© 2012 The American Association of Variable Star Observers. All rights reserved.

Journal of the American Association of Variable Star ObserversVolume 40, Number 2, 2012

Table of Contents continued on following pages

e Aurigae Special Edition

Highlighting ε Aurigae and Citizen Sky John R. Percy 609

ε Aurigae Papers

The Origins and Future of the Citizen Sky Project Aaron Price, Rebecca Turner, Robert E. Stencel, Brian K. Kloppenborg, Arne A. Henden 614

ε Aurigae—an Overview of the 2009–2011 Eclipse Campaign Results Robert E. Stencel 618

The International ε Aurigae Campaign 2009 Photometry Report Jeffrey L. Hopkins 633

An Analysis of the Long-term Photometric Behavior of ε Aurigae Brian K. Kloppenborg, Jeffrey L. Hopkins, Robert E. Stencel 647

V-band Light Curve Analysis of ε Aurigae During the 2009–2011 Eclipse Thomas Karlsson 668

Report From the ε Aurigae Campaign in Greece Grigoris Maravelias, Emmanuel Kardasis, Iakovos-Marios Strikis, Byron Georgalas, Maria Koutoulaki 679

Photoelectric Photometry of ε Aurigae During the 2009–2011 Eclipse Season Frank J. Melillo 695

Small Telescope Infrared Photometry of the ε Aurigae Eclipse Thomas P. Rutherford 704

UV-Blue (CCD) and Historic (Photographic) Spectra of ε Aurigae—Summary R. Elizabeth Griffin, Robert E. Stencel 714

Ha Spectral Monitoring of ε Aurigae 2009–2011 Eclipse Benjamin Mauclaire, Christian Buil, Thierry Garrel, Robin Leadbeater, Alain Lopez 718

High Cadence Measurement of Neutral Sodium and Potassium Absorption During the 2009–2011 Eclipse of ε Aurigae Robin Leadbeater, Christian Buil, Thierry Garrel, Stanley A. Gorodenski, Torsten Hansen, Lothar Schanne, Robert E. Stencel, Berthold Stober, Olivier Thizy 729

Spectroscopic Results From Blue Hills Observatory of the 2009–2011 Eclipse of ε Aurigae Stanley A. Gorodenski 743

Eclipse Spectropolarimetry of the ε Aurigae System Kathleen M. Geise, Robert E. Stencel, Nadine Manset, David Harrington, Jeffrey Kuhn 767

Table of Contents continued on next page

Polarimetry of ε Aurigae, From November 2009 to January 2012 Gary M. Cole 787

Modeling the Disk in the ε Aurigae System: a Brief Review With Proposed Numerical Solutions Richard L. Pearson, III, Robert E. Stencel 802

A Demonstration of Accurate Wide-field V-band Photometry Using a Consumer-grade DSLR Camera Brian K. Kloppenborg, Roger Pieri, Heinz-Bernd Eggenstein, Grigoris Maravelias, Tom Pearson 815

Stellar Photometry With DSLR: Benchmark of Two Color Correction Techniques Toward Johnson's VJ and Tycho VT Roger Pieri 834

Algorithms + Observations = VStar David Benn 852

An Artist’s Note on Art in Science Nico Camargo 867

JAAVSO Volume 40, Number 2—other papers received

BVRI Photometry of SN 2011fe in M101 Michael W. Richmond, Horace A. Smith 872

New Light Curve for the 1909 Outburst of RT Serpentis Grant Luberda, Wayne Osborn 887

International Observing Campaign: Photometry and Spectroscopy of P Cygni Ernst Pollmann, Thilo Bauer 894

The Pulsation Period of the Hot Hydrogen-Deficient Star MV Sagittarii John R. Percy, Rong Fu 900

GEOS RR Lyrae Survey: Blazhko Period Measurement of Three RRab Stars— CX Lyrae, NU Aurigae, and VY Coronae Borealis Pierre de Ponthière, Jean–François Le Borgne, F. Fumagalli, Franz–Josef Hambsch, Tom Krajci, J–M. Llapasset, Kenneth Menzies, Marco Nobile, Richard Sabo 904

Recent Maxima of 55 Short Period Pulsating Stars Gerard Samolyk 923

The Ross Variable Stars Revisited. II Wayne Osborn, O. Frank Mills 929

GSC 4552-1643: a W UMa System With Complete Eclipses Dirk Terrell, John Gross 941

VSX J071108.7+695227: a Newly Discovered Short-period Eclipsing Binary Mario Damasso, Davide Cenadelli, Paolo Calcidese, Luca Borsato, Valentina Granata, Valerio Nascimbeni 945

Variability Type Determination and High Precision Ephemeris for NSVS 7606408 Riccardo Furgoni 955

Is MP Geminorum an Eclipsing Binary With a Very Long Period? Dietmar Böhme 973

Recent Minima of 150 Eclipsing Binary Stars Gerard Samolyk 975

The Variable Stars South Eclipsing Binary Database Tom Richards 983

A Note on the Variability of V538 Cassiopeiae Gustav Holmberg 986

A Practical Approach to Transforming Magnitudes onto a Standard Photometric System David Boyd 990

ROAD (Remote Observatory Atacama Desert): Intensive Observations of Variable Stars Franz-Josef Hambsch 1003

The AAVSO 2011 Demographic and Background Survey Aaron Price, Kevin B. Paxson 1010

The Citation of Manuscripts Which Have Appeared in JAAVSO Arlo U. Landolt 1032

Abstracts of Papers and Posters Presented at the Joint Meeting of the Society for Astronomical Sciences and the American Association of Variable Star Observers (AAVSO 101st Spring Meeting), Held in Big Bear Lake, California, May 22–24, 2012

Fast Spectrometer Construction and Testing John Menke 1037

Observations Using a Bespoke Medium Resolution Fast Spectrograph John Menke 1037

Enhancing the Educational Astronomical Experience of Non-Science Majors With the Use of an iPad and Telescope Robert M. Gill, Michael J. Burin 1037

The Rotational Period of the Sun Using the Doppler Shift of the Ha Spectral Line Robert M. Gill 1038

A Single Beam Polarimeter (Poster) Jerry D. Horne 1038

Index to Volume 40 1039

Percy, JAAVSO Volume 40, 2012 609

Highlighting ε Aurigae and Citizen Sky

John R. PercyDepartment of Astronomy and Astrophysics, University of Toronto, Toronto. ON M5S 3H4, Canada; [email protected]

WelcometothisspecialissueoftheJournal of the American Association of Variable Star Observers,featuringpapersoneAurigaeandtheCitizenSkyproject (www.citizensky.org). As Price et al. explain in the opening paper,Citizen Sky grew out of International Year of Astronomy 2009, brilliantlypiggybackingontheinternationalcampaigntoobservethe2009–2011eclipseofabrightbutmysteriousstar.Itincorporatedthe“citizenastronomy”philosophyon which the AAVSO is founded—skilled volunteers participating in andadvancing astronomical research. Itwas a complexmultidisciplinaryprojectwhichrequiredcarefulorganization,facilitatedbyagenerousgrantfromtheNationalScienceFoundation.Thepapersinthisissuerepresenttheculminationoftheastronomicalresearchaspectsoftheprojectbut,asPriceet al.explain,thereweremanyotherpositiveoutcomesoftheprojectwhich,wehope,willcontinuetobearfruitinthefuture.Inparticular,itprovidesanexcellentmodelforhowtoorganizeandmanageacomplexproject,andevaluatetheresults—somethingwhichisrarelydone. I’ve been actively involved in astronomical research for exactly halfacentury,soIhaveexperienced threeeclipsesofeAurigae(if I include the1955–1957onewhichIreadaboutasagraduatestudent).Iwaseducatedinanastronomydepartment(attheUniversityofToronto)whichhadspecialexpertiseinvariableandbinarystars—ofwhicheAurigaeisaprominentexample.Ihaveaspecificinterestintheintrinsicvariabilityofthesupergiantcomponentofthesystemso,unlikemanyobservers,Idon’thavetowaitfortheeclipseseverytwenty-sevenyears.Whatfascinatesmeaboutthepapersinthisissue,andinCitizenSkyingeneral, ishowtheyillustratesomanydiverseandintriguingfacetsofvariablestarastronomy. Firstandforemost:eAurigaeisagenuineastronomicalmystery.Itconsistsof a pulsating blue supergiant and a secondary component, in a 9,896-day(27.09-year)orbit.Thesecondarycomponentissurroundedbyadonut-shapeddiskofgasanddust,whicheclipsestheprimarycomponentforalmostexactlytwoyearseachorbit.Itisstillnotclearwhethertheprimaryisanormalmassivesupergiant,inwhichcasethesecondaryismostlikelyapairofstarsincloseorbit(the“high-massmodel”),orwhethertheprimaryisalow-masssupergiant,and thesecondary isasinglestar (the“low-massmodel”).Wehope that thepapersinthisspecialissuewillhelptoresolvethismystery.ForanexcellentoverviewofeAurigaepriortothe2009–2011eclipse,seeTempleton(2008). Thisisfrontierastronomy.Disksofgasanddustarewidelystudied,becausetheyareubiquitous in theuniverse.Theyare foundaroundformingstars, in

Percy, JAAVSO Volume 40, 2012610

cataclysmicbinarysystems,andaroundsupermassiveblackholesatthenucleiof galaxies. Binary and multiple star evolution is poorly understood, eventhoughbinaryandmultiplestarsarethenorm,nottheexception.Itisatopicwhichisrelevanttosomeofthemostexcitingtopicsinastrophysicstoday.TheoriginofTypeIasupernovae,whicharethemostimportant“measuringsticks”inmoderncosmology,isoneexample. eAurigae has an apparentV magnitude of about 3.0—not much fainterthanthestarsintheBigDipper—soit isvisibleevenincitiessuchasmine.Beginningskywatcherstendtothinkthatallstarsarethesameso,atstarparties,Iliketotellthemabouttheparticularcharacteristicsofindividualbrightstars,especially bizarre stars such as eAurigae. Beginning skywatchers can thenbecomebeginningobservers;eAurigaeiseasytomeasurewiththeunaidedeye(thoughbinocularshelp). Indeed, thiswasthewholepointofCitizenSky; itbringsastronomyandastronomicalresearchtoanyone,ofanyage,anywhere. Asothershavepointedout,eacheclipseofeAurigaebringsanewgenerationofastronomers,andanewgenerationof technology.The1982–1984eclipsecoincidedwiththeblossomingofamateurphotoelectricphotometry(PEP).The2009–2011eclipsewasobservedwithCCDandDSLRcameras,aswellasPEPandvisualtechniques. Itwasalsoobservedwithspectroscopy,atechniquewhichisincreasinglyavailabletoamateurs,andwithpolarimetry—afrontiertechniqueforsuitably-equippedadvancedamateurs.Veryfewprofessionalobservatoriesarecarryingout long-termspectroscopicandpolarimetricobservations, so this isanareainwhichamateurscouldtakeuptheslackinthefuture.Thiseclipsewasalsoobservedwithanopticalinterferometer—GeorgiaStateUniversity’sCHARAarray—so,forthefirsttime,wecan“see”thismysterioussystem. Finally, this eclipse campaign benefitted from modern information andcommunication technology, including email, the Internet, and social media.These made the transfer, display, and storage of information efficient andeffective.Theyalsohelpedtoconnecttheinternationalnetworkofamateurandprofessionalobserversasneverbefore. Youwillnoticethattheauthorsofthepapersinthisissuecomefrommanycountries.Theobservationswhichamateursandprofessionalshavecontributedduring this eclipse campaign come from even more countries, so everycontributorispartofaninternationalcommunityofvariablestarobservers. Furthermore,thearchivaldataoneAurigaestretchbackforover160years.Thedata in theAAVSOInternationalDatabasecover the last seveneclipses(1847–1849,1874–1876,1901–1903,1928–1930,1955–1957,1982–1984,and2009–2011),includingobservationsbytheeminentFriedrichArgelanderofthefirstofthese.ThevariabilityofthestarwasfirstsuspectedbyJohannFritchin1821,duringthe1820–1822eclipse.The1847–1849eclipsewasobservedsystematically byArgelander and others. Hans Ludendorff (1904) suggestedthatthestarwasaneclipsingvariable.By1937,ithadengagedthemindsof

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some of the foremost astronomers of the time: Gerard Kuiper, Otto Struve,andBengtStrömgren(1937)statedthat“thephotometricandthespectroscopicdataoneAurseemtoleadtocontradictionsunparalleledinthestudyofothereclipsing systems”. By the 1955–1957 eclipse, the situation was even morecritical, as stellar astrophysics had matured greatly. Various models wereproposed,includingthepossibility(sinceruledout)thatthesystemcontainedablackhole.Today’sobserversarethusconnected,acrosstime,withyesterday’sobservers and interpreters. The AAVSO centennial, the centennial history(WilliamsandSaladyga2011),andthehistoricalpapersinthecentennialissueofJAAVSO(volume40,number1)weretimelyvehiclesforhelpingtomakethesehistoricalconnections. CitizenSky,andthisspecialissue,wouldnothavebeenpossiblewithoutthesupportofmanyorganizationsandpeople:theNationalScienceFoundationforgrantsupport(DRL-0840188);theAAVSOanditsstaffwhoprovidedin-kindsupport; theCitizenSky team:AaronPrice,RebeccaTurner,RobertE.Stencel,BrianKloppenborg,andArneA.Henden;partnerorganizationsandindividualswhocontributedtopartsoftheprojectsuchastheworkshopsandtutorials;theauthorsofthepapersinthisissue;andalltheobserversandothervolunteerswhocontributedtothediversescientificandeducationalaspectsoftheproject.Special thanks,asalways, to the staffof thisJournal:AssociateEditorElizabethWaagen,AssistantEditorMatthewTempleton,andProductionEditorMichaelSaladyga.Wehopethatyouenjoythisissue!

References

Kuiper,G.,Struve,O.,andStrömgren,B.1937,Astrophys. J.,86,570.Ludendorff,H.1904,Astron. Nachr.,164,81.Templeton,M.2008,http://www.aavso.org/vsotsepsaurWilliams,T.R.,andSaladyga,M.2011,Advancing Variable Star Astronomy:

The Centennial History of the American Association of Variable Star Observers,CambridgeUniv.Press,Cambridge.

JAAVSO Volume 40, 2012612

JAAVSO Volume 40, 2012 613

ε Aurigae Papers

Price etal., JAAVSO Volume 40, 2012614

The Origins and Future of the Citizen Sky Project

Aaron PriceRebecca TurnerAAVSO Headquarters, 49 Bay State Road, Cambridge, MA 02138; address email correspondence to R. Turner, [email protected]

Robert E. StencelBrian K. KloppenborgUniversity of Denver, Department of Physics and Astronomy, 2112 E. Wesley Avenue, Denver, CO 80208; [email protected]; [email protected]

Arne A. HendenAAVSO Headquarters, 49 Bay State Road, Cambridge, MA 02138; [email protected]

Received June 12, 2012

CitizenSkyaroseasaproductofthe2009InternationalYearofAstronomy(IYA)project.AaronPricewasappointedtotheU.S.IYAProgramCommitteewhenitwasfirstconstitutedin2006.Afteraboutayearofplanning,thecommitteeestablishedaWorkingGroupforResearchExperiencesforStudents,Teachers,andCitizenScientistswithAaronas thechair.Thegoalwas touse the IYAinitiativetopromotecitizenscienceprojectstothegeneralpublic.ThegroupmetforthefirsttimeattheAstronomicalSocietyofthePacificmeetinginChicago—2007.At the meeting they decided to focus their efforts around one projectinsteadofpromotingaslateofprojects.Manyspecific ideaswerediscussedduringamorningmeeting,butnothingcaughttheexcitementoftheentiregroup. Intheafternoon,AaronhadahallwaydiscussionwithRickFienberg,theneditor-in-chief of Sky & Telescope magazine. Rick mentioned the upcomingeAurigaeeclipseasapossibletopic.Hehadpreviouslyco-presentedapaperonthetopicwithRobertStencel(“Dr.Bob”)atthe2006meetingoftheInternationalAstronomicalUnion.Itseemedlikeanidealproject.Andastheworkinggroupresearcheditmore,itbecamemoreandmoreenticing.eAurisbrightenoughtobeseenfromthecity,itseclipsehasanamplitudethatcanbedetectedwiththenakedeye,ithappensveryrarely,itisdifficultforprofessionalstomonitor(dueto limited large telescope time)and, aboveall, itwas still anenigma—evenafteroveracenturyofresearchandspeculation. U.S.IYAfundingwasaconstantissue.TheProgramCommitteeonlyhadenoughfundstosupportasmallstaffandafewprojects.TheWorkingGroupknewthatanyprojecttheycameupwithwouldbetargetedatanarrowaudienceandsowouldnotreceivethesamelevelofsupportfromtheProgramCommitteethat a more generalized topic—such as the Galileoscope—received. So theWorkingGroupcameupwithtwoplans.Onewasaimedatwhattheywould

Price etal., JAAVSO Volume 40, 2012 615

dowithzerofunding—whateachmemberofthegroupcouldcontributegratisand/orcandoaspartoftheirregularjob.FortheAAVSO,thismeantissuinganAlert Noticeonthetopic,makingcharts,andrunningaregularcampaign,butnotmuchmore.Theyalsocameupwithaprogramtoimplementiftheycouldraise substantial levelsof support.After these twoplanswere inplace, theylookedforfunding. The National Science Foundation (NSF) seemed like a natural fit.Theyfund citizen science, have a nice history with theAAVSO, and the workinggrouphadsomeexperiencewritingproposalsforthem.However,strongNSFproposalsarenoteasytoassemble.IttookalmostsixmonthstowritetheCitizenSkyproposal.Aaronwroteadraft,circulateditamongsttheWorkingGroup,andthentheyheldconferencecallstodiscussrevisions.Theprocesswentverysmoothly,buttookalotoftime. AAVSO Director Arne Henden was chosen as the project’s principalinvestigator(PI)becauseAarondidnotyethaveaPh.D.(hewasingraduateschoolat thetime).Allof theco-PIscontributedtotheproposal.InadditiontoAaron, they were Lucy Fortson, Jordan Raddick, and Bob Stencel. RyanWyatt also contributed to the proposal and was a member of the advisoryboard along with Chris DuPree, Suzanne Jacoby, Hee-Sun Lee, and DavidAnderson.TheproposalitselfwasoriginallycalledSTARS—ScienceThroughtheAstronomicalResearchofStars.ItwasafterfundingthatitwaschangedtoCitizenSky,anamefirstproposedbyRebeccaTurner. RobertStencelservedasscientificadvisor fromtheverybeginning.Theoriginal idea to involve web cams and DSLR cameras began with him. Heprovidedmuchneededscientificadviceandalsoawelcomesenseofhumorwhenthingsgottightanddeadlinesloomed.Healsorecruitedagraduatestudentofhis,BrianKloppenborg,intotheproject. By the time we submitted the proposal to the NSF’s Informal ScienceEducation (ISE) program, which funds their citizen science projects, thebudget had increased to about $796,000 for a three-year project. It was aninterdisciplinary project with funding for modeling software, workshops, ahigh-endplanetariumshow,journalpublication,ScienceOlympiadmaterials,andmuchmore.ThescientificgoaloftheprojectwastocollectdatatohelpresearchersuncoverwhatiscausingtheeAureclipse.Theeducationalgoalwastoinvolvethepublicinallaspectsofascientificproject.Insteadoffocusingsolelyondatacollection,theprojectaimedtotrainparticipantstoanalyzedata,pose their own research questions, and write up results for a peer-reviewedjournal.Thishadnotbeendonebeforeinalargescalecitizenscienceproject,and theAAVSO was in a unique position to do so thanks to our history ofhavinganengagedmembership.ThegoalwithCitizenSkywas toput it alltogetherinonepackageandmakeitaccessibletonoviceamateurastronomerswiththebeliefthatparticipantswillgetabetterunderstandingofthescientificmethodiftheyaremoreengagedwithitateverystepoftheway.

Price etal., JAAVSO Volume 40, 2012616

TheproposalwassubmittedinJune2008.InNovember2008wereceivedthewordthatithadbeenfavorablyreviewedbytheNSF.OverthenextfewmonthsweansweredquestionsandrespondedtosuggestionsfromtheNSFtostrengthentheproject.Inmid-April2009wefinallyreceivedofficialnotificationthattheprojectwouldbefullyfunded.However,wewerenewtotheNSFsothereweresubstantialadministrative tasks tocompletebefore fundingcouldbegin.Thisadditionaldelaycausedaproblembecause,asweallknow,theskywaitsfornoone.Theeclipsewaspredictedtobegininthelatterhalfoftheyearandweneededpre-eclipseobservations.Intheoriginalproposalweplannedtohavealmostayeartobuildtheproject,materials,andsoon,beforetheeclipsebegan.Nowwehadtodoayear’sworkinafewmonths. Rebecca Turner was assigned the position of Project Manager, meaningshe was responsible for overall implementation of the project. Dr. Bob wasthescientificadvisor.BrianKloppenborgwashiredasastaffmembertoassistRebecca.Thefirstauthorwasfundedtoconductanevaluationoftheproject,whicheventuallymorphedintohisdissertationatTuftsUniversity.TheMorrisonPlanetariumattheCaliforniaAcademyofSciences,actingunderRyanWyatt,was contracted to produce an eight-minute planetarium film for the project.TheAdlerPlanetariumandAstronomyMuseum,actingunderMarkSubbaRao,washiredtodevelopaninteractiveeclipsingbinarymodelingsoftware.JordanRaddickatJohnsHopkinswashiredtoconsultonwebsitedevelopment,whichwasmostlydonebyKateDavis,theAAVSOwebmasteratthetime. Thefirstyearof theprojectwasdedicated tobuilding infrastructureanddatacollection.ThewebsitewasofficiallylaunchedinJune2009.Itconsistedof simplified versions of WebObs, the light curve generator, and the QuickLookfile,tutorialsonobservingandreadinglightcurves,onlineforums,andablogmaintainedbythestaffandDr.Bob.ThefirstCitizenSkyworkshopwasheldinSeptember2009attheAdlerPlanetariuminChicago.Thefocusoftheworkshopwasondatacollection(visual,photoelectric,andspectra)andonthesciencebehindthesystem. Thesecondyearoftheprojectwasdedicatedtobuildingteamsandtrainingindataanalysis.Thenon-observingaspectofCitizenSkywasdesignedaroundtheconceptof teamsofparticipantsworkingtogether.Itwasinspiredbythesuccess of the chart and comparison star database teams that were active intheAAVSO in thepreviousdecade.Asecondworkshopwasheld inAugust2010attheCaliforniaAcademyofSciencesinSanFrancisco.Thefocusofthatworkshopwasondataanalysisandwritingscientificpapers. Thethirdyearoftheprojectwasdedicatedtoobservingtheendoftheeclipseandwritingpapersfor theJournal of the AAVSO (JAAVSO).Thiswasa lesspubliclyactiveperiodastheteamsworkedontheirpapers,mostofwhicharepublishedinthiseditionofJAAVSO, abouteAur,CitizenSky,andrelatedtopics. SowhatishappeningnextwithCitizenSky?Oneofthelessonswelearnedin thisproject is that teamscanindeeddogreatwork.Evidenceof that is in

Price etal., JAAVSO Volume 40, 2012 617

thisJAAVSO issue.However, some teamsdidnotachieve theirgoals.Therearemanyreasonsforthis,butinourviewtherewasoneoveralllessontolearn:project staff cannot appoint leaders of teams; theyhave togroworganicallyfromamongtheparticipants.Themostsuccessfulteamsweremostlytheonesthathadself-nominatedleaders.Theteamswhichhadstaff-invitedleaderswerelesssuccessful,withafewnotableexceptions. AttheendofthethirdyearoftheCitizenSkyProjecttheAAVSOreceivedasupplementalNSFgranttofundathirdworkshop.ThisworkshopwillfocusongeneratingamanualforDSLRPhotometry.Applicationswillbeacceptedinlate2012andearly2013.ItwilltakeplaceMarch22–24,2013,atAAVSOHeadquarters in Cambridge, Massachusetts. The program will comprise amixof1)talksbyexperiencedDSLRphotometristsand2)breakoutsessionsduringwhichsmallgroupsofparticipants(eachwithadesignatedleader)willdeveloppreassignedsectionsofthemanual.Thesegroupswillbedeterminedwellinadvanceandwillbebasedonparticipantinterest,experience,andskills.NopriorDSLRexperienceisrequired,but therewillbesomepre-workshopreadingandpreparationrequired.Theworkshopwillproduceaneasytouse,introductory manual that will help the AAVSO support observers who areinterestedingivingDSLRphotometryatry. WiththeconclusionoftheeAureclipseandnewsoftheDSLRworkshop,theAAVSOhasgivenCitizenSkyanewmission:tobethenewhomeoftheAAVSO’sbrightvariablestaractivities. Initially, theCitizenSkyareaof theAAVSOwebsitewillhosttheAAVSOBinocularObservingProgramandtheDSLR Photometry Program.Additional bright object programs/projects willbe added to the Citizen Sky pages as they develop. Important Citizen SkymaterialswillbemovedfromitsexistingwebsitetotheCitizenSkysectionoftheAAVSOwebsite.TheoriginalCitizenSkywebsitewillbefrozenin2013butwillstayonlineasanarchive. Asforstaff,theyhavealsobuiltonwhattheyhavelearnedaspartofthisproject.Dr.BrianKloppenborg,whoreceivedhisPh.D.atUniv.ofDenverinspring2012,isnowavisitingscientistattheMaxPlanckInstituteforRadioAstronomy in Bonn, Germany, working on interferometry. He continues toinvolveamateurastronomersinhisresearch.Dr.AaronPriceisnowManagerofResearchandEvaluationattheMuseumofScienceandIndustryinChicago,whereheisapplyingthesocialscienceresearchskillshelearnedthroughhisdissertationonCitizenSky’simpactonthescientificbeliefsofitsparticipants.Rebecca Turner has been promoted to Operations Director at the AAVSO,whereshe isapplyingmanyof theprojectandpersonnelmanagement skillsshe learnedasProjectManagerof theCitizenSkyproject.Dr.ArneHendencontinues asDirectorof theAAVSO, andDr.RobertStencel continues as aprofessorattheUniversityofDenver,andisnowplanningobservationsforthenexteclipseofeAurin2036!

Stencel, JAAVSO Volume 40, 2012618

e Aurigae—an Overview of the 2009–2011 Eclipse Campaign Results

Robert E. StencelUniversity of Denver, Department of Physics and Astronomy, 2112 E. Wesley Avenue, Denver, CO 80208;[email protected]

Received March 19, 2012; revised May 30, 2012; accepted June 19, 2012

Abstract Evidenceisprovidedfromthearrayofobservationsamassedduringthe2009–2011eclipse,thatdefinestheenigmaticbinaryeAurigaeascomprisedof an unstable F0-1 Iab star in orbit around a comparable mass upper mainsequencestar(orstars)enshroudedinadiskresultingfromFstarmassloss.Inthispicture,theFstarmaybeundergoingrapidevolutionarychanges,andtherecent67-dayprimaryquasi-periodmaymakeitsuitableforasteroseismicstudies.Thehiddenstar(s)mayhavegainedmassfromtheFstar,andthediskitselfprovidesopportunitiesforstudyofaccretion,dustevolution,anddynamics.

1. Introduction

Duringthe20thcentury,thebrightstareAurigaeconfoundedastronomersbecause the visible member of this single-lined spectroscopic binary starappearedtobeamassive,F-typesupergiantstar,withanequally-massivebutinvisible companion (Guinan and deWarf 2002). Unimpeachable evidencefor the eclipsing object, a disk in transit, was obtained with interferometricimagingduringthe2009–2010eclipse(Kloppenborget al.2010),buildingontheinfrareddetectionofsamebyBackmanet al.(1984).Hoardet al.(2010),and previous authors, argued that the F star is in a volatile, reduced mass,post-AsymptoticGiantBranch(AGB)evoutionaryphase,withthecompanionbeingadisk-enshroudedB-typemainsequencestar—possiblynowthemoremassiveobjectinthesystem.Resolutionofthemassesandevolutionarystateofstarsinthissystemisaprimarymotivatorfortherecenteclipsecampaign,resultsofwhicharesummarizedinthispaper.ThisarticleispartofagroupofarticlescollectedintheJournal of the AAVSO,intendedtodocumentresultsofaninternationalefforttocollecthighqualityobservationsoftheeAursystemduring its 2009–2011 eclipse. Those reports provide details for each facet,butherewesummarizesomeoftheimportantfindings,inrelationtofindingsrecognizedasaresultofthestudiesofpreviouseclipses.

2. Results

AsdiscussedbyJeffHopkins(2012),photometricV-bandtimingsof thelatesteclipseareasfollows:

Stencel, JAAVSO Volume 40, 2012 619

Firstcontact: RJD55070 2009August16

“Second”contact: RJD55250 2010February22

Mid-eclipse: RJD55400 2010July22

“Third”contact: RJD55620 2011February27

Fourthcontact: RJD55800 2011August26

whereRJD=JD–2,400,000andtheuncertainty in timings isat leastone totwoweeks.Thenotionofcontacttimeshistoricallyreferstotangentcrossingsbetweenobjectsthatappearcircularinprojection,butwithaellipsoidaldiskshapeinvolved,thenormalmeaningsofsecondandthirdcontactsarechanged.Also,thesetimingsarecomplicatedbypersistent~0.1magnitudelightvariationsonaquasi-periodof67days(Kim2008).Spectroscopicevidencesuggeststhatdiskmaterialencroachedonthelineofsightmonthspriortophotometricfirstcontact(forexample,inKI7699A—seeLeadbeateret al.,thisissue),orevenyearsprior(Ha,seeChadimaet al.2011).SpectroscopicfourthcontactwasrecentlyannouncedbyobserverThierryGarrell,whoreportedexcessblue-shiftedHaandNaD-lineabsorptiondisappearedcircaRJD55950(2012January25). Theeclipsingobject isa large,550Kflattenedstructure,basedonrecentinfrared photometry and imaging. Although speculated to be a “swarm ofmeteors”byHansLudendorffearlyinthe20thcentury,thefirstphotometricevidencefortheeclipsingobjectwasprovidedbyMitchell(1964)withnine-colorphotometry,whoclaimeda500Kexcess,withaprojectedlinearsizeof50AU!Later,Backmanet al. (1984)observedeAurenteringeclipseandconfirmedthe result, reporting a 500K blackbody, with an apparent size of 8×10–16

ster-radians.At thereferencedistanceof650pc, this translates toanareaof14AUsquared,orequivalenttoarectangularshape1AUtalland14AUlong. The eclipsing object is disk shaped as seen in the near-IR. Thanks toremarkableprogressininterferometricimagingoverthepastdecade,itwaspossible in autumn 2009, during ingress, to detect the shadow of the diskcrossing the faceof theF star (Figure1),using theMIRCbeamcombinerat the Center for HighAngular ResolutionAstronomy (CHARA)Array oftelescopesatopMt.Wilson,California(Kloppenborget al.2010).Moreaboutthisbelow. Theneutralpotassiumlineat7699Åreappearedandshowedvelocityshiftsthatassociateitwiththediskanditsrotation.OriginallyreportedbyLambertandSawyer(1986),extensivemonitoringbyRobinLeadbeater(reportedinthisissue) showed a repeat of the phenomenon, demonstrating disk rotation andshowingstepwisechangesintheaddedequivalentwidthoftheline,suggestiveof disk substructure (Leadbeater and Stencel 2010). Subsequent study ofspectrarevealsanumberoflineswiththisbehavior(seeLeadbeateret al.2012;Schanneet al.2012;GriffinandStencel2012).


TheonlymoleculedetectedineAur,sofar,istransientcarbonmonoxide.ThiswasoriginallyreportedbyHinkleandSimon(1987),andshownbyStencelet al.(2011)toreappearagainaftermid-eclipse,usingbothmoderateresolutionIRTF+SpeXandhighdispersionGeminiNorthNear-IRSpectrometer(GNIRS)spectra. The data do not clearly confirm the low isotopic 12C/13C ratio ~10(comparedtothesolarvalue,89).TheoverlapofaPfundserieslineofhydrogenatop the 13CO bandhead demands post-eclipse observations where the COcontributionisremoved,allowingdisentanglementoftherelativecontribution.SeeFigures2aand2b.Alessextreme12C/13CratioreducestheevidencefortheFstarbeingalowermass,post-AGBstar. For the first time, transient HeI 10830Å absorption was detected, andit strengthened around mid-eclipse (Stencel et al. 2011), using NASA’sIRTF+SpeXinstrument;seeFigure3.Thislinearisesfroma19.8eVlevelandsuggestsahightemperaturecentralregioninthedisk.ThisisconsistentwithaccretionontoaB0-B5centralstar(Pequetteet al.2011). InfraredmonitoringconfirmedthepredictionbyTakeuti(1986)thatthesideofthediskfacingtheFstarisheatedto1100K(Hoardet al.2012),incontrasttothe550KsidefacingawayfromtheFstar.Amongtheimplicationsofthisarethatthebinaryseparationmightbeevaluated,independentoftheuncertaindistance,andthisdegreeofheatingisrelatedtothematerialpropertiesofthedustinthedisk. Aseriesofthreein-eclipseobservationsofthethefar-ultravioletspectrumofeAurwereobtainedwiththeCosmicOriginsSpectrograph(COS)onHubbleSpaceTelescope (Howell et al. 2011), and it was found that the continuumoutputissomewhateclipsed.Thefar-UVemissionlinesshowevidenceforaPCygni-likeoutflow(Figure4).Bothfactspoint tosurfaceactivityof theFstar,althoughcontributionsfromthediskcentralregionscannotberuledout. Attemptstoobservesolidstatespectralfeatures(ices,PAHs,or10-micronsilicates)failedtodetectany.InstrumentsinvolvedincludedSpeXandBASSatNASA’sIRTF,plusMIRACatMountHopkins(seeStencelet al.2011).Thebroadbandinfraredexcess,combinedwithlackofspectralfeatures,arguesthatthedustiscomprisedoflargeparticles(greaterthan~1micronsize).Kopal(1954)concluded similarlywhenstudying the similarityofeclipsedepthatmanyopticalwavelengths—theeclipse is“gray”due to largeparticlesizes,muchgreater than thewavelengths involved.Asnotedabove,eclipsedepthdeparturefromgrayness isseenatwavelengths longer thanseveralmicronsandintheultraviolet,andthesemayprovideusefulconstraintsonparticlesizeandtype. Photometric monitoring shows persistence of ~0.1 magnitude variationswithaquasi-periodof~67days(Kim2008),bothinandoutofeclipse(Figure5,andseeHopkins(2012)).ThesehavebeenassociatedwithFstaroscillationsandperhapswindevents(seeGriffinandStencel2012).


3. System parameters

Among the generally agreed system parameters are the eclipse period,9890±2days,and themassfunction in thissingle linespectroscopicbinary,f(M) =2.51±0.12 (Stefaniket al. 2010).System inclination seems securelyestablishedatverycloseto90degrees,basedoninterferometricimagesshowingthediskeclipsingtheprimarystar(Kloppenborg2010).Giventheseparameters,possiblesolutionsforthemassratio(q)includethe“highmass”case,q~1.1(sumofmasses,M+m~25M

Ä,andsemi-majoraxis,a~25AU)andthe“low

mass”case,q~0.5(M+m~9MÄ

,a~18AU),whereMistheFstarmass,andmreferstothemassofthesecondaryobject–assumedtobeastarinsidethedisk,andwhereaisthesemi-majoraxisoftheorbit.Astrometricsolutionsforbothextremeshavebeenpublished(Strand1959;vandeKamp1978).Workisunderwaytoincludeinterferometricresultsasanewconstraintoncombinedastrometricandphotometricsolutions(Kloppenborg2012),whichfavors thehighermasssolution. What constraints do we have on the mass (M) of the primary star?Classically, the spectral type of the primary star has been classified as anF0Iastar(7500K).Yellowsupergiantstarshavecatalogedmassesof12M

Ä

andabsolutemagnitude,MV=–6.6 (see, for example,StraizysandKuriliene1981). The historic q=1 solution for this single lined spectroscopic binaryimmediately called into question how a high mass companion could remaininvisibleoutsideoftheeclipsesitcauses(StruveandElvey1930).Usingtheapparentmagnitude,V=3.05andthereddening,AV=0.3,theimplieddistanceis740pc(about20%larger thanthatusedbyKloppenborg(2010)basedonthefirstHipparcosparallax).Fromthis,theimpliedluminosityis3.7×104L

Ä,

andtheimpliedradiusis115RÄ

—largerthanmostCepheids!At740pc,theangular diameterwould be 1.5 milli-arcsec (hereafter, mas), at least 0.5massmallerthanrecentinterferometricdeterminations(2.27mas,K-band,Stencelet al.2008).This requires thestar toeitherhaveunusual limbdarkening,orperhapsnotbeasdistantas740pc.Formally,a2.1masV-banduniformdiskdiameterindicatesadistanceof650pc. AninterestingconstraintonbinaryseparationcanbededucedfromrecentthermalIRdata,whichshowsthattheportionofthedisknearesttheFstarrisesto~1100K(Stencelet al.2011;Hoardet al.2012).Thisequilibriumtemperaturefordustparticles,withlowalbedo(0.3tozero),impliesaseparationfromthe7500KF0starof9to12AU.Foradiskradiusof4to5AU(seeKloppenborg2010),theimpliedbinaryseparationis13to17AU,whichismoreconsistentwiththeq=0.5solution.Thesumofmassesinthiscaserangesfrom3to7M

Ä.

However,adistanceof1kpcdistance,forexample,requiresawiderseparation(25AU)toyieldthesamedisktemperature,inaq=1binarywherethesumofmasseswouldbe25M

Ä.


In terms of resolving the ambiguity in distance and masses, twodevelopmentsdeservemention.DissertationworkbyBrianKloppenborg,attheUniversityofDenverat the timeof thiswriting,combinedastrometric,spectroscopic, and interferometric constraints on the orbit absolutedimensions. This resulted in a solution that places the system at 737±67pc, with a separation of 25AU and masses of M=13 and m=11M

Ä.The

interferometricallyconstraineddiskdiameterof7.31±0.66AUreferstotheoptically thickest portions and hence a minimum disk size, relative to thelargersizesimpliedbyspectroscopicconstraints. Whatotherconstraintsarepossibleonthemass(m)ofthesecondarystar?Diskrotationcurvesmaybeobtainedfromtheopticallythinneutralpotassiumlinesat7699Å(LambertandSawyer1986;Leadbeateret al.2012),seenonlyduringeclipsephases,andarguablyarisingfromextremeouterportionsofthedisk.Theirmeasureddiskrotationspeedis~35±–5km/sec.Rotationcurvesfromopticallythickermetalliclines(forexample,TiII4028Å)indicatethediskrotationspeedis42±–2km/sec(Saitoet al.1987).Then,withadiskradiusvalue,wecandetermineaKeplerianrotationperiodatthesespeeds.InterferometricimageswerefittedbyKloppenborg(2010)witha3.8AUellipticalsemi-majoraxis, assuming a 625pc distance. Said rotation speeds (35,42km/sec) haveimplied circumferential rotation rates of 3.25 and 2.70 years, respectively,implying a central mass of 5.2 to 7.5 M

Ä. Saito et al. (1987), using eclipse

timing arguments, deduced that m < 5.3 MÄ

, whereas Lambert and Sawyer(1986)deducedm=3to6M

Ä fromtheirneutralpotassiumlinevelocityas

ameasureofdisk rotation.These resultsstronglysuggest thesecondarystarmass,m,iscloseto4to6M

Ä,comparabletothatofamainsequence,B-type

star.However,withalargerdistance(737pc)andusinganopticallythindiskradius(10AU),theseorbitalspeedsareconsistentwithalargersecondarymass(m=11M

Ä).

Another constraint on the mass of the secondary can be inferred fromobserved disk dust and gas scale heights. As shown by VEGA+CHARAobservations (Mourardet al.2012), theeclipse inHa is total incomparisonto the partial eclipse seen in the near-IR with the Michigan InfraRed beamCombiner(MIRC)atCHARA—thatis,thehydrogengasextendsatleastafullFstardiameteraboveandbelowthediskplane.Forstrictlythermaldispersionofmaterial,thescaleheight(H)todiskradius(RD)ratioequalsthesoundspeed-to-orbitalvelocityratio,whichis:

[H/RD] = [(γkT / m)/(Gm/RD)]1/2 (1)

(seeLissaueret al. 1996), where γ is the ratio of specific heats (5/3 for ideal gases),mistheatomicmass,andmisthecentralstarmass.TablesandFiguresinLissaueret al.illustratethattheobservedthicknessisseveraltimesthescaleheight.TheobservedratiooftheminimumVEGA-observedthicknessofgas


disk(2.1milli-arcsec,mas)relativetotheestimatedopticallythickdiskradius(8.92mas–Kloppenborg2012),is0.24,suggestingascaleheighttodiskradiusratioof0.12to0.08.FortheHipparcosreferencedistanceof650pc,theimpliedopticallythickdiskradiusis5.8AU.Giventherangeofdisktemperatures,550to1100K,thethermalspeedofhydrogenatomsrangesfrom2.8to3.9km/sec,andwededucethequantity(Gm/R)1/2tobelessthanorequalto35km/sec,orimplyingagainthatthesecondarystarmass,m,islessthanorequalto10.7M

Ä.

Forthelargerdistanceestimate,1kpc,theimplieddiskradiusbecomes8.9AUandthedisktemperaturesresultinamaximummassof16.5M

Ä.Intheabsence

ofdynamicalstirring,thesemassesareanupperlimit,asthedisk’shydrogenatmosphere could be thicker. Higher gas temperatures and/or a thicker diskscaleheightbothpoint to a lower secondarymass. If theoptically thindiskradiusislargerthanimpliedbythephotometriceclipseduration,theresultantmasscouldbelarger. Arethereanyadditionaldistance-independentdiscriminators?OnemightbetheEddingtonlimitonluminosity,whichisclassicallycomputedtobe:

LEdd/LÄ=3.8×104M/M

Ä. (2)

Forthetwosolutionsoffered,m=3to4andm=15to25MÄ

,therespectiveEddingtonluminositiesare1.1–1.5×105L

Äversus5-9.5×105L

Ä.Bothranges

exceed the upper estimates for L/LÄ

. Other distance-independent means ofestablishingbinarystarparametersareneeded.

3.1.Natureofthedisk Kloppenborget al.(2010)estimatedthatthedisk-fittedsemi-majoraxisis6.10mas,meaningthefullmajoraxisis12.2mas,or~5.8timesFstardiameter(2.1mas).Giventhereported0.62masE-Wmotionpermonthduringingress(plusaN-Scomponent0.34mas/month,foranetmotionof0.72mas/month),anda2.1masuniformdiskdiameterstar,itshouldtake~2.9monthsforagivenpointinthedisktomoveacrosstheFstardisk,assuminguniformmotion,and~18monthstohavetheentirediskmovepast,whichisclosetotheobservedfirsttothirdcontacteclipseduration.Theellipsemodeldevisedduringingresswas poorly constrained, dictated mainly by the expected length of eclipse.Afterwards,weobtainedthecompletelightcurve(Figure5)andthefirst tofourthcontact lengthindaysisoforderRJD5800–5060=740days,or~24months,and largerstill inspectroscopic terms,suggesting thedisk is largerthanoriginallyestimatedand/or therelativevelocitiesarevarying(slowing,post-periastron). Evidenceexiststhatthediskisstructuredandasymmetric.Therehasbeenoutstanding spectroscopic monitoring of Ha by Mauclaire et al. (2012) andofKI7699ÅbyLeadbeateret al.(2012)andbluespectroscopicfeaturesbyGriffinandStencel(2012),reportedinthisissueandelsewhere,indicatingan


extended,asymmetricspectroscopicsignatureofthedisk.TheHaequivalentwidthchangesversustimesuggestacompactringmaycontributetolatephasesofingress(RJD55150–55250),whilethediskmainbodyisseenduringtotality(withapossiblemid-eclipsedeclinecircaRJD55450,perhapsduetoionizationrelatedtotheappearanceofHeI10830Å(Stencelet al.2011)).Amorediffusefollowingringassociateswithegress,butlastingpastnominalfourthcontact(RJD55800)withexcessHaabsorptionstillpresentinearly2012,agood150dayspastfourthcontact.Similarly,theneutralpotassiummonitoringhasbeeninterpretedtoshowstepwisechangesinequivalentwidthrelatedtointernalringstructure(LeadbeaterandStencel2010).ThesewerelabeledasringsAthroughF.RingsDandEmightcontributetothelateingressHabehavior,whileringsD-A associate with egress phenomena.As reported elsewhere, however, therelationshipbetweenthedustandgascomponentsisonlyjustbeingrevealedbyspectro-interferometryobtainedwiththeVEGAinstrumentattheCHARAArray(Mourardet al.2012). AdditionalsuggestionsofanionizingphotoninducedshockintheingresssideofthediskhasbeenmadebySaitoet al.(1987).Similarly,amattertransferstreamimpactingtheegresssideofthediskhadbeenadvancedbyStruveandcolleaguesearlyon,andsomethingtothiseffectwasseenagaininblueregionspectra reported by Griffin and Stencel (2012). Finally, the out-of-eclipsephotometricvariationsareconsistentwithsurfacephenomena-drivenmasslossepisodesfromtheFstarthatcontributetoastellarwind,asymmetricallyshapedtoward thecenterofmassand ionizedbyUV light scatteredaway from thesourceinternaltothedisk(Figure6).

3.2.Dustscattering Thecompositionof thedisk isof interestbecausedeterminingdust sizewould provide evidence for the age of the object and the degree to whichplanetessimal formationmay have occurred in the disk. Kopal (1954) notedthewavelength-independenceofeclipsedepthsandconcludedthatlargegrainsmustbepresentwithmulti-micronsizes,muchgreaterthanopticalwavelengths.However,observationstodatehavenotdetectedanytypicalspectroscopicbandsdue tosolids,suchas ice(3microns),PAHs,or10-micronsilicates(Stencelet al.2011).Anestimatefordiskmasscanbemade,basedonthefarIR/sub-mmfluxesreportedbyHoardet al.(2012):

M(dust)=Fnl2d2/(2kTdustkn) (3)

whereFn(250microns)=57mJy=3×10–22W/cm2/micron.Using650pcasthe distance, a dust temperature of 550K and a mass absorption coefficient,kn=3cm2/gm (Juraet al. 2001),wededuce a dustmassof 1.2×1031 gmor

nearly6Jupitermasses.Thisseemstoolargeifthegastodustratiois~100,because the disk mass would be dynamically significant in the system.


Disk volume (Kloppenborg et al. 2010) and deduced densities (Hinkle andSimon1987)argueforalowerdustmass,roughlyanEarth-mass.Dustopacitybasedonsub-mmdiskstudiessuggeststhatmassabsorptioncoefficientsarenotwelldetermined.FurtherworkisneededtobettercharacterizethematerialintheeAurigaedisk(seePearsonandStencel2012). Another avenue for exploring the disk content involves polarimetry.BroadbandpolarimetricstudieshavebeenreportedbyKempet al.(1986)andbyCole (2012).These showanoutofeclipsebaselinevalue inphotometricVbandof2.0percent,presumed tobe interstellar,butgrowingandvaryingduringeclipseto2.4percent.ThesubstructureofV-bandpolarizationduringeclipsedoesnotsimplycorrelatewithphotometricchanges.Kempet al.(1986)correctlydeducedthepositionangleoftheeclipsingdiskdecadespriortotheinterferometricimagingofit.Recently,linepolarizationmonitoringhasbecomepossible,greatlyincreasinginsightintodiskandstarphenomena,andgreatlycomplicatingtheanalysis(seeGeiseet al.2012). Onemore lineofevidence tobeexplored involvesadifferencebetweeneclipsebehavioramongredwavelengthlineslikeHaandKI7699Å,andbluewavelengthlineslikeFeI3920Åandothers.Theformershowequivalentwidthvariation due to the eclipse, but remain substantially enhanced around mid-eclipse,whilethebluerlineshaveequivalentwidthexcessthatnearlyvanishesatmid-eclipseandthenreturnsstronglyduringlateeclipse.Thisistosaythatthelinedepthchangesarelessintheblueregionscomparedtotheredregions,suggestiveofparticlesizesdominatedbythegreater-than-micronscale.

4. Archives

Table1listsobservationsthatthisauthorproposedandconducted,manyof which will appear in public data archives maintained by the institutionsinvolved.TheAAVSOprovidesacomprehensivephotometryarchive.Thereareanumberofspectroscopicdatasourcesthatmightnotbefullyreflectedinthisreport,butwellworththemention.InadditiontothecarefuldigitizationbyElizabethGriffinofMt.WilsonandDAOphotographicspectra(plusnewdigitalobservations),additionalmodernhighdispersiondigitalspectrawereobtainedregularly during eclipse by Hideyuki Izumiura at Okayama Observatory, byWilliamKetzebackandcollaboratorsatApachePointObservatory(seeBarentineet al. 2012),byNadineManset andcollaborators atCFHT (seeGeiseet al.2012),byJohnMartinattheUniversityofIllinois,Springfield,Observatory,byNancyMorrisonattheUniversityofToledoRitterObservatory,byUlisseMunari and collaborators atAsiago Observatory, by Klaus Strassmeier andcollaborators (Astronomical InstituteatPotsdam)STELLA telescopeat IAC(seeSchanneet al.2012),andseveralothers.Ideally,thesedataarchivescanbemaintainedbytheiroriginatorsandmadeavailabletointerestedresearchers.Thisauthorwouldbehappytotrytohelpcoordinateanalysisefforts.


5. Conclusions

ClarificationofthenatureoftheeclipsingobjectineAurwillstandasoneofthemajorachievementsofthiseclipsecycle.WhiletheeclipsehasbroughtattentiontothestudyofeAuranditsmysteries,wenowhaveenteredthelonginter-eclipseperiod,prior to the startof thenexteclipsecirca2036.Currentorbitalelements(Stefaniket al.2010)predictkeytimesthatshouldbeofinteresttoobservers:theFstarreachesmaximumblueshiftcircaautumn2017(anditreachedmaximumredshiftduringautumn2006).EclipseofthediskbytheFstar is anticipatedduring2020and this shouldbedetectable in the infrared,insofarastheobservationalcapabilityexiststhen.Thereismeritinphotometricmonitoringofout-of-eclipsebehavior,althoughthecharacteristicbehavior(67-dayquasi-periodplusovertonesandevolution)seemsestablished(forexample,Kim(2008)andKloppenborg(2012)).TheAAVSO’sphotometricdataarchive(www.aavso.org) provides an excellent resource. Nonetheless, with robotictelescopesanddedicatedpersons,theslowchangesinthissystemcanyetbefollowedduringthisnewestorbitalcycle.

6. Acknowledgements

Therearemany,manypeopletothankforhelpinthisoveralleffort,makingcoverageoftherecenteclipsethemostcompleteinhumanhistory.WithoutJeffHopkins’andLouBoyd’sdedicationtolongtermphotometry,wewouldhaveamuchsparserdataset.MythankstoHalMcAlisterforacceptingmyproposalstousetheCHARAArrayforinterferometricstudyoftheeclipse,andtoJohnMonnierforaccess to theMIRCinstrument thatmade the imagingpossible.ManyfacetsoftheworkpresentedherewerefacilitatedbyBrianKloppenborgandhisamazingcomputerskills.IamgratefultoAaronPrice,RebeccaTurner,andArne Henden atAAVSO for their efforts with the Citizen Sky observercampaignthatenrichedthedataarchiveswiththousandsofnewmeasures,allcarefully archived. Additional spectroscopic monitoring was contributed byRobinLeadbeater,ThierryGarrel,ChristianBuil,ElizabethGriffin,andmanyothers. Key collaborators on HST COS and Spitzer/IRAC data acquisitionincludedSteveHowellandDonaldHoard,withexcellentadvicereceivedfromCOSteammembersStephaneBeland,JimGreen,StevenPenton,andothers.Collaborators obtaining and reducing Gemini North GNIRS data were TomGeballeandRachelMason.Helpfulcommentsonthispaperfromananonymousrefereeareappreciated.MyparticipationwassupportedinpartbythebequestofWilliamHerschelWombleinsupportofAstronomyattheUniversityofDenver,forwhichIamextremelygrateful(astheprojectwouldnothavebeenpossibleotherwise),alongwithanNSF-RAPIDgrant,AST10-16678,totheUniversityofDenver,organizedbytheprescientprogramdirectorDonaldTerndrup,whodeservespublicthanksforrecognizingthesingularopportunityaffordedbyeAur.


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55084 2009Sep10 IRTF/SpeX 1–5-micronmed-resspectra55139 2009Nov2–4 CHARA+MIRC 1.6-microninterferometricimaging55140 2009Nov3 IRTF/SpeX 1–5-micronmed-resspectra55169 2009Dec2–4 CHARA+MIRC 1.6-microninterferometricimaging55197 2010Jan1 MMTO/MIRAC 10-micronphotometry/spectra55245 2010Feb18 CHARA+MIRC 1.6-microninterferometricimaging55250 2010Feb23 IRTF/SpeX 1–5-micronmed-resspectra55428 2010Aug19–21 CHARA+MIRC 1.6-microninterferometricimaging55432 2010Aug24 IRTF/SpeX 1–5-micronmed-resspectra55441 2010Sep1 HST/COS far-UVspectra55462 2010Sep22–23 CHARA+MIRC 1.6-microninterferometricimaging55467 2010Sep27 IRTF/SpeX 1–5-micronmed-resspectra55494 2010Oct24 MMTO/CLIO JHKLMphotometry55495 2010Oct25–26 CHARA+MIRC 1.6-microninterferometricimaging55499 2010Oct29 IRTF/SpeX 1–5-micronmed-resspectra55500 2010Oct29 Spitzer/IRAC 3.6and4.6-micronphotometry55513 2010Nov12 IRTF/SpeX 1–5-micronmed-resspectra55523 2010Nov22 Spitzer/IRAC 3.6and4.6-micronphotometry55537 2010Dec6 IRTF/SpeX 1–5-micronmed-resspectra55540 2010Dec9–10 CHARA+MIRC 1.6-microninterferometricimaging55540 2010Dec9 HST/COS 2ndfar-UVspectrum55553 2010Dec22 MMTO/MIRAC 10-micronphotometry/spectra55559 2010Dec28/9 GNIRSSV 2.3-micronhigh-resCOspectra55565 2011Jan04 GeminiN+GNIRS 2.3-micronhigh-resspectra55567 2011Jan06 IRTF/SpeX 1–5-micronmed-resspectra55582 2011Jan19 CHARA+MIRC4T 1.6-microninterferometricimaging55567 2011Mar3/4 IRTF+SpeX attempt,1–5-micronmed-resspectra55637 2011Mar17 HST+COS 1150–1800Åspectra(3rdepoch)55637 2011Mar17/18 CHARA+CLIMB 3Tinterferometry55649 2011Mar29 IRTF+SpeX JTR,1–5-micronmed-resspectra

Table1.SelectednewobservationsofeAurduringeclipse,2009–2011. RJD* Calendar Date Telescope Mode

Table continued on next page


55650 2011Mar30 GeminiN+GNIRS 2.3-micronhigh-resspectra55651 2011Apr1–5 CHARA+CLIMB 3Tinterferometry55663 2011Apr12 IRAC 3.5and4.5-micronphotometry55663 2011Apr12 GeminiN+GNIRS 2.3-micronhigh-resspectra55663 2011Apr12 Spitzer/IRAC 3.6and4.6-micronphotometry55678 2011Apr25 IRTF+MIRSI 10-micronphotometry55680 2011Apr29 Spitzer/IRAC 3.6and4.6-micronphotometry55814 2011Sep10 HSO–PACS 70,110,160-micronphotometry55824 2011Sep18 CHARA+MIRC6T 1.6-microninterferometricimaging55826 2011Sep21 HSO–SPIRE 250,350,500-micronphotometry55830 2011Sep24 CHARA+MIRC6T 1.6-microninterferometricimaging55830 2011Sep24 IRTF+SpeX 1–5-micronmed-resspectra55846 2011Oct10 CHARA+MIRC6T 1.6-microninterferometricimaging55869 2011Nov03 CHARA+MIRC6T 1.6-microninterferometricimaging55871 2011Nov05 MMT+MIRAC4 cloudedout55884 2011Nov17 Spitzer/IRAC 3.6and4.6-micronphotometry55894 2011Nov27 IRTF+SpeX 1–5-micronmed-resspectra55899 2011Dec02 Spitzer/IRAC 3.6and4.6-micronphotometry55913 2011Dec16 CHARA+MIRC cloudedout55915 2011Dec18 IRTF+SpeX 1–5-micronmed-resspectra*RJD = JD– 2400000.

Table1.SelectednewobservationsofeAurduringeclipse,2009–2011,cont. RJD1 Calendar Date Telescope2 Mode

Figure1.Historicfirst:the1.6-micronwavelengthimageofeAur2009November2asinitiallyprocessedbyJohnMonnier,basedonfourtelescopebeamcombinationdataacquiredbyMIRCattheCHARAArray,andshowingtheshadowofthediskcrossingthefaceofeAur.Thescalesareinmilli-arcsecondunits.Image courtesy of John Monnier, Univ. Michigan.


Figure2a.AportionoftheGeminiNorthGNIRSspectrumofeAurspanningthe12CO(2-0)bandheadat4360cm-1region(2.293microns)showingspectrallinesof12CO(2-0up)and12CO(2-0down), illustratingtheGNIRSresolutioncapable of separating these contributions. The lines show a –25 km/secsystematicblueshift,characteristicofthediskatthisepoch.

Figure2b.AportionoftheGeminiNorthGNIRSspectrumofeAurspanningthe13CO(2-0)bandheadat4265cm-1region(2.344microns)showingspectrallinepositionsof13CO(2-0),12CO(2-0),12CO(3-1)linesandhydrogenPfundlines.RedshiftedPfundlineabsorptionmayaccountforsome,orall,ofthepreviouslyreported13CObandheadnear2.345microns.

Figure3.TimeseriesofIRTF+SpeXdatashowingmid-eclipseappearanceofHe10830Å.


Figure4a.HST/COSspectraofeAur.ThestrongUVMgIIdoubletat1240Å(1239.925, 1240.395) but lack of N V (1238.821, 1242.804). The line near1243.3couldbeNI.

Figure4b.CIIprofilesshowingclearPCygnioutflow,unaffectedbyeclipsephase.


Figure5.Vmagnituderecordofthe2009–2011eclipseofeAurasrecordedbyavarietyofobservers.SeeStencelet al.(2011)fordetails.

Figure 6. Schematic model of eAur that incorporates F star wind focusingand ionizationeffectsdue toscatteringofUVphotonsoriginating inside thedarkdisk.Thismodelaccountsformanyofthenewlyobservedspectroscopicand radial velocity details reported here and in related papers, and providespredictionsforadvancedhigh-resolutionimaginginthefuture.

Hopkins, JAAVSO Volume 40, 2012 633

The International e Aurigae Campaign 2009 Photometry Report

Jeffrey L. HopkinsHopkins Phoenix Observatory, 7812 West Clayton Drive, Phoenix, AZ 85033; [email protected]

Received February 23, 2012; revised April 25, 2012, and June 29, 2012; accepted July 3, 2012

Abstract An International Campaign and Web site were started in Mayof 2006 for the 2009–2011 eclipse of the mysterious star systemeAurigae.Photometric and spectroscopic observations of the eclipse were coordinatedandreported.Theeclipsestarted in thesummerof2009and lasteduntil thespringof2011.Duringthecampaigntwenty-fournewsletterswerepublishedon theweb site andmadeavailable free as .pdf files to read anddownload.Twenty-sixobserversfromfourteendifferentcountriessubmittedphotometricdata in theUBVRIbands.Over3,600high-qualityphotometricobservationsweresubmittedwithnearly2,000observationsinjusttheVband.ThispaperdiscussestheCampaignandreporttheresults.

1. Introduction

Priortotheeclipse,datafrompreviouseclipsesandfrombetweeneclipseswereconsolidated in the formofabook (seeHopkinsandStencel2008).Apaperwasgiven at theSociety forAstronomicalSciences2010Symposiumthatdiscussedtheingressofthelatesteclipse(Hopkinset al.2010).Mostofthephotometricdataforthe2009–2011eclipsewereobtainedintheVband.Thelargestphotometricchangeswereintheintheshorterwavelengths,however.TheUband,whichwasonlyobservedwiththePMT-basedsystems,providedthelargestchanges. Some people thought that during the late spring and early summer thestarsystemwentbehindtheSunandwasnotobservable.Thisisnottrue.ThedeclinationofthestarsystemishighabovetheplaneofthesolarsystemanditnevergoesbehindtheSun.Theproblemisthatatlowerlatitudesitgetsveryclose to thehorizonduring thedarkhoursand thus the lightpasses throughvery high air mass. Extinction becomes a very significant problem. Thoseobserversathigherlatitudescouldobservethesystematlowerairmasses,butasonegoesfarthernorththenumberofdarkhoursdecreasestothepointofthemidnightSun.Someof thehigher-latitudeobserversdidheroicworkduringthesepoorobserving times.Even then thedataaresomewhatconfusingandnoisy.Themid-eclipsebrighteningperiodwasatoneofthesepoortimes.Somedataindicatethebrighteningandsomeindicatenobrightening.Also,midway

Hopkins, JAAVSO Volume 40, 2012634

duringegresswasapoor timeandsomething interestinghappened then too.Thereseemstobeaknee in theegressphotometricplots.Perhapsmoreandbetterdataduringthesetimescanbeobtainedduringthenexteclipsein2036. A Campaign was formed during the 1982–1984 eclipse and thirteennewsletters published. The current Campaign’s web site has some of thesenewslettersavailableonline.Forthe2009–2011eclipsethereweretwenty-fournewsletters published by the Hopkins Phoenix Observatory.All of these areavailableas .pdfsontheCampaignwebsitealongwithagreatdealofotherpertinentdataoneAur.Inadditiontothe2009Campaign’swebsiteathttp://www.hposoft.com/Campaign09.html, a Campaign Yahoo forum was startedandcanbeaccessedat:http://tech.groups.yahoo.com/EpsilonAurigae/

2. Observations summary

AsofDecember26,2011,wehadnearly3,700totalobservationsreportedduring the eclipse, with the visual band having by far the most at nearly2,000observations.Twenty-sixobservers fromaround theworldcontributedobservationaldata.Table1isasummaryoftheobserverscontributions.

3. Data quality

eAurisbrightenoughtobevisuallyseeneasilyeveninmostlightpollutedareas.Onecanevennoticethedimmingoftheeclipsevisually.Whiletheuseofvisualobservationsforplottingchangesinthebrightnessofstarsworkswellwithsomestars,theeclipseofeAurwasnotagoodprojectforvisualwork.Tobeofvaluemagnitudesestimatesmustbeofaresolutionof0.05magnitudeor better. This is an order of magnitude less than what even experiencedvisualobserverscanproduceunderthebestofconditions.ForthisreasontheInternationalCampaigndidnotuseanyvisualmagnitudeestimates. Photometricdatasubmittedtothecampaignhadaveragestandarddeviationsforthreeormoredatapointsofmagnitude0.01.Manyobservationsapproachedastandarddeviationofmagnitude0.001.Thestandarddeviationisusedasanindicationofthequalityofthedatabyrepresentingadataspreadofthreeormore data points.The photometric plots do not have error bars because thestandard deviations, which would be used for the error bars, are too smallinrelation to theplotscale.Mostsubmitteddatahavebeentransformedandcorrectedfornightlyextinction.TheHopkinsPhoenixObservatory(HPO)usedahigh-precisionUBV1P21-basedphotoncountingsystem.AllHPOdataweredeadtimecorrected,transformationcoefficientsdeterminedforeachband,andnightlyextinctioncoefficientsdeterminedforeachband.DatareductionwasdoneusingtheHardieequations.MagnitudesweredeterminedforbothlAurandeAurandthendifferentialcalculationsdoneandnormalizedtothestandardvaluesforlAur’smagnitudes.Nightlysessionsconsistedofthreecomparison


starmeasurementsineachband,threeadjacentskymeasurementsineachband,followedbythesameroutinefortheprogramstar.Therewerethreesetsofthesemeasurementsmadewiththeprogramstarbracketedbythecomparisonstar.Thedatawerealltransformedandextinctioncorrected.Threemagnitudesweredeterminedforeachband,astandarddeviationcalculated,andthemagnitudeaverageforeachbandreportedtofourplaces. TherehasbeensomeconcernabouttheUandBmagnitudesfromtheHopkinsPhoenixObservatory.First,therearenostandardUandBmagnitudesforeAur.Thestarsystemvariessignificantlyandrandomlyout-of-eclipse.ThevariationisgreatestintheUandBbands.Ifoneweretosuggestout-of-eclipsemagnitudes then theaverageofseveralseasonsofout-of-eclipsemagnitudescouldbe specified,but awarningwouldbeneeded indicating that these areaverages.Fromdata takenout-of-eclipsebetweenMarch1986andFebruary2008,thefollowingaremaximum,minimum,andaveragemagnitudesfortheUBVbands:

Vavg=3.04 Vmin=3.16 Vmax=2.94 Bavg=3.61 Bmin=3.53 Bmax=3.69 Uavg=3.73 Umin=3.60 Umax=3.92

Oneofthegreatthingsaboutacampaignlikethisisthatonegetsachancetocomparetheirphotometricdatatakenatapproximatelythesametimeagainstothers.Photometriclightcurvesforthecampaignwereupdatedandpublishedonthewebaroundonceamonth.Observerscouldidentifytheirdataandseehowwelltheycomparedtoothers.Noisydataareobvious.Iftheobserverwasinterested, he or she could investigate the differences and improvements intechniqueanddatareduction.

4. Comparison star

ThereareavastnumberofobservationsofeAurcoveringmanydecadesthatuselAurasacomparisonstar.BecauseduringthistimelAurhasbeenfoundtobeverystableoverseveraldecades,nocheckstarisneeded.TheUBVmagnitudesarethoseusedintheprevioustwoeclipses.ThelongerwavelengthmagnitudeswereobtainedfromtheAAVSO. Thedatausedforthecomparisonstarare:

Comparisonstar: lAurOtheridentification: SAO40233,HR1729,HD34411Position: R.A.(2000)05h19m08.4s,Dec.(2000)+40°05'57"Magnitudes: U=5.46,B=5.34,V=4.71,Ij=3.88,Ic=4.00,Rj=4.19, Rc=4.30,J=3.62,H=3.33


5. Equipment

Therewerefourtypesofinstrumentationusedtoacquiredataforthe2009Campaign:DigitalSingleLensReflex(DSLR)cameras,CCDcameras,PinDiode photometers (SSP-3 and SSP-4), and photon counting photometers(PMT-based). The photon counting provided highest quality UBV datafollowedbytheSSP-3forBVdata.ObtainingCCDdatawasmoredifficultas thebrightnesscausedproblems.CCDprovidedBVRIdata.Thelastandnewest equipment for photometry were the DSLR cameras. The DSLRprovidedV-banddatabyusingthegreenchanneloftheRGBimages.WiththeexceptionofacoupleDSLRobserversthedatasubmittedwereverynoisy.However,DSLRcamerasofferanexcellentintroductiontophotometry.OnceanobserverisconfidentwithdoingphotometrywithaDSLR,anentrylevelmonochromeCCDcamerawithBVRIphotometric filterswouldbeagreatwaytostartdoingprofessionalphotometry.

6. Results

6.1.HopkinsPhoenixObservatorydata The Hopkins Phoenix Observatory data were taken with a high-precision UBV photon counting system.All data were transformed, deadtimecorrected,andnightlyextinctiondeterminedandcorrected.Detailsofthe photometric work at the Hopkins Phoenix Observatory is reported inHopkinset al.(2007). When out-of-eclipse the star system has presented tantalizing data(Figure 1).The light is not constant, but varies at a pseudo-periodic rate inall thephotometricbands.Theperiod isnot stable,andvariesunpredictablybetween50and70days.Inadditiontotheperiodvariationstheamplitudesvaryunpredictably.Periodanalysiswasdoneusingperansoperiodanalysissoftware(Vanmunster2007),butnoperiodcouldbedetermined.DetailsofthisworkarereportedinHopkinsandStencel(2007)andHopkinset al.(2008). While not photometry, in an attempt to shed light on the out-of-eclipsevariations high-resolution out-of-eclipse spectroscopy of the star system’sHa region was done at Hopkins Phoenix. The main Ha absorption line isbracketedbyemissionlines(horns)thatgoupanddown,sometimestogetherandsometimescompletelyindependently(seeFigure2).Theysometimesreacha large peak and at other times disappear completely. This is known as the“HydrogenAlphaHornDance.”Noconnectionwas foundbetween theout-of eclipse Ha spectroscopic variations and the out-of-eclipse photometricvariations.Theemissionhornsdidseemtodecreaseandevengoawayforawhile during the eclipse, however. Details of the spectroscopic observationsatHopkinsPhoenixObservatoryarereportedinHopkinsandStencel(2009a,2009b)andHopkins(2012).


6.2.Campaigndata HighdataproducersfortheeAurcampaignwereasfollows:

DSLR:DesLoughney,Edinburgh,Scotland—238V-bandobservations.CCD:GerardSamolyk,Greenfield,Wisconsin—721BVRcIcobservations.SSP:PaulJ.Beckmann,JimBeckmannObservatory,MendotaHeights, Minnesota—89BVRjIjobservations;Photoncounting:JeffHopkins,HopkinsPhoenixObservatory,Phoenix, Arizona—565UBVobservations.

Observation techniques varied among observers. Details of each observerare presented on the 2009 Campaign’s web site at http://www.hposoft.com/Campaign09.html.

6.3.Campaignlightcurves SeeFigures3through7.UBVRIJHphotometricdatafrom1982to2012arearchivedandavailableinmultipleformatsathttp://www.hposoft.com/Eaur09/Data/UBVRIJHData.html.

7. Analysis

Therehasbeensomeconcernexpressedbyarmchairphotometristsaboutthecontact times.Thefollowingmayhelpunderstandthecomplexityofthissystemandthemethodologyusedtodeterminethecontactpoints. TheeAurstarsystemisverydifferentfrommosteclipsingbinarysystems.Fortheanalysisofthecontactpointstheclassicalmethodwasused.Inadditiontothenon-classicaleclipsingbody,complicatingtheanalysisarethepseudo-periodicout-of-eclipse(OOE)variations(seeFigure8). Figure9showstheprocedurefordeterminingthecurrenteclipsecontactpoints.Theaverageingressandegressslopeswereusedtofindtheintersectionwiththeaveragetotalityandout-of-eclipsemagnitudes. An archive of UBVRIJH photometric data is available to the public at http://www.hposoft.com/EAur09/Photometry.html and http://www.hposoft.com/EAur09/Data/UBVRIJHData.html. A summary of the data is given in Table 2.

8. Predictions for the 2036–2038 eclipse

While I am unlikely to be around for the next eclipse in 2036 it is stillinterestingtoofferphotometricpredictionsaboutit.OnlytheV-bandcontactpointsareincluded.Thereisstillcontroversyaboutthesecondandthirdcontactpoints.Thesedateswerecalculatedbyadding9,898daystothefirstcontact,mid-eclipse,andfourthcontactofthe2009–2011contacttimes.


TheV-bandpredictionsare:

firstcontact:JD2464964±12days,September27,2036;mid-eclipse:JD2465283±9.5days,August12,2037;fourthcontact:JD2465601±7days,June26,2038.

9. Conclusion

EacheclipseofeAurseesanewbreedofequipmentandobservers.Whilemorewaslearnedfromthislatesteclipse,thestarsystemisnotgivingupitssecretseasily.Itseemstobetauntingus.Duringsomeofthemostinterestingtimes,thesystemwasextremelydifficulttoobserve.Theeclipsemaybeoverforanothertwenty-sevenyears,butthestarsystemstillpresentssomeinterestingchallenges. Monitoring and understanding the out-of-eclipse variationswillbeamajorobjective.This is followedby thestrangeHahorndance.Acontinuedfollowingofthestarsystemwithbothphotometricandspectroscopicobservationsissuggested.Thismayprovidesomeadditionalinsightsintothesemysteries.Oneofthenicethingsaboutobservingout-of-eclipseisthetimesofhighairmasscanusuallybeavoided.Observingcanbedoneduringfavorabletimes,suchasintheearlyfall,duringwinter,andinearlyspring.Asindicatedearlier, the most active regions for photometry are the shorter wavelengths.Uband is a especially important band in which to make observations. Thesystemalsooffers excellent spectroscopic learning for thehydrogenBalmerlinesaswellasthesodiumDlines.

10. Acknowledgements

I would like to thank all the observers who contributed data to theCampaign. Inparticular Iwant to thankDr.RobertStencel (“Dr.Bob”)andBrianKloppenborgfor theirhelp,encouragement,and thehonorofworkingwiththembothwiththeCampaignandespeciallywiththeobservingsessionsatCHARAonMountWilsoninCalifornia,andtheMMTonMountHopkinsinsouthernArizona.Thosearetreasuredexperiencesandmemories.

References

Hopkins, J. L. 2012, Small Telescope Astronomical Spectroscopy, HopkinsPhoenixObservatory,Phoenix,AZ.

Hopkins, J. L., Schanne, L., and Stencel R. E. 2008, in The Society for Astronomical Sciences 27th Annual Symposium on Telescope Science,SocietyforAstronomicalSciences,RanchoCucamonga,CA,67.

Hopkins,J.L.,andStencel,R.E.2007,inThe Society for Astronomical Sciences 26th Annual Symposium on Telescope Science,Society forAstronomicalSciences,RanchoCucamonga,CA,37.


Hopkins, J., and Stencel, R. E. 2008, Epsilon Aurigae: A Mysterious Star System,HopkinsPhoenixObservatory,Phoenix,AZ.

Hopkins,J.L.,andStencel,R.E.2009a,eAurigaeHydrogen-aEmissionLineVariations:TheHornDance,J. Amer. Assoc. Variable Star Obs.,37,213.

Hopkins,J.L.,andStencelR.E.2009b,inTheSociety for Astronomical Sciences 28th Annual Symposium on Telescope Science,Society forAstronomicalSciences,RanchoCucamonga,CA,157.

Hopkins,J.L.,et al.2010,inThe Society for Astronomical Sciences 29th Annual Symposium on Telescope Science, Society for Astronomical Sciences,RanchoCucamonga,CA,13.

Vanmunster,T.2007,peransoperiodanalysissoftware,http://www.peranso.com.

CH 143 — — — — — — 143 DSLR CO 3 — — — — — — 3 CCD CQJ 100 100 — — — 95 — 295 CCD DES 242 — — — — — — 238 DSLR EAO 68 — — — — — — 68 CCD EGO 81 — — — — — — 81 DSLR EUO 1 39 9 — 40 — — 89 PMT FJM 65 — — — — — — 65 SSP-3 GHO 165 — — — — 160 — 325 CCD GO 22 — — 20 — — — 42 CCD GS 179 178 — 183 — 181 — 721 CCD GVO 13 8 — — 13 — 13 47 SSP-3 HPO 147 209 209 — — — — 565 PMT JBO 16 41 — — 16 — 16 89 SSP-3 JESO 34 — — — — — — 34 CCD KO 111 — — — — — — 111 CCD LO 87 — — — — — — 87 SSP-3 MSO 3 3 — — — — — 6 CCD NKO 38 — — — — — — 38 DSLR NPO — — — — 18 — 18 36 SSP-3 RES 56 — — — — — — 56 DSLR RLO 29 — — — — — — 29 DSLR SGGO 67 17 — 59 — — — 143 CCD TP 86 — — — — — — 86 DSLR VO 193 — — — — — — 193 DSLR WWC 50 42 — — — — — 92 DSLR

Total 1999 637 218 262 87 436 47 3686

Table1.2009eAurcampaignphotometricobservercount.

Observer1 V B U Rc Rj Ic Ij Total Equipment2



Table1.2009eAurcampaignphotometricobservercount,cont.1 Observers (AAVSO observer initials are given in parentheses): CH (HEN), Colin Henshaw, Tabuk, Saudi ArabiaCO (OSC), Steve Orlando, Custer Observatory, East Northport, NYCQJ (CQJ), John Centala, Eastern IowaDES (LDS), Des Loughney, Edinburgh, Scotland, UKEAO (SIAK), Iakovos Marios Strikis, Elizabeth Observatory of Athens, Haldrf (Athens), GreeceEGO, Charles Hofferber, East Greenwood Observatory, East Grand Forks, MNEUO, Serdar Evren, Ege University Observatory, Izmir, TurkeyFJM (MFR), Frank J. Melillo, Holtsville, NYGHO (MXL), Richard Miles, Golden Hill Observatory, Dorset, EnglandGO (CLZ), Laurent Corp, Garden Observatory, Rodez, FranceGS (SAH), Gerard Samolyk, Greenfield, WIGVO (MBE), Brian E. McCandless, Grand View Observatory, Elkton, MDHPO (HPO), Jeff Hopkins, Hopkins Phoenix Observatory, Phoenix, AZJBO (BPJ), Paul J. Beckmann, Jim Beckmann Observatory, Mendota Heights, MN JESO, Dr. Mukund Kurtadikar, Jalna Education Society Observatory, Maharashtra, IndiaKO (LHG), Hans-Goran Lindberg, Kaerrbo Observatory, Skultuna, SwedenLO (GSN), Snaevarr Gudmundsson, Lindarberg Observatory, Hafnarfjordur, IcelandMSO, Arvind Paranjpye, MVS IUCAA Observatory, Ganeshkhind Pune, IndiaNKO, Nils Karlsen, Nils Karlsen Observatory, Umea, SwedenNPO, Gary Frey, North Pines Observatory, Mayer, AZRES (SVR), Dr. Robert E. Stencel, University of Denver, Denver, CORLO (HHU), Hubert Hautecler, Roosbeek Lake Observatory, Boutersem Brabant, BelgiumSGGO (CTIO), Tiziano Colombo, S. Giovanni Gatano al Observatory, Pisa, ItalyTP, Tom Pearson, Virginia Beach, VAVO (KTHA), Thomas Karlsson, Varberg Observatory, Varberg, SwedenWWC (CDK), Donald Collins, Warren Wilson College, Ashville, NC2 Equipment key: CCD, CCD Camera and telescope; DSLR, Digital Single Lens Reflex Camera, unguided; SSP-3, PIN Diode photometer with telescope; PMT, Photomultiplier Tube, photon counting with telescope.

U bandOOEMag. 3.725Mag. 3.73Mag.(1982–1984) D0.230Mag.1stContact RJD=55,062 ±21days RJD=55,0652ndContact RJD=55,193 ±21days RJD=55,237Ingress 131days ±26.5days 120days(1982–1984)Mid-Eclipse RJD=55,377 ±14daysTotality AverageMag. 4.525Mag. 4.57Mag.(1982–1984) AverageDepth 0.800Mag. Duration 438days ±10days 455days(1982–1984)3rdContact RJD=55,631 ±09days

Table2.2009eAurcampaigndatasummary. Parameter Observed Error Predicted1

RJD = JD–2400000 RJD = JD–2400000

Table continued on following pages



4thContact RJD=55,693 ±09daysEgress 62days ±37.5days 55days(1982–1984)Eclipse Duration 631days ±14days 630days(1982–1984) AverageDepth 0.800Mag. 0.84Mag. Period 9,882days ±21days 9,885days

B bandOOEMag. 3.605Mag. 3.61Mag.(1982–1984) D0.150Mag.1stContact RJD=55,089 ±12days RJD=55,0542ndContact RJD=55,202 ±12days RJD=55,214Ingress 113days ±12days 135days(1982–1984)Mid-Eclipse RJD=55,391 ±19.5daysTotality AverageMag. 4.325 4.32Mag.(1982–1984) AverageDepth 0.720Mag. Duration 432days ±09.5days 437days(1982–1984)3rdContact RJD=55,634 ±07days4thContact RJD=55,693 ±07daysEgress 59days ±07days 71days(1982–1984)Eclipse Duration 604days ±19.5days 643days(1982–1984) AverageDepth 0.720Mag. 0.71Mag. Period 9,919days ±12days 9,884days

V band2

OOEMag. 3.035Mag. 3.03Mag.(1982–1984) D0.130Mag.1stContact RJD=55,066 ±12days RJD=55,0562ndContact RJD=55,199 ±12days RJD=55,213Ingress 133days ±12days 142days(1982–1984)Mid-Eclipse RJD=55,384.5 ±09.5daysTotality AverageMag. 3.710Mag. 3.73Mag.(1982–1984) AverageDepth 0.675Mag. 0.70Mag.(1982–1984) Duration 430days ±09.5days 447days(1982–1984)3rdContact RJD=55,629 ±07days4thContact RJD=55,703 ±07daysEgress 74days ±07days 65days(1982–1984)Eclipse Duration 637days ±09.5days 654days(1982–1984)

Table2.2009eAurcampaigndatasummary,cont. Parameter Observed Error Predicted1

RJD = JD–2400000 RJD = JD–2400000



AverageDepth 0.675Mag. 0.70Mag. Period 9,898days ±12days 9,908days

Rc bandOOEMag. 2.745Mag. D0.630Mag.1stContact RJD=55,073 ±67days2ndContact RJD=55,217 ±67daysIngress 144days ±67daysMid-Eclipse RJD=55,333 ±45.5daysTotality AverageMag. 3.415Mag. AverageDepth 0.670Mag. Duration 406days ±17.5days3rdContact RJD=55,623 ±34days4thContact RJD=55,695 ±34daysEgress 72days ±34daysEclipse Duration 622days ±45.5days AverageDepth 0.670Mag. Period —

Ic bandOOEMag. 2.255Mag. D0.410Mag.1stContact RJD=55,054 ±42days2ndContact RJD=55,202 ±42daysIngress 148days ±42daysMid-Eclipse RJD=55,414 ±32.5daysTotality AverageMag. 2.985Mag. AverageDepth 0.720Mag. Duration 424days ±32.5days3rdContact RJD=55,626 ±23days4thContact RJD=55,707 ±23daysEgress 81days ±23daysEclipse Duration 625.3days ±37.5days AverageDepth 0.730Mag. Period —


RJD = JD–2400000 RJD = JD–2400000


J bandOOEMag. 1.840Mag. D0.160Mag.1stContact RJD=55,060 ±30days2ndContact RJD=55,210 ±30daysIngress 150days ±30daysMid-Eclipse RJD=55,391 ±18daysTotality AverageMag. 2.480Mag. AverageDepth 0.640Mag. Duration 404days ±18days3rdContact RJD=55,614 ±14days4thContact RJD=55,722 ±14daysEgress 108days ±14daysEclipse Duration 662days ±18days AverageDepth 0.640Mag. Period —

H bandOOEMag. 1.605Mag. D0.645Mag.1stContact RJD=55,057 ±15days2ndContact RJD=55,202 ±15daysIngress 145days ±15daysMid-Eclipse RJD=55,395 ±15.5daysTotality AverageMag. 2.050Mag. AverageDepth 0.645Mag. Duration 388days ±15.5days3rdContact RJD=55,590 ±14days4thContact RJD=55,733 ±14daysEgress 143days ±14daysEclipse Duration 676days ±09.5days AverageDepth 0.645Mag. Period —1 The predicted times were calculated by adding the previous eclipse times to the previous determined periods. 2 There were no predictions for the longer wavelengths in the V band.


RJD = JD–2400000 RJD = JD–2400000


Figure 3. e Aur lightcurve, September 1982–May 1984: top, V band;middle, B band; bottom,Uband.HopkinsPhoenixObservatorydata.

Figure 4. e Aur lightcurve,August2009–April2009:top,Vband;middle,B band; bottom, Uband. Hopkins PhoenixObservatorydata.

Figure2.eAurHaspectrum.

Figure1.eAurout-of-eclipselightcurves:top,Vmagnitude;middle,Bmagnitude;bottom,Umagnitude.


Figure5.eAurcampaignVdata.SeeTable1forkeytoobserveridentification.

Figure6.eAurcampaignUandBdata.SeeTable1forkeytoobserveridentification.

Figure7.eAurcampaignRandIdata.SeeTable1forkeytoobserveridentification.


Figure8.Classicalcontactpoints(top)andeAurnewcontactpoints(bottom).

Figure9.Contactpointdeterminationmethodology.

Kloppenborgetal., JAAVSO Volume 40, 2012 647

An Analysis of the Long-term Photometric Behavior of e Aurigae

Brian K. KloppenborgDepartment of Physics and Astronomy, University of Denver, 2112 East Wesley Avenue, Denver, CO 80208; [email protected]

Jeffrey L. HopkinsHopkins Phoenix Observatory, 7812 West Clayton Drive, Phoenix, AZ 85033; [email protected]

Robert E. StencelUniversity of Denver, Department of Physics and Astronomy, 2112 E. Wesley Avenue, Denver, CO 80208;[email protected]

Received June 1, 2012; revised October 4, 2012; accepted October 4, 2012

Abstract

Thelureofa50%reductioninlighthasbroughtamultitudeofobserversandresearcherstoeAureverytwenty-sevenyears,butfewhavepaidattentiontothesystemoutsideofeclipse.Asearlyasthelate1800s,itwasclearthatthesystemundergoessomeformofquasi-periodicvariationoutsideoftotality,butfewconsideredthiseffectintheirresearchuntilthemid-1950s.Inthisworkwefocusexclusivelyontheout-of-eclipse(OOE)variationsseeninthissystem.Wehavedigitizedtwenty-sevensourcesofhistoricphotometryfromeighty-onedifferentobservers.Twoofthesesourcesprovidetwenty-sevenyearsofinter-eclipseUBVphotometrywhichwehaveanalyzedusingmodernperiodfindingtechniques.WehavediscoveredtheF-starvariationsaremulti-periodicwithatleasttwoperiodsthatevolveintimeatDP ≈ –1.5 day/year. These periods are detectedwhentheymanifestasnear-sinusoidalvariationsat3,200-dayintervals.We discuss our work in an evolutionary context by comparing the behaviorfoundineAurwithbona-fidesupergiantandpost-AGBstarsofsimilarspectraltype.Baseduponourqualitativecomparison,wefindthephotometricbehaviorof the F-star in the eAur system is more indicative of supergiant behavior.Thereforethestarismorelikelytobea“traditionalsupergiant’’thanapost-AGBobject.Weencouragecontinuedphotometricmonitoringofthissystemtotestourpredictions.

1. Introduction

eAurigaeisa27.1-yearsinglelineeclipsingspectroscopicbinarythathaslong been wrapped in an enigma. Ever since a dimming of the system was

Kloppenborgetal., JAAVSO Volume 40, 2012648

discoveredbyFritsch(1824),anditsperiodicityestablished(Ludendorff1903),astronomershavespeculatedaboutthecauseofthisvariation.Baseduponradialvelocitymeasurements,eAurwasclassifiedasaspectroscopicbinary(Vogel1903),whichhinted that thedimmingmightbeaneclipse.LaterapplicationofHenryNorrisRussel’sbinarystartheory(Russell1912a,1912b)cametoastrikingrevelation:thecompaniontotheF-typesupergiantwasnearlyequalinmass,yetspectroscopicallyinvisible(Shapley1915). Overthenextdecadeseveraltheorieswereadvancedtoexplainthisstartlingconclusion (for example, Ludendorff 1912; Kuiper et al. 1937; Schoenbergand Jung1938;Kopal1954); however, itwasHuang (1965)whoproposedthat the eclipse was caused by a disk of opaque material that enshroudedthe secondary component.Although Huang’s analytic model replicated theeclipselightcurve,thedisktheoryremainedunprovenuntilBackman(1985)detectedan infraredexcess that corresponded toa500Kblackbody source.Recently,thedisktheorywasvindicatedbyinterferometricobservationsoftheeclipse.TheseimagesshowtheF-starispartiallyobscuredbyadiskofopaquematerial(Kloppenborget al.2010,2011)whichisresponsibleforthedimmingobservedphotometrically. Althoughmostresearchonthissystemconcentratedontheeclipseitself,afewworkshavelookedatthesystemoutsideofeclipse.Sincetheearly1900s,ithasbeenknownthattheF-starexhibits0.1-magnitudevariationsinV-bandoutsideofeclipse.Indeed,theearliestdiscussionoftheseout-of-eclipse(OOE)variationswerebyShapley(1915,p.20).HecommentsonvariationsinvisualphotometrywithanamplitudeofDVis=0.3magnitude.Becauseobservationalerrorswerenotfullycharacterized,Shapleytreatedtheseresultswithcaution.Later, Güssow (1928) spotted aDVis = 0.15-magnitude variation outside ofeclipse that was corroborated by two photoelectric photometers (Shapley1928),therebyconfirmingthepresenceoftheOOEvariations.Shapley(1928)concludedthatthesevariationsarosefroma~355-dayquasi-periodicvariation;however,theexactperiodwaspoorlyconstrainedbythesedata. Afterthe1983–1985eclipse,Kempet al.(1986)proposedthata~100-dayperiodmayexistinpolarimetrydata.Later,Henson(1989)showedtherewaslittletonowavelengthdependenceinthevariations,implyingthatthesourceofpolarizationisThompsonscatteringfromfreeelectrons.Inhisdissertation,HensonfoundintervalswheretherewerevariationsinStokesQ,butlittletonothinginStokesU.ThiswasinterpretedtobecausedbytheF-starhavingtwomajoraxesforpolarization,inclinedatanangleof45degreeswithrespecttoeachother.Likemanyoftheotherstudies,avisualinspectionofHenson’sdatashowedthatsomelongtrendsmayindeedexist,butnothingwasstrictlyperiodic.From the post-eclipse polarimetry, Henson concluded that the photometricand polarimetric variations might be caused by non-radial pulsation in low-order ℓ=1,2m=±1modes.ThisnotionissupportedbytherecentautomatedclassificationofeAurasanaCygvariable(Dubathet al.2011a).


After the1985eclipse,manyauthors sought todetermineperiodsof theOOEvariation.Usingdatafromthefirstfiveyearsaftertheeclipse,Nhaet al.(1993)foundoccasionalstablevariationalpatternswouldsetin(inparticulararoundJD2447085–2447163)withDU=0.27,DB=0.17,andDV=0.08,andacharacteristicperiodof95.5days.Later,HopkinsandStencel(2008)analyzedtheirinter-eclipseV-bandphotometricdatausingtheperansosoftwarepackage(Husar2006).They found twodominantpeaks in theFourierpower spectrawith65-and90-dayperiods. PerhapsthemostcomprehensiveperiodanalysiseffortwasmadebyKim(2008).TheyusedtheCLEANestFouriertransformalgorithm(Foster1995)andtheWeightedWaveletZ-transform(WWZ;Foster1996)onnearly160yearsofphotometryofeAur.UsingthesetwoalgorithmstheyidentifiedseveralperiodswhichledthemtoconcludeeAurmaybeadoubleormulti-periodicpulsator. Hereweextendtheworkofourpredecessorsbyanalyzingtwenty-seven-years worth of inter-eclipse UBV photometry. In the following sections wediscuss our sources of data, our analysis methods, and the results. We thenconcludewithadiscussionofourresultsinastellarevolutioncontext.

2. Data sources

2.1.Historicphotometry e Aur has a rich history of photometric observations. We conducted acomprehensiveliteraturereviewandfoundtwenty-sevensourcesofphotometryfromeighty-onedifferentobservers.WedigitizedallofthesedataandintendtosubmitthemtotheAAVSOInternationalDatabaseorVizieR(whencopyrightallows)afterthepublicationofthisarticle.Afulldiscussionofthedatasources,assumed uncertainties, and digitization methods is in Kloppenborg (2012);however,wehavesummarizedtheimportantaspectsofthesedatainTable1.

2.2.Phoenix-10 The Phoenix-10 Automated Photoelectric telescope, designed by LouisBoyd,obtainedatotalof1,570U-,1,581B-,and1,595V-bandobservationsofeAurbetween1983and2005.Thesystemconsistedofa1P21photomultipliermountedona10-inchf /4Newtoniantelescope.AdetaileddescriptionofthissetupcanbefoundinBoydet al.(1984b).ThetelescopewasoriginallylocatedindowntownPhoenix,Arizona,untilitwasmovedtoMountHopkinsduringthe summer of 1986. The system was then moved to Washington Camp inPatagonia,Arizona,in1996whereitoperateduntil2005. TheearliestdataoneAurwereobtainedin1983Novemberandcoveredmostofthe1983–1984eclipse(Boydet al.1984a).ThesedatacoverintervalsJD2445646–2455699(Breger1982,file131),JD2445701–2445785(Breger1985, file 136), and JD 2445792–2445972 (Breger 1988, file 137) (1983November 3–1984 September 29). Although the photometer collected data


between1984Septemberand1987September,theoriginaldatawerelostduetoahardwarefailure(Boyd2010).Asfaraswehavebeenabletodetermine,these data were not published in subsequent issues of the IAU Archives of Unpublished Observations of Variable Stars. In addition to these data, ourpublication includes unpublished data from theAPT-10 which starts on JD2447066(1987September27)andendson2453457(2005March27). The standard observing sequence for e Aur was KSCVCVCVCSK(K=Check,S=Sky,C=Comparison,V=Variable)iteratingthroughtheUBVfilters(seeBoydet al.1984b,Table1)with10-secondintegrations.Informationonthetarget,check,andcomparisonstarsaresummarizedinTable2.Thesedifferentialmeasurementswerecorrectedforextinctionandtransformedintothe standard UBV system. The automated reduction pipeline discarded anyobservationswithaninternalstandarderrorof±20milli-magnitudesorgreater.Typicalexternalerrorsare±0.011,±0.014,±0.023magnitudeinV,B,andUfilters,respectively,withmeaninternalerrorsof±0.005,±0.005,and±0.009(StrassmeierandHall1988).Thestabilityofthesystemhasbeensatisfactoryondecade-longtimescales(HallandHenry1992;Hallet al.1986).

2.3.HopkinsUBV Co-authorJeffreyHopkinscollected811U,815B,and993VdifferentialmagnitudesattheHopkinsPhoenixObservatory(HPO)inPhoenix,Arizona.Thedataconsistoftwolargeblocks:thefirstbeganon1982September09andendedon1988December23,andthesecondseriesstartedon2003December04andendedon2011April25.AtthistimethephotometricprogramatHPOended. TheHPOsetupconsistedofa1P21photomultipliermountedtoan8-inchCelestron C-8 telescope with standard Johnson UBV filters. Observationsof eAur were conducted in CSVSCSVSCSVSCS format, each composedof three10-second integrations inoneof the three filters.Nightlyextinctioncoefficientsweredeterminedandapplied.Colorcorrectionwasdeterminedonamonthlybasis.Afterthe1980observingseason,lAurigaewasusedasthesolecomparisonstar.TheassumedmagnitudesforlAurigaewereV=4.71,(B–V)=0.63,and(U–B)=0.12.AsubsetofthesedatahavebeendiscussedinChadimaet al.(2011).

2.4.AAVSOBrightStarMonitor Startingon2009October16,eAurwasplacedontheAmericanAssociationofVariableStarObservers’BrightStarMonitor(BSM)observingprogram.TheBSMconsistedof aTakahashiFS-60CBwith a field flattener; 60-mm f /6.2telescope and a SBIG ST-8XME camera with Johnson/Cousins BV Rc Ic andclearfilters.DatawerereducedbyArneHendenatAAVSOheadquarterstothestandardphotometricsystem.Allcolorandextinctioncorrectionswereappliedbefore data were submitted to theAAVSO International Database. OngoingobservationsfromthisinstrumentcanbefoundintheAAVSOdatabaseundertheobservercode“HQA.’’


2.5.Solarmassejectionimager Forthesakeofcompleteness,wealsomentionourworkondatafromtheSolar Mass Ejection Imager (SMEI; Simnett et al. 2003).Although SMEI’sprimarymission is tomap the large-scalevariations inheliospheric electrondensitiesbyobservingThompson-scatteredsunlight,italsocollectedprecisionphotometryon~20,000starswithV<8.Througheach102-minuteorbit,mostregions in the skywere coveredby a dozenormore frames throughoneofSMEI’sthreebaffled,unfilteredCCDcameras. The instrument was designed for 0.1% photometry and, when properphotometric extraction is performed, this precision was realized on starsbrighterthanfifthmagnitude.Onaveragetheuncertaintyonfainterstarswasproportionallyworsebytheratioofthestar’sbrightnesstofourthmagnitude,meaningfainteighthmagnitudestarsstillhavebetter-than-groundphotometryprecision.TheinstrumentwasoperationalfromlaunchuntilSeptember2011whenitwasdeactivatedduetobudgetconstraints.Ourworkwiththesedatawillbediscussedinafuturepublication.

3. Analysis

The sources of photometry listed above were very inhomogeneous;consisting of multiple filters, reduction methods, observatories, instruments,and even reference star magnitudes. We created a script that finds overlapsbetweentwodatasetsofthesamefilter,binsthedata,andthencalculatesthecoefficientsrequiredtoscale/offsetthedatatothesamequasi-systemusingaweightedleast-squarestechniqueusingthefollowingequation:

Ai = a + b Bj + c tj (1)

HereAiistheithentryinthereferencephotometryset,Bjisthejthentryinthecomparisonphotometrydatasetoccurringat time tj,a isazero-pointoffset,b accounts for non-Pogson magnitudes (present in only our earliest visualphotometricdata),andccorrectsforatime-dependentdriftofthecomparisonphotometryset. Inallof thefilteredphotometry,onlyawasrequired. In thevisual data, a and b were required.As our work here is concerned with thevariations,ratherthanabsolutelycalibratedphotometry,weselectedHopkinsU,BSMB,andBSMVasreferences.Offsets(a)betweenvariousphotometricsourcesaresummarizedinTable3. AftertheoffsetsweredeterminedwepassedthedatathroughtheWindowsimplementation of WWZ, winwwz. Here we have used data from the rangeJD2446000–2455000in10-daystepswithflow=0.004,fhigh=0.05,andDf=0.0001.OurWWZdecayconstantwas0.0125.


4. Results

In Figure 1 we plot the twenty-seven-years worth of inter-eclipse UBVphotometry from theAPT-10andHPOobservatories.TheVdatahavebeenplotted unaltered, but U have been offset by –1.3 magnitude and B by –0.8magnitude.Internalphotometricuncertainties(~10milli-magnitudes)areaboutthe thickness of the lines. Each observing season consists of approximately200daysofdatawithbi-nightlysamplingfollowedby165-daygapswherethestarwasnotvisibleatnight.AllofthedatawerecorrectedforextinctionandtransformedtothestandardUBVphotometricsystem.Avisualinspectionofthedatarevealsnosingleconsistentperiodispresent. Historically,therehavebeenseveralreportedinstancesofshort-term(thatis,few-daylong)eventswhichwesuspectareflares.AlboandSorgsepp(1974)reportedaDU=0.2,DB=0.1,andDV=0.06brighteningthatlastedfivedaysaroundJD2439968 (1968April21).Similarly,NhaandLee (1983)notedarapid (few hour) 0.4 magnitude rise in the blue filter and 0.2 magnitude intheyellowfilteronJD2445356(1983January21).Wehavenoticeda two-nightflareinourdatasetstartingonJD2446736(1986November01).Thisevent resulted inaDU=0.2,DB=0.1, andDV=0.7photometric increase,strangelyoppositeofhistoricrecords.ContinuedUBVphotometryappearstobeaefficientwayofdetectingtheseevents. InFigure2weplotthecurrenteclipselightcurveinUBVRIJHfiltersfromtheabovesourcesandtheAAVSOdatabase.Wenotethattheeclipseappearsto be slightly wavelength-dependent, particularly from mid-eclipse to thirdcontact.ThiscanbeseenfromthedownwardslopeoftheU-banddataandflattrendinH-band.WesuggestthisisduetoadditionalsmallparticlescomingintothelineofsightfromasublimationzoneontheF-starfacingsideofthedisk. InFigures3through5weplottheWWZresultsfortheU,B,andVfilters,respectively.ThecolorinthesefiguresistheWWZoutputwithhighervalueindicatingstrongerpresenceofthatparticularperiod.BecausetheAPT-10wasnotoperationalduringtheintervalJD2449500–JD245000,weblockedouttheWWZresultinthisregion. Frominspectionofthesefigures,itisclearthatnosingleperiodcanaccuratelydescribe thevariations seen ineAur. InTable4we listpeakswhoseWWZcoefficientwasgreater than100. In theU-banddata the twomostdominantperiodsarecenteredat(8977,102.7)and(12259,87.9)(henceforththe“uppertrack’’).Thesepeakswerespacedapartby3,282dayswithDP=–14.8days.WhentheWWZoutputwashigh,theradialvelocity(seeStefaniket al.2010fordata)andphotometricchangeswereinphase.Thecombinationofthesetwoeffectsleadustobelievetheseeventsshouldberegardedassignificant. OperatingontheassumptionthatthesepeaksprovidedaglimpseofperiodevolutionintheF-star,weintentionallysoughtvariationsfollowingaparallelevolutionary path. Three peaks located at (7166, 90), (10492, 82.7), and


(13744,68.9)(hereafterthe“lowertrack’’)followedasimilarevolution.Likethe“uppertrack,’’thesepeakswereseparatedbynearly3,300days. PeaksattheselocationsalsoappearedintheB-andV-banddata,althoughwithmuchlowersignificance.TheWWZvalueinwinwwzwasdeterminedbyac2-likemetricthatdoesnotconsidertheuncertaintiesinthedata.Thereforethe additional scatter seen in adjacent B or V photometry, although withinuncertainties,resultsinalowerWWZvalue.Thehigheramplitudesandgreaternight-to-nightconsistencycauses theUdata tohave largerWWZvalues,onaverage,thantheBandVdata. IntheB-bandWWZ,weseeafewpeaksinthe80-to100-dayrangeappearingfromtimetotime,althoughtheyareclearlynotstable.Likewise,intheV-bandWWZthereisasingledominantpeakof(6100,90),butotherwiselittlehintofastablevariationalpattern.WedonotsuggesttheWWZ<100resultsshouldbegivenmuchconsideration;however,intherangeJD24450000–24455000therewereseveralcommensurateperiodsthatappearedtoevolvedownwardatarateofseveraldays/year. InTable5weusedtheaboveobservationsasaguideandpredicteddateswhenstablepulsationalpatternsshoulddevelopand theirperiods.Wenotethat the118-dayperiodaroundJD2445695(near thirdcontactof the1984eclipse)didnotmanifest;however,neartheendofthe2009–2011eclipseasawtooth-likepatternwitha61-to76-dayperioddeveloped(seeFigure2).Thisistantalizinglyclosetothe~73-dayperiodwepredictedwoulddevelopatthistime. To test our extrapolation, we attempted a WWZ analysis on the visualdata.Theonly set that spannedanentire inter-eclipse intervalwascollectedbyPlassman(Güssow1936).Datawithin the interval2422000–2428000(seeFigure6)clearlyshowthepresenceoftheOOEvariationswithcharacteristicperiodsof330–370days.Thisvaluewasnearly100dayslongerthanwhatwepredictforthistimeinterval,implyingourextrapolationshouldnotberegardedashighlypredictiveuntilfurtherperiodcharacterizationisconducted.

5. Discussion and conclusion

Wehavecreatedthefirstlong-termUBVphotometricrecordofeAurusingthe data from the APT-10 and HPO observatories. These data show stablevariationalpatternsdevelopedon3,200-daytimescales.IntheU-bandWWZoutput,wehaveidentifiedtwoparalleltracksofstablevariationsthatevolveatarateofDP=–1.6day/yearandDP=–1.2day/yearfor the“upper’’and“lower’’ track, respectively. Extrapolating these results, we have identifieddates at which we anticipate stable variational patterns will manifest andpredictedtheperiodsthattheyshouldhave.OurextrapolationtoJD2455541predictsa73-dayperiodshouldhavedeveloped;itistantalizinglyclosetothe61- to76-dayperiod thatwasobservedduring the second-halfof the2009–


2011eclipse.Ourinterpretationbelowisbasedonthis“two-track’’notionandlikelyunderestimatesthetruecomplexityinthissystem.InTable4weprovideallpeakswithaWWZ>100fortheUBVphotometryinhopesthattheywillbeusefultofutureresearchers. At the time of this writing, a consistent asteroseismic interpretation forevolvedsupergiant-classstarsdoesnotexistduetotheuncertaintiesunderlyingthetheoreticalcalculationsofmixingtheoryandradiationpressure(Aertset al.2010,ch.2).Therefore,wecannotprovidearigorous,quantitativeinterpretationof the periods which we have observed. Instead, we interpret the observedperiodsqualitativelybycomparing themwithobserved supergiant andpost-AGBbehavior.Regrettably,fewcomparativestudiesofF-typesupergiant/post-AGBstarsexist,especiallymulti-decadesurveys.Thereforeourinterpretationsareinherentlybiased.Wehaveattemptedtodiscussthesebiasesthroughlyandindicatewhereourstudycouldbenefitfromfutureresearch. It had been known for some time that stars near the F0Ia spectral andluminosity class show low-level variations with 0.015–0.025 magnitudeamplitudes in theV-band (Maeder 1980).An investigation by van Leeuwenet al.(1998)oftwenty-foursuper-andhyper-giantstarsfromtheLMC,SMC,andtheMilkyWayusingHIPPARCOSphotometryshowedthatalloftheseBto late-Gstarsexhibitedphotometricchanges thatwerenot strictlyperiodic.Indeed, many of these “periods’’ would be better described as “quasi-’’or “pseudo-periods.’’Across this region of the HR diagram, stars tended toshowvariationson10-to100-daytimescales. Indeed,inthisrespecteAurcouldeasilyberegardedasarecently-evolvedsupergiant.SeveralstarsinthevanLeeuwenet al.(1998)samplewereaclosematch for eAur:At a slightly higher temperature, HD 269541 (HIP 25448,A8:Ia+, in the LMC) hasDVT = 0.1-magnitude variations with several shortperiods in the8- to 40-day interval, and two longer periods at 146 and182days. The slightly cooler HD 269697 (HIP 25892, F5Ia, in the LMC) hadtwoequallysignificantperiodsat48and84dayswithphotometricvariationsbetween0.01and0.05magnitudeinDVT.HD74180(HIP42570,F2Ia,intheMilkyWay)wastheclosestmatchtoeAurinthevanLeeuwenet al.(1998)sample.Thisstarshowedquasi-periodsat53,80,and160dayswithvariationsof0.06magnitude.ItisalsoworthmentioningthatanautomatedphotometricclassificationschemeconsideredeAurtobeanaCygvariable(Dubathet al.2011),aclassofluminoussupergiantsundergoingnon-radialpulsation. Post-AGBstarsmakeupaveryheterogeneousclassofobjects,thereforeit is difficult to discuss their properties, let alone discuss any reasons formembership (or lack thereof) for one particular star. We have searched the“ToruncatalogueofGalacticpost-AGBandrelatedobjects’’(Szczerbaet al.2007)forsystemsofsimilarspectraltypeandidenticalluminositiestoeAur.Thebest-matchisARPup(F0Iab,HIP39376)whichfeaturesmulti-periodic(RVb)pulsationwithDV=0.5andtimescalesof76.4±4-and1,250±300-


dayperiods(Kisset al.2007).Althoughthetimescalesmatch,thevariationalpattern (that is, highly predictable, stable) does not match what is seen ineAur.LikewisethepatternseeninthecoolerV340Ser(HD158616,F8)hassimilar timescales (87.7dand131d,Arkhipovaet al.2011),but isobviouslymulti-periodicandeasilypredicted.Tocompleteourviewofvariationsseenaround the F0Ia class, long-term photometric studies of the post-AGB starsIRAS10197-5750(A2Iab:e,2MASSJ10213385-5805476),IRAS16206-5956(A3Iab:e, 2MASS J16250261-6003323), IRAS 06530-0213 (F0Iab, 2MASSJ06553181-0217283),HD101584(F0Iabpe,HIP56992),andHD187885(F2/F3Iab,IRAS19500-1709)wouldbebeneficial. Aggregate statisticsofpost-AGBstars imply systemsof similar spectraltypes to e Aur have significantly shorter periods than their supergiantcounterparts.Forexample,Hrivnaket al.(2010)studiedaseriesofC-richpost-AGBstarsandfoundastrongcorrelationbetweentheeffectivetemperatureandperiod.Therelationshippredictsthathigher-temperaturepost-AGBswillhaveshorterperiodsfollowingalineartrend:DP/DTeff=–0.047dayK1.TheirFigure18suggestedeAurshouldexhibitvariationswitha~40-daytimescale,afactorof1.7 less thanwhatwehaveobserved.TheirworkonO-richstarsappearstobeforthcoming(seeShawet al.2011).Inasampleoffivepost-AGBstarsArkhipovaet al.(2011)foundasimilartrend.TheirFigure8predictsperiodsof~65days,afactorof1.25to1.5shorterthanwhatwehaveobserved.Amajorityof theirprogramstarsalsoweremultiperiodic,with ratiosofP1/P2~1.03 to1.09,whereaseAurshowsahigherratioof1.24to1.27. UntilthispointwehavecomparedthevariationalpatternsineAuragainstsinglestars.Asnotedabove,thestablevariationpatternsdevelopat3,200-dayintervals, which is nearly 1/3 of the 27.1-year (9,890-day) orbital period. Itwould appear the companion is influencing the pulsational properties of theF-star.As theorbit is eccentric (e ~0.227ore ~0.249–0.256,Stefaniket al.2010,Chadimaet al. 2010, respectively)onemight anticipate tidal flows tobe induced in the F-star’s tenuously-bound atmosphere (log g ~1, Sadakaneet al.2010)duringperiastronpassage;however,dissipationtimescaleswouldcertainly be less than the nine-year interval seen between stable variationalpatterns(seeMorenoet al.2011,andreferencesthereinforadiscussionofthetheoreticalframework).InsteadwespeculatethatgravitationalforcingduetoorbitalmotionisexcitingnaturalresonantfrequenciesintheF-star(thistheoryisshowntobepossibleinmainsequenceobjects—seeGoldreichandNicholson1989;Rocca1989;WitteandSavonije1999a,1999b;Zahn1975,1977).Thisconjecturepredictsthattheexcitationsshouldrepeatatthesameorbitalphasesandisthereforetestablebycontinuedphotometricmonitoring.Thenextdateswhen sucheventsmighthappenare JD~2457000 (2014December) and JD~2457000 (2019 December).The development of a consistent asteroseismictheoryforsupergiantsmayprovideanearliertestofourhypothesis. Given this information and the photometric behavior discussed above,


we consider it unlikely that the F-star is a post-AGB object and conclude,on a qualitative basis, that the F-star is more likely a traditional supergiant.Implicationsfortheevolutionarystateandphysicalpropertiesofthediskwillbediscussedinforthcomingpublications.

6. Acknowledgements

ParticipantsfromtheUniversityofDenveraregratefulforthebequestofWilliamHershelWombleinsupportofastronomyattheUniversityofDenver.They acknowledge support from National Science Foundation through ISEgrantDRL-0840188(CitizenSky)totheAmericanAssociationofVariableStarObserversandASTgrant10-16678totheUniversityofDenver.Weacknowledgewith thanks the variable star observations from the AAVSO InternationalDatabasecontributedbyobserversworldwideandusedinthisresearch.Thisresearch has made use of NASA’sAstrophysics Data System BibliographicServicesandtheSIMBADdatabase,operatedatCDS,Strasbourg,France.

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Lu

dend

orff

(190

3)

Arg

elan

der

2393

950

2404

492

56

St

Lu

dend

orff

(190

3)

Hei

s23

9451

124

0025

278

St

Lude

ndor

ff(1

903)

O

udem

aüns

23

9849

023

9905

816

St

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ff(1

903)

A

rgel

ande

r24

0395

024

0449

256

St

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ff(1

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Sc

hoen

feld

24

0404

924

0598

829

St

Lude

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ff(1

903)

Sc

hwab

24

0661

424

1624

565

St

Lude

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ff(1

903)

Pl

assm

an

2408

093

2414

961

85

St

Lu

dend

orff

(190

3)

Saw

yer

2409

147

2413

645

50

St

Lu

dend

orff

(190

3)

Porr

o24

1136

024

1139

13

St

Lu

dend

orff

(190

3)

Luitz

et

2414

288

2416

217

55

St

Lu

dend

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(190

3)

von

Pritt

witz

24

1458

424

1608

018

Pm

Lude

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ff(1

903)

Pl

assm

an

2415

259

2416

223

29

St

Lu

dend

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(190

3)

Kop

ff24

1570

924

1582

56

St

Lu

dend

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(190

3)

Goe

tz

2416

107

2416

196

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2395

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2406

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109

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2416

574

2419

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41

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2416

574

2419

691

26

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uffe

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24

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2417

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97

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G

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w(1

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N

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d(1

)24

1348

824

1428

022

St

Güs

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(193

6)

Plas

sman

24

1638

024

2778

543

0St

Tabl

e1.

All

sour

ceso

fpho

tom

etry

(his

toric

and

new

).

Sour

ce

Obs

erve

ra JD

Sta

rt

JD E

nd

Obs

. Ty

peb

Not

es

Tabl

e co

ntin

ued

on fo

llow

ing

page

s


G

üsso

w(1

936)

En

ebo

2416

425

2417

326

31

St

G

üsso

w(1

936)

W

ende

ll24

1657

424

1969

125

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sow

(193

6)

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ller

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848

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973

12

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G

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w(1

936)

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hner

t24

1732

624

1749

85

St

G

üsso

w(1

936)

Sc

harb

e(1

)24

1782

424

1865

312

St

Güs

sow

(193

6)

Hor

ning

24

1819

224

2058

951

St

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sow

(193

6)

Mun

dler

24

1832

324

1865

713

St

Güs

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(193

6)

Lau

2419

275

2429

779

16

St

G

üsso

w(1

936)

M

enze

24

2003

124

2095

839

St

Güs

sow

(193

6)

Gut

hnic

k24

2014

724

2017

510

Pe

Güs

sow

(193

6)

Joha

sson

24

2268

724

2337

412

St

Güs

sow

(193

6)

Gut

hnic

kan

dPa

vel

2422

940

2423

361

27

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G

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w(1

936)

G

adom

ski

2423

016

2427

060

31

St

G

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w(1

936)

G

raff

2424

251

2425

957

13

Pm

G

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w(1

936)

K

ordy

lew

ski

2424

647

2425

953

29

St

G

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w(1

936)

G

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w

2424

808

2427

762

145

Pm

G

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w(1

936)

K

ukar

kin

2425

100

2426

242

34

St

G

üsso

w(1

936)

B

eyer

24

2512

624

2619

644

St

Güs

sow

(193

6)

Dan

jon

2425

139

2426

636

34

Pm

G

üsso

w(1

936)

Ja

cchi

a24

2517

724

2621

041

St

Güs

sow

(193

6)

Paga

czew

ski

2425

185

2426

034

13

St

G

üsso

w(1

936)

Sc

harb

e(2

)24

2523

724

2610

415

St

Tabl

e1.

All

sour

ceso

fpho

tom

etry

(his

toric

and

new

),co

nt.

So

urce

O

bser

vera

JD S

tart

JD

End

O

bs.

Type

b N

otes

Tabl

e co

ntin

ued

on fo

llow

ing

page

s


Tabl

e1.

All

sour

ceso

fpho

tom

etry

(his

toric

and

new

),co

nt.

So

urce

O

bser

vera

JD S

tart

JD

End

O

bs.

Type

b N

otes

Tabl

e co

ntin

ued

on n

ext p

age

G

üsso

w(1

936)

St

ebbi

nsa

ndH

uffe

r24

2526

724

2646

798

Pe

Güs

sow

(193

6)

Tsch

erno

v24

2529

624

2609

025

St

Güs

sow

(193

6)

Mra

zek

2425

322

2425

857

4Pm

Güs

sow

(193

6)

Nijl

and

(2)

2425

322

2426

436

40

St

G

üsso

w(1

936)

D

ziew

ulsk

i24

2536

424

2609

622

St

Güs

sow

(193

6)

Men

ze2

2425

529

2426

065

23

St

G

üsso

w(1

936)

K

opal

24

2592

524

2646

518

St

Embe

rson

eta

l.(1

938)

2428

903

2428

920

7B

road

band

-IR

N

otu

sed

Th

iess

en(1

957)

2435

374

2435

942

10

yello

w,bl

ue,v

iole

t

Lars

son-

Lean

der(

1959

)

2435

428

2436

334

121

PV

W

idor

n(1

959)

2435

128

2436

295

122

yello

w,bl

ue

Not

use

d

Fred

rick

(196

0)

24

3476

124

3590

314

3Pe

,4c

olor

N

ottr

ansf

orm

ed

Lars

son-

Lean

der(

1962

)

2436

457

2437

023

52

PV

K

opyl

ova

nd

K

umai

goro

dska

ya(1

963)

2435

111

2436

695

251

PV

M

itche

ll(1

964)

U

BV

RIJ

HK

LN

Not

use

d

Low

and

Mitc

hell

(196

5)

UB

VR

IJH

KLN

N

otu

sed

St

ub(1

972)

2438

755

2439

925

220

Pe,1

0co

lor

A

lbo

and

Sorg

sepp

(197

4)

24

3994

724

3998

814

4U

BV

Alb

o(1

977)

2440

460

2440

548

42

UB

V

B

rege

r(19

82,1

985,

198

8)

24

4564

624

4597

245

3U

BV

B

oyd,

IAU

JA

POA

(198

3)

24

4523

924

4540

912

3U

BV


B

ackm

ane

tal.

(198

4)

24

4426

924

4538

210

7JH

KL’

MN

Q

B

hatt

eta

l.(1

984)

2445

044

2445

798

84

BV

RIJ

HK

Hop

kins

UB

V(1

)

2445

222

2447

520

1140

U

BV

Flin

eta

l.(1

985)

2445

065

2445

937

330

UB

V

Pa

rthas

arat

hya

nd

Fru

eh(1

986)

2445

208

2445

426

983

UB

V,uv

by

B

oyd

UB

V

24

4706

624

5345

747

46

UB

V

Unp

ublis

hed

C

hoch

ola

nd Žižovský (1987)

2445043

2445664

207

UBV

St

rass

mei

ere

tal.

(199

9)

24

5039

624

5042

721

6by

Tara

nova

and

S

hena

vrin

(200

1)

24

4503

224

5165

224

3U

BV

RJH

KLM

D

ownl

oad

from

CD

S

Hop

kins

UB

V(2

)

2452

979

2455

678

1836

U

BV

AAV

SOB

SM

24

5512

2pr

esen

t96

0B

VR

Ia I

dent

ified

onl

y if

from

a c

ompi

latio

n so

urce

. b The

pho

tom

etri

c sy

stem

use

d or

one

of t

he fo

llow

ing:

St =

Ste

p m

agni

tude

s (m

echa

nica

lly a

ssis

ted

visu

al d

ata)

, Pm

=

Pho

tom

etri

c, P

e =

pho

toel

ectr

ic, a

nd P

V =

pho

tovi

sual

. Se

e or

igin

al re

fere

nce

for f

urth

er d

etai

ls.

Tabl

e1.

All

sour

ceso

fpho

tom

etry

(his

toric

and

new

),co

nt.

So

urce

O

bser

vera

JD S

tart

JD

End

O

bs.

Type

b N

otes


Table2.StarinformationforBoydphotometricdata. Object R. A. Dec. Epoch Role* Other Names h m s ˚ ' "

HD34411 051908 400557 2000 K HR1729,SAO40233 HD32655 050650 431029 2001 C HR1644,SAO40029 HD31964 050158 434924 2002 V HR1605,SAO39955 Sky 050424 432957 2003 S* Role: K = Check, S = Sky, C = Comparison, V = Variable

Table 3. Offsets between observers. “ref” indicates this was the referencephotometrysetfortheassociatedcolumn. Source U B V

1983Boyd 6.944964 6.704575 5.955698 1984Hopkins –0.022894 –0.056568 –0.075453 1987Boyd –0.124972 –0.007964 –0.043503 2011Hopkins ref –0.045311 –0.044434 2011AAVSOBSM N/A ref ref

Table4.PeakperiodsobservedintheUBVWWZtransformsroughlygroupedbydate.Dateshavebeenroundedtothenearest10.PeriodsandWWZoutputareroundedtointegervalues.MJD=JD–2440000. U B V MJD Period WWZ MJD Period WWZ MJD Period WWZ

6180 83 210 6210 90 224 6170 91 478 7170 90 171 7200 76 86 7180 68 44 7840 75 327 7850 78 220 7350 66 43 — — — — — — 7620 52 41 — — — — — — 7820 83 171 8320 82 112 8400 75 180 8400 85 123 8590 163 65 — — — — — — 8980 102 400 — — — — — — 9160 99 270 9060 98 171 9160 98 80 — — — 9360 85 46 9380 94 66 — — — — — — 10150 61 158 10490 83 254 10510 85 114 — — — 10930 217 140 10920 212 158 10920 208 139 11220 122 112 11250 123 93 11390 123 92 11400 123 110 11410 123 108 — — —



Table 5. Predicted dates of stable pulsation features and their periods baseduponextrapolationoftrendsdiscussedinsection4. Upper Track Lower Track JD Period Observed? JD Period Observed?

2396465 340 2397831 249 2399747 325 2401120 239 2403029 310 2404409 228 2406311 295 2407698 218 2409593 280 2410987 207 2412875 266 2414276 196 2416157 251 2417565 186 2419439 236 2420854 175 2422721 221 2424143 165 2426003 206 2427432 154 2429285 192 2430721 144 2432567 177 2434010 133 2435849 162 2437299 123 2439131 147 2440588 112 2442413 132 2443877 102 2445695 118 2447166 90.0 Y 2448977 102.7 Y 2450492 82.7 Y 2452259 87.9 Y 2453744 68.9 Y 2455541 73 2457026 66 2458823 58 2460308 52 2462105 43 2463590 37 2465387 29 2466872 22 2468669 14 2470154 7

Table4.PeakperiodsobservedintheUBVWWZtransformsroughlygroupedbydate.Dateshavebeenroundedtothenearest10.PeriodsandWWZoutputareroundedtointegervalues.MJD=JD–2440000,cont. U B V MJD Period WWZ MJD Period WWZ MJD Period WWZ

11690 175 87 11670 172 86 11680 172 70 12260 88 350 12220 89 128 12240 90 81 12550 119 270 12560 121 172 12540 120 147 12960 76 98 12930 75 126 12880 77 108 13250 159 123 13320 149 99 13270 150 62 13740 69 180 13770 69 150 13750 69 71 — — — 14260 208 69 14290 204 63 14300 139 117 14540 156 81 14540 156 71


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Figure 2. 2009–2011 eclipse of e Aur in UBVRIJH filters, JD 2454800–2456000(2008November29–2012March13), asmeasuredbyHopkins (UBV), theAAVSOBSM(BVRI),andAAVSOobserversBrianMcCandlessandThomasRutherford(JHdata).TheV-banddata areplotted asobserved, all other filtershavebeenoffset byanarbitraryamountfordisplaypurposes.Theeclipsemayberepresentedbyalineardecreaseinbrightnessof~0.7magnitude,followedbyaflatminimumandthenasharprisebacktoout-of-eclipsebrightness.Theout-of-eclipsevariationsaresuperimposedonthisprofileandresultin60-to100-daycycleswithcharacteristicamplitudesof~0.1magnitudeinU,decreasinginamplitudetowardslongerwavelengths.Noticeduringthesecondhalfof theeclipse theU-band lightcurveslopesdownward,whereas theH-bandhasanupwardslope.Thisatteststothefactthattheeclipsehadwavelength-dependentextinction.

Figure3.U-bandWWZperiod analysisofeAur (c=1.25E–2).The color indicatespowerassociatedwithagivenperiodataparticulartime,whereasthewhitedottracesthe dominant period at a particular time.The region JD2449500–2450000has beenblockedoutduetoalackofdata.Wecautionthereaderthatperiodswithin<200daysofthisregionmaynotbetrustworthy.Seesection4foradiscussionoftheperiodspresentandourinterpretations.


Figure4.B-bandWWZperiodanalysisofeAur(c=1.25E–2).SeedescriptioninFigure3.

Figure5.V-bandWWZperiodanalysisofeAur(c=1.25E–2).SeedescriptioninFigure3.

Figure6.VisualphotometryofeAurbyPlassman(inGüssow1936)showingtheintervalJD 2422000–2428000 (1919 February 10–1935 July 16) including the 1927 eclipse.Uncertainties,notplotted,are±1intheleastsignificantdigit(±0.01magnitude).TheOOEvariationsareclearlypresent.Typicalpeak-to-peak timesaredifficult to judge,exceptrightbeforethe1927eclipse,where330-to370-dayperiodsappeartobepresent.

Karlsson, JAAVSO Volume 40, 2012668

V-band Light Curve Analysis of e Aurigae During the 2009–2011 Eclipse

Thomas KarlssonAlmers väg 19, 432 51 Varberg, Sweden; [email protected]

Received August 19, 2011; revised October 28, 2011, November 9, 2011; accepted November 14, 2011

Abstract Timings for the eclipse contactpoints andmid-eclipse, lengthofingress and egress, average magnitude during eclipse, and timings for out-of-eclipsevariationshavebeendeterminedintheVbandforthelongperiodeclipsingbinaryeAurigaeduringthe2009–2011eclipse.ThishasbeendonewithdatafromtheInternationalEpsilonAurigaeCampaign2009andAAVSO.Comparisonwithdatafrompreviouseclipseshasalsobeenmade.

1. Introduction

Theextremelylong-periodeclipsingbinaryeAurigae(period=~27.1years)is stillnot fullyunderstood. Ithasbeenstudiedbymanygroups indifferentwavelengths photometrically, spectroscopically, and interferometrically. The~2-yeareclipsethatoccurred2009–2011presentedanopportunitytoconstrainsomeparametersforthesystem.Asthesystemisbright(V=2.9–3.8)andthedurationoftheeclipseislong,it isasuitabletargetforamateurastronomerswhocancommitalongperiodoftimeforthistypeofproject.Aninternationalcampaign with participants of both advanced amateur and professionalastronomerswasestablished(seethecampaignwebsiteathttp://www.hposoft.com/Campaign09.htmlforfurtherdetails.)PhotometricdatafromthiscampaigntogetherwithtwocontributorsfromtheAAVSO,whohavecoveredthewholeeclipse,arethebasisforthisanalysis.ThecampaignproduceddataintheU,B,V,Rc,Ic,J,andHbandsbutthisanalysisonlycoversthemoststudiedVband.

2. Method

Theobserversinthecampaignusedadiversityofequipmentandreductionmethods(Table1),fromphotometersmountedontelescopes,toCCD-cameraswithtelescopes,orcamera-lensesandstandarddigitalsingle-lensreflexcamerasonatripod.Thecampaignhaspublishedrecommendedreductionmethodsandcomparison stars to use. But the diversity in equipment and individuality inphotometric software and methods used have introduced some differencesamongtheobservers.Tomaketheobservationscomparabletoeachotherthefollowingmethodswereused. Priortotheanalysisallobservationsweredividedintogroupsoffour-day

Karlsson, JAAVSO Volume 40, 2012 669

periods.IneachgroupthemeanofmagnitudeandJDwerecalculated.Eachobserver’sindividualobservationswerethensubtractedfromthecorrespondingmeans,andthestandarddeviationofeachobserver’sdifferenceswascalculated.Observerswithtoomuchspreadintheirdata(SD>0.04)werethenexcludedaltogether,andsomeoutlying(>0.08fromthemean)individualpointsfromtheremainingobserverswerealsoremoved.Newfour-daymeansanddifferenceswerethencalculatedfortheremainingobservers.Fromthesenewdifferencesan offset for each observer was calculated, showing the difference for eachobserver’sdatasetand themeanforalldata.Thisoffsetwas thensubtractedfromeachobserver’sdataandnewone-andfour-daymeanswerecalculated.Thesecorrectedmeanswerethenusedinthefurtheranalysis.TheindividualobservationswiththeoffsetappliedareseeninFigure1,the4-daymeansareinFigure2andthe1-daymeansinFigure3. The offset is based on the assumption that each observer used a similarreductiontechniqueduringtheeclipse,butthechoiceofreductiontechniquesandcomparisonstarsdiffersamongtheobservers,sothateachdatasetistoahigherdegreeconsistentwithitselfthanwiththeotherdatasets.Theideaisthatbyusingthismethodofreconcilingthedatamorefinedetailsinthelightcurveshouldbeseen.

3. Results

3.1.Eclipsetimingsandmagnitude Thefourcontactpointsforatotaleclipsebetweentwosphericalbodiesaredefinedasbeginningofeclipse,beginningoftotality,endoftotality,andendofeclipse.InthecaseofeAurigaethemainstarispartiallyeclipsedbywhatissupposedtobeadustydiscseenalmostedgeon(Huang1965;Kloppenborget al.2011),givingrisetoanelongatedandellipticaleclipsingbodyfromourview.Contact2and3havethereforeforthissystemanambiguousdefinitionandnotthesamephysicalmeaningasforaclassicaleclipsingbinary.Forthissystemtheycouldbeinterpretedas thepointswhere theleadingedgeof theelongateddischascrossedthewholefaceofthemainstarandwherethetrailingedgeofthediscbeginstoleavethefaceofthemainstar. Thecontactpoints(Table2)wereestimatedusingalineartrendlineappliedtotheingress/egressfromFigure2andweredecidedbywherethelinecrossedthe out-of-eclipse mean magnitude of 3.035 (Hopkins 2011) and the meanduringtheeclipseof3.728.Somefurtherworkmaybedonetoproduceamoreprecisemodelofthecurveandthemeansbeforeandafterthecontactpointstoobtainmoreaccuratetimesforthecontacts.Atcontact2thecurveisespeciallysmooth,whichmakes thecontactpointhardtodefine.Contact3couldhaveoccurredaboutaweek later than the trend linesuggestsbecauseof theverysteepbeginningoftheegress.Figures4and5showthegraphsusedtoestablishthecontactpoints.


The totality phase after mid-eclipse is 0.027 magnitude brighter thanbeforemid-eclipse.Thebrightestpartofthetotalityisduringmid-eclipse,andthedimmest just beforemid-eclipse.Onaverage, thedimmestpart is in thebeginningandendoftotalityandthebrightestinbetween:

•Meanmagnitudeduringtotality: 3.728(meanoverJD2455208–2455616)

•Meanmagnitudeduring1stpartoftotality: 3.742(meanoverJD2455208–2455400)

•Meanmagnitudeduring2ndpartoftotality: 3.715(meanoverJD2455400–2455616)

•Eclipsedepth:0.693magnitude

•Lengthofingress:142±10days meandropofbrightness:0.0049±0.0003magnitude/day

•Lengthofegress:121±14days meanincreaseofbrightness0.0057±0.0007magnitude/day

•Mid-eclipse,meanofcontact1and4: JD2455401±6(2010July23)

•Midpointoftotality,meanofcontact2and3: JD2455411.5±6(2010August03)

•Eclipseduration,contact4–contact1:674±12days

•Totalityduration,contact3–contact2:411±12days

3.2.Out-of-eclipse(OOE)variations Besides the eclipse, the system shows a smaller variation of 0.1 to 0.2magnitudewithanirregularperiodof~2months(see,forexample,HopkinsandStencel2006forarecentstudybeforestartofthe2009eclipse).Theout-of-eclipsevariationsduringtotalitywerecalculatedbyapplyingafourth-orderpolynomialfittothedatapoints24and27daysaroundeachmaximaandminimausingthe1-dayaverages fromFigure3.ThemeantimesandmagnitudesfromthetwosetsareshowninTable3.Theerrorforthespecifieddatesisestimatedtobeonaveragewithin±2daysandthemagnitudewithin±0.01. Amplitude iscalculatedas thedifferencebetween themaximumand themeanofthetwoadjacentminima.Thefirstminimumcouldbeaffectedbytheingress.Theobservationsmade3–4weeksbeforeandaftersolarconjunction


thatoccurredonJD2455355(2010June07)arecontradictoryprobablybecauseof thedifficultobservingconditionsanddifferences inextinctioncalculationamongtheobservers.Thisgivesuncertaintytothedatafromminimum2andmaximum2.Duringminimum5thereisaflatpartofabout15daysbetweenJD2455510and2455525.Thelastmaximumbeforestartofegressisespeciallyshortandlow. TheslopeoftheOOE-variationsisbetween0.0012and0.0029mag/daywithameanof0.0022mag/day,alittlelessthanhalfoftheslopeduringingress/egress.

3.3.Ingressandegresscharacteristics DuringingresstherearehintsoftwoOOEvariationswithmaximaaboutJD2455080(2009September05)andJD2455160(2009November24),whichcanbeseeninFigure4inthepartsoftheingresscurvethatlieabovethelineartrend.AnotherOOEvariationjustattheendofingresswithamaximumaboutJD2455215(2010January18)isalsoprobableandcanbeseenasapartwithlowslopeattheendofingress. The egress started with a high rate of change in magnitude, during JD2455620to2455655(2011February27–2011April03).Thechangewas0.0089magnitude/day, the highest that was seen during the whole eclipse. FurtheranalysismustbedonetotellifarisingOOEvariationinteractedtogeneratethishighpace.AsthelastOOEvariationjustbeforeegresswasstrangelyshortand lowit ishard todecideby just lookingat the lightcurve ifanewOOEvariationoccurredduring thisperiod.DuringJD2455655 to2455670 (2011April 03–2011April 18) the slopewas lower, at 0.0051magnitude/day, andthentherewasastrangestandstillorslightdecreaseofbrightnessforabout15daysuntilJD2455685(2011May03).Afterthattheegresswentonatasteadyrateof0.0055magnitude/day,whichisaboutthesameasthemeanduringthewholeegress.Thefluctuationsthatcanbeseenat theveryendofegressareprobablycausedbythedifficultobservationconditionsduringthattimenearsolarconjunction.ThebigchangeofslopearoundJD2455655and the laterstandstillseemtoobigtobecausedbyanyOOEvariation.

3.4Comparisonwithpreviouseclipses InFigure6thereisacombinedlightcurvewiththe4-dayaveragedatafromFigure2togetherwithtwoprominentdatasetsfromtheprevioustwoeclipses,observationsbyGunnarLarsson-Leander1956–1957(Larsson-Leander1959)and Stig Ingvarsson 1982–1984 (Schmidke 1985). The elements from theGeneral Catalogue of Variable Stars(GCVS4;Kholopovet al.1984),epochJD2435629andperiod9,892days,wereusedtophasethedata.Table4showsdatafrompreviouseclipsestogetherwiththedatafromthispaper. Periodanalysesweremadewiththelightcurveandperiodanalysissoftwareperanso(Vanmunster2007)andtheANOVA(analysisofvariance)method.Theperiodscalculated(Table5)are2–5dayslongerthantheperiodfromGCVS4.


The trend of decreasing duration of eclipse and egress and increasingduration of totality that was seen during the three or four previous eclipsesisbrokenbythelasteclipse.Infact,the2009–2011eclipseresemblesthatof1955–1957morethanthatof1982–1984,withthemoresimilarlengthofthedifferentphases,thedeepminimumjustbeforemid-eclipse,andthekneehalfwayduringtheegress.In1984thekneewasnotvisibleuntilthesystemhadreachedmagnitude3.30–3.25andtheobservationseasonwasalmostover.Thelackofobservationsattheendofthe1984eclipseisprobablythecauseoftheveryshortegressstated,calculatedfromtheslopeseenatthefirstphaseofegress. Differencesarethedeepminimum,downto3.85,thatwasseenattheveryendoftotalityin1956butnotseeninthetwofollowingeclipses.ThefrequentOOEvariationsduringtotalityseenduring2010seemtonotoccurtothesameextenteither in1956or1983.Maybeitcanbepartlyexplainedbythemoredetailedobservationsdoneduringthelasteclipse. Thepronouncedmid-eclipsebrighteningthatwasevidentin1983wasnotseentoanyhigherdegreein2010.Althoughthebrightestpointduringthetotalityof 2010 occurred at mid-eclipse, it was only 0.02–0.04 magnitude brighterthanthetwosubsequentout-of-eclipsevariations.Itshouldalsobestatedthatthemid-eclipseof1984coincidedwiththetoughestobservationconditionsatsolarconjunction,andnoobservationsweremadeatthetimeofmid-eclipse.Ifacarefulcorrectionforextinctionisnotdoneduringthisperiod,onecouldeasilyobtainvaluestoobrightforeasthemostusedcomparisonstars,lAur,hAur,andHR1644,allliesouthofe.ThisappearancewasseenamongseveralobserversduringMay–June2010. InFigure6onecanalsonoticetheplacementofthehumpsfromtheOOE-variationsduringthetotalityphasebetweenthethreeeclipses.Formostparttheyarenotinphasebetweenallthreeeclipses,withtheexceptionofabrighterphaseatmid-eclipse.ItcontradictstheideafromFerluga(1990),thattheOOE-variationsarecausedbyring-likestructureswithCassini-likedivisionsintheobscuringdiscasitpassesthemainstar.Ifsucharingstructureisstableoneshouldexpectthatthehumpswouldbeinphasebetweentheeclipses.

4. Conclusions

Thefollowingconclusionscanbedrawnfromthisstudy: TheOOEvariationsoccurwiththesameamplitudeandperiodicityduringthe eclipse as the period before eclipse and make it much harder to see thefeaturesoftheeclipseitself. Ingressandegresshavedifferentlengths.Inthisstudyegressisabout20daysshorterthaningress.Comparedtopreviouseclipsesthisrelationhasvariedagreatdeal.Thelengthofegress,especially,hasfluctuatedalot. Theegresshasakneehalfwayswheretheslopechangesabruptly,achangethatis toobigtobeexplainedbyOOEvariations.Furtheranalysishastobe


donetoseeifthegeometryoftheeclipsingdisccanexplaintheshapeoftheegresslightcurveorifsomeotherprocessisinvolved. If the eclipsing body is an homogeneous elliptical disc, then in purelygeometricaltermsthebiggestlossoflightbyapartialeclipseshouldoccurhalfways,andthelightcurveduringtotalityshouldbeslightlyconvex.Instead,theaveragelightcurveisslightlyconcaveduringtotality.Thismeansthatanothermechanismmaybeinvolvedtoexplaintheshapeofthecurve,forexample,anopticallythinnercenterofthediscorsomesortofscatteringeffect. There is also a difference in mean magnitude during the first half oftotality compared to the second half that could be a real feature if OOEvariationsareomitted.

Acknowledgements

Thankstotheobserversforthecountlesshoursofworkspentoncollectingthedatathatthisanalysisisbasedon.ThanksalsotoJeffHopkins,whohasdoneagreatjobwithTheInternationalCampaignandwhocollectedandprovidedthedataforthisanalysis.AndthankstoChrisAllen,whohashelpedmegettheEnglishlanguageright.

References

Ferluga,S.1990,Astron. Astrophys., Suppl. Ser.,238,270.Hopkins,J.L.2011,“Photometrictiminganalysisofthe2009–2011eclipseof

EpsilonAurigae”(http://www.hposoft.com/EAur09/Analysis2011.pdf).Hopkins,J.L.,Schanne,L.,andStencel,R.E.2008,“GearingUpforEpsilon

Aurigae’sFirstEclipseoftheMillennium,”inThe Society for Astronomical Sciences 27th Annual Symposium on Telescope Science,heldMay20–22,2008atBigBearLake,California,Soc.Astron.Sci.,RanchoCucamonga,CA,67.

Hopkins,J.L.,andStencel,R.E.2006,“SingleChannelUBVandJHBandPhotometryofEpsilonAurigae,”inThe Society for Astronomical Sciences 25th Annual Symposium on Telescope Science,heldMay23–25,2006,atBigBear,California,Soc.Astron.Sci.,RanchoCucamonga,CA,13.

Huang,S.-S.1965,Astrophys. J.,141,976.Kholopov,P.N.,et al.1985,General Catalogue of Variable Stars,4thed.,Moscow.Kloppenborg,B.,et al.2011,posterattheSeattleAASmeeting11Jan2011,

“InterferometricImagesoftheTransitingDiskintheepsilonAurigaeSystem.”Larsson-Leander,G.1959,Arkiv Astron.,2,283.Schmidke, P. C. 1985, “UBV photometry of the 1982–4 eclipse of Epsilon

Aurigae:Adiscussionoftheobservedlightcurves,”inNASAConf.Publ.,NASACP-2384,67.

Vanmunster,T.2007,peransoperiodanalysissoftware,http://www.peranso.com.

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Table2.Timingoftheeclipsecontactpoints.

Contact JD Date

1 2455064±5 2009August20 2 2455206±5 2010January09 3 2455617±7 2011February24 4 2455738±7 2011June25

Table3.Dataforout-of-eclipsevariationsduringtheeclipse.

Minima Nr. JD Date Length V Mag.

1 2455259 2010March03 — 3.77 2 2455311 2010April24 52 3.79 3 2455367 2010June19 56 3.78 4 2455437 2010August28 70 3.72 5 2455520 2010November19 83 3.75 6 2455576 2011January14 56 3.75 7 2455610 2011February17 34 3.77

Avg 58.5 3.761

Maxima Nr. JD Date Length V Mag. Amplitude

1 2455283 2010March27 3.72 0.060 2 2455336 2010May19 62 3.71 0.075 3 2455407 2010July29 60 3.65 0.100 4 2455471 2010October01 63 3.67 0.065 5 2455547 2010December16 79 3.69 0.060 6 2455590 2011January28 43 3.74 0.020 7 — — — — —

Avg 61.4 3.697 0.063


Table4.Datafrompreviouseclipsestogetherwiththedatafromthispaper.

Mean of 1901–1903 1955–1957 1982–1984 2009–2011 1928-1930 (1) Gyldenkerne (1) Schmidtke

Duration(days) 714 670 647 674 Ingress(days) 182 135 137 142 Totality(days) 330 394 446 411 Egress(days) 203 141 64 121 Depth(mag) 0.80 0.75 0.686(2) 0.6931 From Hopkins, Schanne, and Stencel (2009). 2 Mid-eclipse brightening omitted.

Table5.PeriodscalculatedwithperansoANOVA.

Comparison Period (days)

1955-57,1982-84,2009-11 9897 1955-57,2009-11 9896 1982-84,2009-11 9894 GCVS4 9892

Figure1.Theindividualobservations,witheachdatasetcorrectedwithitsoffset.(TheobserverPWmadeobservationsfromtwodifferentobservatories.)


Figure4.DetailfromFigure2oftheingress(JD2455060–22455216)andthelinearfitused.Thedottedlinesshowanerrorof1sigmainmagnitude.

Figure3.TheobservationsfromFigure1,groupedtogetheras1dayaverages.

Figure2.TheobservationsfromFigure1,groupedtogetheras4-dayaverages.


Figure5.Detail from figure2of theegress (JD2455616–2455740)and thelinearfitused.Thedottedlinesshowanerrorof1sigmainmagnitude.

Figure6.Thedatafromthispaper(IEAC)comparedwithtwodatasetsfromtheprevious twoeclipses,GunnarLarsson-Leander (LLG) from1955–1957andStigIngvarsson(ING)from1982–1984.

Maraveliasetal., JAAVSO Volume 40, 2012 679

Report From the e Aurigae Campaign in Greece

Grigoris MaraveliasPhysics Department, University of Crete, GR-71003, Heraklion, Crete, Greece; address email correspondence to G. Maravelias at [email protected]

Emmanuel (Manos) KardasisDepartment of Electronics Engineering, T.E.I. of Pireaus, GR-12244, Egaleo, Greece

Iakovos-Marios StrikisPindarou 15, GR-12461, Chaidari, Greece

Byron GeorgalasAmeipsiou 12, GR-11143, Athens, Greece

Maria KoutoulakiPhysics Department, University of Crete, GR-71003, Heraklion, Crete, Greece

Received May 30, 2012; revised August 27, 2012; accepted September 5, 2012

Abstract WereporttheresultsoftheGreekcampaigntoobservethe2009–2011eclipseofeAurigae.WepresenttheactivitiesorganizedbytheHellenicAmateurAstronomyAssociation(HAAA)inordertopublicizetheeventandtoprovidethenecessaryinformationandtoolstobothfirst-timeandexperiencedobservers.Althoughvisualobservationswere thecoremethod,weproposedand experimented with various techniques. In total, data from 21 observerswere acquired combining different techniques: 302 visual, 95 CCD, and 11DSLRobservations,and5low-resolutionspectra. We were able to construct the light curve of the eclipse and extractsome interesting results, in agreement with previous studies. The system’sV-magnitude drops from ~3.0 to ~3.8 in 131±21 days.The ingress date isestimatedaround theMJD55087±15d (August12,2009)and thesystem isexitingeclipseaftertheMJD55797±15d(August23,2011).Weestimatethedurationofthe2009–2011eclipsetobe710±21days.Aratherpossibletrendformid-eclipsebrighteningexistsonly in theCCD/DSLRdata,which showoscillationsof0.07magnitudeamplitude.

1. Introduction

Thebright(~3V-magnitude)binarysystemeAurigae(eAur,R.A.05h01m58.1s,Dec.+43°49'23.9'',J2000)hasbeenalongmysterysinceitsdiscoveryin early 1800s. The binary consists of a F0 Iab star and a cool, mysterious

Maraveliasetal., JAAVSO Volume 40, 2012680

companionwhicheclipsesthesupergiantevery27.1yearsforalmost2years.Althoughthesystemhasbeenusedextensivelyasatestbedformanytheoriesandobservationalmethods(Carrollet al.1991;GuinananddeWarf2002,andreferencestherein)thedataobtainedsofar,whichextendalmosttwocenturies,havenotbeenadequatetofullyexplainthissystem.Evenafterthelasteclipseof 1982–1984, when an international campaign was launched, the mass andluminosityuncertaintiesremainedstrong,prohibitingthefinalsolution(Stencel1985).Butallthesedataprovideimportantconstraintsallowingtwopossiblescenarios:(i)thehigh-massmodel,wheretheF0starisconsideredayoungstarofmass~15M

ùandradius~200R

ùandtheeclipsingcompanionacool,proto-

stellarorproto-planetarydiskwithtotalmassofM~13.7Mù

andradius~9.3AU,(ii)thelow-massmodel,wheretheF0starisanoldsolarmasspost-AGBstarandthediskisaremnantofaccretionduetomasstransferwithatotalmassof~5M

ùandradius~7R

ù.Butbothmodelshavesevereproblemstofully

interprettheobservations,and,moreover,newdataraisenewquestions(Hoardet al.2010;Kloppenborget al.2010). In2009–2010thesystemwouldundergoanothereclipse,offeringagreatopportunitytoacquiremoreinformation.Thus,anotherinternationalcampaignhasbeenlaunchedinordertocoordinate,collect,andprovideallthenecessarymaterialtoperformscientificusefulobservationsfrombothprofessionalandamateur astronomers: the International e Aur Campaign 2009–2011 (http://www.hposoft.com/Campaign09.html) organized by Jeff Hopkins and RobertStencel,andtheCitizenSkyproject(http://www.citizensky.org)organizedbytheAmericanAssociation of Variable Star Observers (AAVSO; http://www.aavso.org). The contribution of amateur astronomers is considered valuablesincethesystemisbrightenoughtobeobservedbytheirequipment(evenwithunaidedeye). This fact motivated us, the Hellenic Amateur Astronomy Association(HAAA;http://www.hellas-astro.gr),topublicizethiscampaigninGreece.InHAAAourmaingoalistopromotetheamateurastronomyperformedusingthenecessarymethodologyinordertoobtainscientificallyvaluableobservationsand contributing to pro-am collaborations. Thus, the contribution to such aprojectwasconsideredasauniqueopportunitytoparticipateinandtopromoteittotheGreekamateurcommunity. ThisworkreportstheresultsofthiscampaigninGreece,includingtheaimsandtheactivitiesorganized,insection2,adescriptionofthemethodsusedandtheobservationscollected,insection3,andasmalldiscussionontheresults,insection4.

2. The campaign in Greece

2.1.Aims TheeAurcampaigninGreecewasdirectedbytheHAAAwiththehelp


of theAAVSO/Citizen Sky staff.The main goals of this campaign were to:(i) inform the Greek community about the rarity and the importance of theeAur’s eclipse, (ii)provide thenecessarymaterial forobservations forbothexperienced and first-time observers, (iii) collect all observations by Greekobservers,(iv)forwardthesetotheAAVSOdatabase,(iv)constructthelightcurveoftheeclipsealongwithanyinterestingresults.

2.2.Activities Inordertobetterpromotethecampaign,wehavecreatedthededicatedwebpage “The observational program of e Aur” (currently available inGreek athttp://www.hellas-astro.gr/article.php?id=765&topic=variables&subtopic=&lang=el) inwhichwepublished relatedmaterial.This includedanalyticalguidesonhowtoperformvisualobservations,maps,tips,newsandupdatedinformationonthesystem,andafrequentlyupdatedplotofallobservationscollected. Thispagehasalreadybeenupdatedthirteentimesanditwillcontinueasnewinformationandresultswillbecomeavailable.UpdatesweremailedtotheobserverswhohavealreadysubmittedobservationsandwerepublicizedatthetwomainforaofamateurastronomersinGreece,Astrovox(underthethread“epsilonAur”,http://www.astrovox.gr/forum/viewtopic.php?t=10578&highlight=\%C7\%ED\%DF\%EF\%F7\%EF\%F5) and AstroForum (under the thread“epsilon Aur”, http://astroforum.gr/forum/viewtopic.php?t=3862&highlight=\%C7\%ED\%DF\%EF\%F7\%EF\%F5), with almost 5,000 reads each. Atthesame time, therewasalsoa threadactive in the forum(under the thread“Greekon-goingvisualobservations”,http://www.citizensky.org/forum/greek-going-visual-observations)oftheCitizenSkyproject,whichwasinformingtheinternationalcampaignabouttheprogressinGreece. Aformalcallforobservationswasmadeduringatalkatthe6thPanhellenicConference on Amateur Astronomy held in Alexandroupolis, Greece, onSeptember26,2009(Maravelias2009),withmorethan500participants.Thetalk was also accompanied by a practical mini-workshop during the night,in which volunteers tried the visual observing technique on the system. Inaddition,twooftheregularmeetingsoftheHAAAwerededicatedtoeAur,regardingtheprogressoftheobservationsandoftheeclipsealongwithnewresultsobtained.Numerousinformaldiscussionstookplaceatthemeetingsandviathemailinglist. eAur was presented in all talks and workshops related to variable starsthattookplaceaftertheinitializationofthecampaigninMarch2009.Wetookadvantageofeveryeventtopublicizetheneedforobservationsandthecampaignitself(thatis,thePanhellenicAstropartiesof2009and2010,atAnavra-FthiotidaandMt.Parnonas,respectively,andthe“SunandVariableStarsMeeting”attheUniversityofAthensin2010).Especiallyinthecasesofworkshopsweofferedthe opportunity for hands-on experience of visual and digital observations.


AlthoughwedidnotcirculateanypressreleasesabouttheeAureclipse,there was one article, to the best of our knowledge, published in a nationalcirculation newspaper dedicated to this event (“Vima Science,” January 17,2010).TheauthorreferredtobothhistoricalandnewdataaboutthesystemanddidnotfailtorefertotheCitizenSkyprojectandtheGreekcampaign.

3. Observations

The campaign in Greece was heavily based on visual photometricobservations. However, we still experiment with other kind of observations,includingDSLRphotometry(GMwasamemberoftheDSLRDocumentationand Reduction team of the CitizenSky project (http://www.citizensky.org/teams/dslr-documentation-and-reduction,responsibletodevelopobservationalmethods and tutorials), CCD photometry (IMS was an official member ofthe International Epsilon Aur Campaign 2009 (http://www.hposoft.com/Campaign09.html)), and low-resolution spectroscopy.The observations willbe web-archived and made available through theAAVSO ftp site at ftp://ftp.aavso.org/public/datasets/gmaraj402.txt. We present each method andobservationsobtainedinthefollowingsections.

3.1.Visual Visualobservationsareallobservationsthatareobtainedusingtheeyeasaphotometer,eitherunaidedorthroughanopticalsystem(thatis,binocularsoratelescope).SinceeAurisabrightobjectthemajorityoftheobservationsweremadeusingunaidedeyeandbinoculars. The method used for visual observations is simply based on thecomparisonofthetargetstar(eAur)withtworeference(comparison)stars,usuallyhAurwith3.2V-magnitude(invisualobservationsallmagnitudesareroundedtothefirstdecimalplace),zAurwith3.8V-magnitude(actuallyit isaneclipsingbinaryof~3.75V-magnitudewithadropof~0.1duringeclipse,every2.7yearswitheclipseduration~40days,butitisconsideredas non-variable during the major part of the eAur eclipse except for theperiodNovember–December2009whenitwasineclipse—duringthattimeitwasavoidedasacomparisonstar),or58Perwith4.3V-magnitude.Bycomparingourtargetwithafainterandabrighterstar,wewereabletoplaceitbetweenthetwomagnitudes.Usuallytheerrorofthesemeasurementsisnot given, and an accuracyof a few tenthsofmagnitude is assumedwiththe most experienced observers going down to 0.1, although a subject ofcontroversy(Priceet al.2006).Insomecaseswewereabletogodownto0.05magnitudeerror,partlyduetothesmalldifferencebetweenzAurand58Per(wheneAurwasin-between)andpartly to thegrowingexperienceandconfidencewiththefield. Byapplying thismethodwewere able to collect 302observations fromtwenty-onepersons,presentedinTable1.


3.2.CCD TheCCDobservationswereperformedbyusinganATik16ICmonochromecamera,equippedwithaZenit55mmf /2.8lens,andaJohnsonVphotometricfilter with the whole setup mounted on an equatorial mount. The reductionprocedure followed is the standardone forCCDobservations: (i) create themaster-dark, themaster-bias,and themaster-flat images(usually twenty-fiveimageswerecombinedforeachmaster image), (ii)subtractmaster-darkandmaster-biasfromeachscienceimage,(iii)divideeachofthesebythemaster-flat,(iv)alignandstackimagesofeachset(usuallytensetsofthirtyscienceimageseach),(v)performphotometryusingtheMaxImDLsoftware. The comparison stars used were h Aur and z Aur. Since the latter isan eclipsing binary the V-magnitude to use was provided each week byJeffHopkins (coordinator of the InternationaleAurCampaign2009).ThereductionandthephotometrywereperformedaccordingtotheguidelinesoftheInternationalCampaign. Usingthistechniquewecollected95CCDobservations,allacquiredbyasingleobserver.DetailsarepresentedinTable2.

3.3.DSLR DSLRphotometryreferstotheuseofanormalDigitalSingle-LensReflexcamera (DSLR) or any digital photography camera which: (i) can produceimages in a RAW data format, (ii) can focus semi-manually, (iii) is able tomanually select a shutter speed/exposure timeof several seconds, (iv) has awideenoughfield-of-viewtogetavariablestarandacomparisonstarintheimage.Inordertoobtaintheimagesneeded,thecameraisusuallymountedonasimpletripodwithatypicallensof50–90mmandexposuresofsomesecondstocapturethebrightstars(Kloppenborget al.2012,inthisvolume). ThedatareductionofDSLRobservationsfollowsthatoftheCCD.Inourcasethough,biasandflatfieldswerenotavailable,soaslightlydifferentprocesswasfollowed:(i)themaster-darkwascreatedasnormal(fromdarkimages),(ii)usingthreescienceimageswecreatedthemaster-flat(mediancombineoftheimages),(ii)subtractthemaster-darkfromscienceimages,(iii)divideeachof these by the master-flat, (iv) align and stack images of each set (usuallyaroundeightimages),(v)separatestackedimagestotheirRGBBayerpattern,andkeeponlytheGreenchannel(closermatchtotheVfilterpassband),(vi)performphotometry. The DSLR Documentation and Reduction team of the Citizen Skyproject has developed standard guides (http://www.citizensky.org/content/dslr-documentation-and-reduction)forsomewidelyusedsoftwarepackageswithin theamateurastronomercommunity(iris, aip4win, maximdl) inordertopresenteasywaystoreducedataandperformphotometry.Inthisworkweusediris(freesoftware)forimagereductionandphotometry,alongwiththespreadsheetsprovidedforthispurposeattheCitizenSkysite.WeusedhAur


asacomparisonstarwhileothers(thatis,zAur,lAur,oAur,and58Per)wereusedforcolorandairmasscorrection.TwooftheDSLRobservationswereanalyzedwith theMaxImDLsoftware,wherehAurandzAur starswereusedascomparisonstars. Usingthistechniquewemanagetocollectelevenobservationsfromthreepersons.TheobserversandthesystemsusedarepresentedinTable2.

3.4.Spectra3.4.1.80-mmrefractor As low resolution spectroscopy is available to amateur astronomers, asample was obtained with a Sky Watcher 80-mm Apochromatic refractorequipped with an ATiK 16 IC camera (640×480 px) and a Baader BlazeGratingSpectroscope(207lines/mmgratingwithadispersionof1267Å/mmandwavelengthcoverage~3800–6800Å). The spectraextractionwasperformed through the rspec software.Usingthe standard libraries, anA7Vspectral type starprofilewas selected for theidentification of the Balmer lines as well as for the wavelength calibration.Fromthecalibratedspectrum,theBalmerlineswereremoved,leavingonlyafeaturelessspectrumcomposedofthecontinuumemissionofthestarandtheinstrumentalresponseofthesystem.Bydividingthisresultbytheinstrumentalresponseweobtainedthefinalnormalizedspectrum. Usingthismethodwecollectedfourspectra,obtainedbyasingleobserver(Table3).OneofthesespectraispresentedinFigure1.

3.4.2.1.3-mreflector We were also able to use the slit spectrograph mounted on the 1.3-mtelescope at Skinakas Observatory (http://skinakas.physics.uoc.gr/en/) toacquireonespectrumofeAurduringitseclipse,on30September,2010.Thetelescopeisequippedwithaslitspectrograph(1302lines/mmwithadispersionof70.44Å/mmandwavelengthcoverage~5210–7280Å)anda2000×800ISASITeCCD. Thedatareductionperformedinirafincluded:(i)biassubtraction,(ii)flat-fielding,tocorrectpixel-to-pixelvariationsacrossthechip,and(iii)wavelengthcalibration.Thefinalcorrectionwouldbe toremove thecontinuumwith thehelpofastandardstar.Sincenostandardwasobservedthatnightandnogoodone was available we decided to leave the spectrum uncorrected.Althoughpresent,thecontinuumdoesnotprohibitusfromidentifyingbasicfeaturesinthespectrum. Onlyonespectrumwasobtainedwiththissetup(Table3)andispresentedinFigure2.


4. Discussion

4.1.Statistics ThemainaimofthecampaigninGreecewastocollectalltheobservationsmadebyGreekobserversduringthe2009–2011eclipse(Figure3).Atotaloftwenty-oneindividualsmanagedtoobtain302visualobservations.Outofthetwenty-oneobservers,onlythreewerenotengagedwiththecampaignrunbytheHAAAandtheirobservationswereacquiredthroughtheAAVSOInternationalDatabase.However,themajorityoftheobservers(~86%)wereparticipantsofthiscampaign(thatis,theysubmittedtheirobservationsdirectlytoHAAA)andprovidedalmostall theobservations(93%).It is interesting topointout thatthirteenparticipants(~72%)werefirst-timersinvisualobservationsofvariablestars,butonlythreeofthemobservedmorethanacoupleoftimes.Althoughwewereexpectingalargercontribution,wehopethatthenewobserverswillcontinueobservingothervariablestars.Intotalthevastmajorityofthedata(255observations,almost84%of the total sample)camefromonly fourpersons,alreadyexperiencedobservers. Outoftheeighteenparticipantsofthecampaign,sixwerenotmembersoftheHAAA,whichmeansthatactuallytherewasanumberofpeopleoutsidetheHAAAinterestedinthecampaign.Inaddition,sevenoftheparticipantswerealreadyAAVSOobservers(thatis,theyhadanAAVSOobservercode). Althoughthecampaignwasheavilybiasedtowardsthevisualobservations(74% of the whole sample), there had been systematic work with digitalobservations(DSLR/CCD).Onlythreepeopleobservedusingdigitalsystems(twoDSLRusersandoneusingboth).Oneofour team(IMS)usedaCCDcameraaspartoftheInternationaleAurCampaign2009,producingthemajorityofthedigitalresults(almost90%ofalldigitalobservations). Spectroscopicobservationswerealsoattemptedbytwoobservers(ISMandGM),butmainlyastests.ExperienceandtimeavailabilitywaslimitedtofullyexploitthepowerfultoolofspectroscopyforeAur,buttheknowledgegainedcouldbeusedinfutureprojects.

4.2.Visualobservations InFigure4wepresentallthevisualobservationsobtained(indicatedasthe“rawdata”inthefigure).Itisobviousthatwewerecompletelysuccessfulinfollowingthe2009–2011eclipseofeAur.Thenumberofobservationsisnotsufficienttoextractsolidconclusionsbutsomeinterestingresultscanbepresented. Inordertoperformabasicreductionoftheobservationsweusedbinsof15days.Binswithfewerdaysareclosetothesamplingperiod,astheobservationswereobtainedonceperweekortendays.Binswithmoredaystendtosmoothtoomuchthelightcurve,asitisnotrealisticforthestartobeconstantinatimespanof20to30daysormore.Foreachbinthemedianvalueandthestandard


deviation(s)were calculated. In thecaseswhereonlyoneobservationwasobtained,anerrorof0.1magnitudewasassumed (corresponding to thebestcase scenario—experiencedobservers).Thenall thedatawhichwerewithinthe3×srangewerekept(indicatedasthe“reduceddata”inFigure4).Weusedthesedatatoobtainthemedianvalueanditscorrespondingerrorforeachbin(representedasthe“median”lineinthesamefigure).Byvisualinspectionofthefinalresultsomeinterestingfeaturesoftheeclipsecanbeidentified. TheV-magnitudeofthesystembeforeenteringeclipsewas~3.0.Thesmalldropof0.1magnitudeaftertheMJD55050(August6,2009)cannotidentifythebeginningoftheeclipse(duetothe0.1-magnitudeoscillationsofthesystem(Carroll1991;Hopkinset al.2008).Onlylater,withinMJD55077–55097,wehaveaclearerindicationoftheingress,whichcouldbeplacedaroundtheMJD55087(August12,2009),withanerrorequivalenttothebinsize(thatis,±15days).Thedateiswithinthepredictedrangeofdates(Hopkinset al.2008). OnlyafterMJD55218(February2,2010),eAurseemstohavereacheditsfaintstate(totality)atmagnitude~3.8,losingalmost0.8magnitudein131±15days,inagreementwiththevaluesof137daysforthe1982–1984eclipseand135daysforthe1955–1957eclipse(Carrollet al.1991).TherewasasmalltrendofbrighteningafterMJD55261(March5,2010),whichcouldtemptustocreditittothemid-eclipsebrightening.However,sincetheerrorsarelarge,thebrighteningisnotstatisticallysignificant.Moreover,duringthisperiodeAurwasgettingloweronthehorizonandafterpassingbehindtheSun(June2010),itwasagainlowonthehorizon,whentheobservationswereresumed.Thispositiondefinitelyaffectedtheobservationsduetotheairmass. AftertheMJD55376(June28,2010)wenoticeascatterofvaluesaroundmagnitude ~3.7–3.75. There can be no estimation when the system passedfromthethirdcontact(startofengress)duetothedatascatter.OnlyafterMJD55797(August23,2011)wecanacceptthateAurwastotallyoutoftheeclipsewithaV-magnitude~3.1.Usingthepreviouslyestimateddateofingress(MJD55087)wecalculatethedurationofthe2009–2011eclipsetobe710±21days,whichisactuallywithin2–3sfromthepreviouseclipsedurations,647daysin1982–1984and670daysin1955–1957(althoughthereisatrendfordecreasingduration(Carrollet al.1991).

4.3.CCDandDSLRobservations We present the digital data (DSLR and CCD observations) in Figure 5.AllobservationswereobtainedwithinMJD55128–55545(October23,2009–December14,2010),wheneAurwasalreadyineclipse,withthemajorityofthedataobtainedduringtotality.Thus,therearenoadditionaldatatoallowforthedeterminationofingressorengress.Nevertheless,weobservemodulationsof~0.07magnitude,inagreementwithpreviousresults(Hopkinset al.2008;Carrollet al.1991).Thefaintestvalue,withinerrors,thateAurreachedwasmagnitude 3.789 ± 0.003. Moreover, the oscillations displayed in Figure5,


withmaximanearMJD55285,55400,and55470,probablyreflectsthe67-and123-dayperiodsidentifiedbyKim(2008). AfterMJD55305(April18,2010)anduptoMJD55335(May18,2010),thesystemseemstohavebrightened,witharesultingchangeinV-magnitudeof0.13magnitude.It isinterestingtoobservethatthistimeperiodcoincideswiththepossibletrendobservedinthevisualdata(seeFigure4).Although,theerrorsarelargeinvisualobservations,preventingusfromdefinitelyidentifyingthebrightening,theCCDobservationsaremoreaccurateandtheyarecorrectedfortheairmass.Thus,thistrendintheCCDobservationsismorerealisticandcouldbeattributedtothemid-eclipsebrightening.

4.4.Spectra As there have been only a few tests with spectroscopy, we present thebestspectraobtainedinFigures1(spcA)and2(spcB).Theobservationswereobtained during the eclipse of eAur and, as such, its spectrum would be acompositeofthemainstarandthedisk.Thus,itisoutofthescopeofthisworktopresentaclassificationoranyspectralresultsregardingwiththenatureoftheobjects,butrathertopresentasampleoftheobservationsperformedandthelinesidentified. Thereisanoverlapofthetwospectraintherange5200–6700Å,wherethemostprominentfeaturesaretheNaIDoubletll5890,5896lines(characteristicfeatureofF-toM-typestars(Monteset al.1999))andtheHal6563line.Bothoftheselinesarevariableduringtheeclipse,revealingpropertiesforboththediskandtheprimarystar(Barsonyet al.1986;Chadimaet al.2011).OutsidethisregioninspcAallBalmerlinesareevidentwithsomeadditionalfeaturesaroundll4040, 4480, and 5050 but we were unable to resolve which linestheyare(thoughthel4480linecouldbetheMgIIlineatl4481Å).However,inspcBwewereabletoidentifynumerousmetalliclines.ThemostabundantmetalisironwithlinessuchasFeIIll5235,5274,5316,5363,6148,6238,and6247 lines and FeIll5226,5325,5657, and 5780 lines.Also present are theNiIIIl5534lineandtheSiIIll6347,6371lines(Chadimaet al.2011).Inthiscase,theNaIDoubletisalsonicelyresolvedtoitstwoseparateabsorptionlines(ll5890,5896,seeinsetgraphinFigure2).

5. Conclusions

The current work is a report of the results obtained from the Greekcampaigndedicatedtotheobservationofthe2009–2011eclipseofeAur.WehavebeensuccessfulininformingtheGreekamateurastronomicalcommunityabout the eclipse and its importance. Furthermore, we publicized the eventand the appropriate material for both experienced and first-time observers,byusing internet resources (dedicatedwebpage, threads inwell-knownfora)andtalks/workshopsatmajorastronomicalevents.Wemanagedtocollect413


observations (302visualestimates,95CCD,and11DSLRmeasurements,5low-resolutionspectra)from21Greekindividuals,whichhavebeensubmittedtotheAAVSOInternationalDatabase. Wewereable toconstruct the lightcurveof theeclipseand,evenundersome limitations of the data, to extract some interesting results. By visualexaminationofthelightcurvewenoticedthesystem’sV-magnitudedroppedfrom~3.0to~3.8,in131±21days,inagreementwithCarrollet al.(1991).WeestimatedtheingressdatearoundtheMJD55087±15days(August12,2009),withinthepredictedrangeofdates,andtheexitoftheeclipseaftertheMJD55797±15days(August23,2011).Thedurationofthe2009–2011eclipsewasfoundtobe710±21days,withintheerrormarginsofpreviouseclipses(Carrollet al.1991).Althoughwecannotconfirmthemid-eclipsebrighteningbythevisualobservations,theCCD/DSLRdatapresentedaratherpossibleindication.Moreover, 0.07-magnitude oscillations were present in the CCD/DSLR datainagreementwithpreviousobservations(Hopkinset al.2008;Kim2008).Inaddition,wepresentedourfirstattemptsatspectroscopicobservationsofeAur,whichresultedintheidentificationoftheNaIDoubletll5890,5896lines,theSiIIll6347,6371lines,andnumerousFeIandFeIIlines(Barsonyet al.1986;Chadimaet al.2011).

6. Acknowledgements

The authors are grateful to the observers: Athanasios Douvris, NikosFlemotomos,DimitrisGkionis,PanagiotisKottaridis,KrikisManolis,DimitrisManousos, Eleni Maraki, Serafim Ntovolos, Kostas Dimitris Panourakis,Paschos, Giorgos Stefanopoulos, Vasilis Takoudis,Andromachi Tsouloucha,Lefteris Vakalopoulos, George Vithoulkas, Giorgos Voutiras, and OrfeasVoutiras. TheauthorswouldliketothanktheAAVSOanditsCitizenSkyproject,especiallyAaronPriceandBrianKloppenborg.GMwouldliketoacknowledgethehelpofPabloReigregardingspectroscopyobtainedatSkinakasObservatoryand thevaluablediscussionswithThodorisBitsakisandPaoloBonfini. IMSacknowledgesthehelpofJeffHopkinsandRobinLeadbeater. Also, we acknowledge the supporting communities of the free/opensoftwares iris, python/matplotlib, and iraf, which have been used for thiswork.ThisresearchhasmadeuseofNASA’sAstrophysicsDataSystem.

References

Barsony,M.,Lutz,B.L.,andMould,J.R.1986,Publ. Astron. Soc. Pacific,98,637.Carroll, S. M., Guinan, E. F., McCook, G. P., and Donahue, R. A. 1991,

Astrophys. J.,367,278.Chadima,P.,et al.2011,Astron. Astrophys.,530A,146.


Guinan,E.F.,andDeWarf,E.2002,inExotic Stars as Challenges to Evolution,eds. C.A. Tout and W. Van Hamme,ASP Conf. Ser. 279,Astron. Soc.Pacific,SanFrancisco,121.

Hoard,D.W.,Howell,S.B.,andStencel,R.E.2010,Astrophys. J.,714,549.Hopkins, J. L., Schanne, L., and Stencel, R. E. 2008, in The Society for

Astronomical Sciences 27th Annual Symposium on Telescope Science, Held May 20-22, 2008 at Big Bear Lake, CA,SocietyforAstronomicalSciences,RanchoCucamonga,CA,67.

Kim,H.2008,J. Astron. Space Sci.,25,1.Kloppenborg,B.,Pieri,R.,Eggenstein,H.-B.,Maravelias,G.,andPearson,T.

2012,J. Amer. Assoc. Var. Star Obs.,40,815.Kloppenborg,B.,et al.2010,Nature,464,870.Maravelias, G. 2009, In Proceedings of the 6th Panhellenic Conference on

Amateur Astronomy, Alexandroupolis, Greece, 25–27 September 2009,143(inGreek).

Montes,D.,Ramsey,L.W.,andWelty,A.D.1999,Astrophys. J., Suppl. Ser.,123,283.

Price,A.,Foster,G.,Skiff,B.,andHenden,A.2006,Bull. Amer. Astron. Soc.,38,1126.

Stencel,R.E.1985,in1982–1984 Eclipse of Epsilon Aurigae ,ed.R.E.Stencel,NASAConf.Publ.2384,NASA,Washington,D.C.,v.


Table1.VisualobservationsobtainedbyGreekobserversduringthe2009–2011eclipseofeAur.

Name Number of Participant1 HAAA AAVSO Observations Member2 Code3

Douvris,Athanasios 1 yes no DXA Flemotomos,Nikos 1 yes no — Georgalas,Byronas 1 yes yes — Gkionis,Dimitris 5 yes yes — Kardasis,Manos 44 yes yes KMO Kottaridis,Panagiotis 5 yes yes KPAA Krikis,Manolis 1 yes no — Manousos,Dimitris 4 yes no MUQ Maraki,Eleni 1 yes no — Maravelias,Grigoris 64 yes yes MGK Ntovolos,Serafim 1 yes yes — Panourakis,Kostas 1 no no PKO Paschos,Dimitris 1 no no PDIA Stefanopoulos,Giorgos 41 yes yes STF Strikis,Iakovos-Marios 106 yes yes SIAK Takoudis,Vasilis 1 yes yes — Tsouloucha,Andromachi 2 yes no — Vakalopoulos,Lefteris 1 yes yes — Vithoulkas,George 19 no no VGK Voutiras,Giorgos 1 yes yes — Voutiras,Orfeas 1 yes yes —

Totals(persons/observations) 21 302 18 12 10

1 Defined as an observer who submitted his/her observations directly to the HAAA (in “no” cases the data were retrieved from the AAVSO International Database). 2 Member of the Hellenic Amateur Astronomy Association (HAAA). 3 Observer who submits his/her observations to the AAVSO has a unique observer code—this is given when applicable.


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Figure1.Low-resolutionspectrumofeAurobtainedonAugust27,2010.ASkyWatcher80-mmApochromaticrefractorwasusedequippedwithanATiK16 IC (mono) and a Baader Blaze grating (see section 3.4.1). CharacteristicBalmerlinesareshownalongwiththeNaIDoubletlines.SpectrumobtainedbyIMS,reducedbyRobinLeadbeater.

Figure2.Low-resolutionspectrumofeAurobtainedonSeptember30,2010.Skinakas’ 1.3-m telescope was used, equipped with an ISA SITe and a slitspectrograph(seesection3.4.2).TheHaandNaIDoubletlinesareprominentalongwithaseriesofFeIandFeIIlines,andSiIIlines.SpectrumobtainedbyGMwiththehelpofPabloReig,andreducedbyMK.


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Figure5.Plotofthedigital(DSLRidentifiedastriangles,andCCDidentifiedas crosses) observationsduring the2009–2011 eclipseofeAur (see section4.3fordetails).TheDSLRpointjustbeforeApril1st,2010,isapoorresultprobablyduetothepresenceofthinclouds.

Figure4.Plotofvisualobservationsalongwiththemedianvaluesofthebinneddata(15days).Fromtheinitialdata(indicatedas“rawdata”)valuesoutsidethe3×swereremovedandwebinnedtheremainingones(indicatedas“reduceddata”)providingthemedianvalueanditscorrespondingstandarddeviations(indicatedas“medianline”).Interestingresultsarepresentedinsection4.2.

Melillo, JAAVSO Volume 40, 2012 695

Photoelectric Photometry of e Aurigae During the 2009–2011 Eclipse Season

Frank J. MelilloHoltsville Observatory, 14 Glen-Hollow Dr, E-16, Holtsville, NY 11742; [email protected]

Received February 13, 2012; revised March 1, 2012; accepted March 1, 2012

Abstract A total of 100 V-band photometric observations were made atHoltsvilleObservatoryforthe2009–2011eclipseofeAurigae.Alightcurvehasbeenplottedusingdatafromtheseobservationswhichcoversthephasesbefore, during, and after the eclipse. The light curve shows precise timingduringthefirst,second,third,andfourthcontacts,whichmarkimportantpartsoftheeclipse.ThemagnitudesanddurationoftheeclipseinthephotometricVbandarediscussed.

1. Introduction

e Aurigae is different from other binary star systems. It has been amysteriousstartoussince1821whenitwasfirstnoticedthatitwasavariable,butitwasnotwellknownuntiltheearly1900s.Thisstaristhelongestperiodeclipsingbinaryeverstudied.What’ssomysteriousabouteAuristhatwedonotknowmuchaboutitseclipsingobject.Eventhoughtheeclipsingobjecthasbeenwellidentifiedasexisting,itisstillunclearwhatitismadeof.Withits27.1-yearperiod,it isasloweclipselastingatotalof1.75years.Regardlessofwhatequipmentyouusetostudythisbinarysystem,thereisnoclearclueabout theeclipsingobject.Usingphotometry, spectroscopy,polarimetry,andinterferometry,wearebeginningtogetanindicationofitsnature.Duringthetimeoftheeclipse,eAurdimsabout0.8magnitudeandthenreturnstoanormalbrightness. What isknownabout thisbinarystar system is that theeclipsingbody’sorbitisinourlineofsight.Every27.1years,eAurundergoesaneclipsewhichmeanstheunknownsecondaryobjectpassesinfrontofastarasseenfromtheEarth,causingthelighttodim(Hopkinset al. 2006).TheeAursystemissostrangethatitisunique.Withsuchararebinarystarsystem,itisdifficulttostudytheeclipseevery27.1years.SomethingisorbitingeAur,butwhatisit? eAurisknowntobeaF0-typestaranditisahighlyluminoussupergiantatVmagnitude3.00.TheeclipsingobjectorbitingthisF0-typestardoesn’texhibitanyspectrumofitsownbutitismostlikelytobeahiddenB-typestar.Thediskmustbedarkbuthavetransparentregions.Butduringtheeclipse,stillitisthickenoughtoobscuresomeofthelightfromtheF0star.Thevisuallightcandimabout0.8magnitudeeventhoughthespectrumdoesnotchange.Also,theF0

Melillo, JAAVSO Volume 40, 2012696

staritselfisavariableanditisperhapsasemiregulartype.Itisapulsatingstaroutsideoftheeclipsewithaperiodof60to65days.Theamplitudecanchangeasmuchas0.15magnitudeinadditiontotheeclipse. eAurhasbeenstudiedsubstantiallyevery27.1years.The1982–1984eclipsewas observed by many amateur astronomers, by ground-based professionalobservatories, and from space. No matter what data were collected, still itwasacompletelymysteriousstar.Thereissomuchinterestinthisbinarythatall observers are trying to squeeze out as much detail as possible about thesecondary.Whatwereallyseeisonlythelightoftheprimarystar. ThelongawaitedeAur2009–2011eclipseisfinallyover.Priorto2009,many organizations and observing campaigns were formed (Hopkins et al. 2008).Thisauthorisparticipatinginoneorganization,whichisrunbyJeffreyHopkinsofPhoenix,Arizona.During the2009–2011eclipse,manyamateurastronomerswereequippedwiththemostadvancedtechnology,especiallyinspectroscopy, which plays an important role for eAur where the secondarycan be detected at certain wavelengths. Also, the Center for High AngularResolutionAstronomy(CHARA)operatesaninterferometeronMountWilsoninCalifornia(Kloppenborget al.2010).Withup tosix telescopescombinedtogether in infrared light, they have successfully imaged eAur. They wereable to detect an elongated object partially obscure the primary disk.The eAureclipseof1982–1984wassuccessfulbut leftusmanyquestions for the2009–2011season.Hopefullymanyamateurandprofessionalastronomerscanshednewlightonthesecondarythistime.ThisauthorcarriedoutphotoelectricphotometryinVlightduringthe2009–2011eclipse,anditisdescribedhere.

2. Method

PhotoelectricphotometrywastheonlymethodthisauthorusedtomonitortheentireeclipseofeAur.TheobservationsprovidedanexcellentcoverageinVband.ItisaJohnson-typefilterwithapeakspectralresponseat5400nm.The readings were taken photometrically using a SSP3 OPTEC photocountingphotometercoupledonaCelestron8-inchf /10telescope.lAurwasthecomparisonstaratVmagnitude4.71.Itislocatedjustfourdegreeseast-southeastofeAuranditwasanexcellentchoicetocompareitsbrightnessandtominimizetheatmosphericcoefficientduringthe2009–2011eclipseseason. Foreachset,fourreadingsweretakenattenseconds’integrationtimeforeAur,skyreadings,andthenthecomparisonstar,lAur.Thisauthorsometimesmonitored three to four sets, dependingon theweather condition and time.Once the observing night was over, the readings could be calculated. ThephotometricreadingsofeAur, thesky,andlAurwereaveraged.Then, thesky was subtracted from both stars’ readings. That left the ratio brightnessbetweeneAurandlAur.Oncetheratiowascalculated,eAur’sbrightnesscouldbedeterminedwiththeknownmagnitudeoflAur.Also,theStandard


Deviation(SD)wascalculatedtoanalyzehowmucherrorwasinthereadings.Mostofthetime,theerroramountwasfrom0.012magnitudetoasmuchas0.0427whenallthereadingswerecalculated.Thealtitudewasalsocalculatedto determine the air mass during the time of the observations. During theobservingrun, thehigher thestars, thebetterchanceofgettingtheaccuratereadingsfromthephotometer. Many factors had to be also considered: seeing conditions, the winds,periodicclockdriveerror,polaralignment,andthestabilityofthephotometer,whichcanallaffectthereadings.Duringmostnights,theseeingconditionwasaboveaveragewithnowinds,andtheperiodicclockdriveerrorwasnoticeableattimes.Beingthataportableobservatorywasused,thepolaraxiswasalignedascloseaspossibletothecelestialnorthpole.Therefore,inspiteofthesmalldrift,thestarstillstayedinsidethereticlecircleduringthelengthoftime.FortheSSP-3OPTECphotometer itself, theunitwas turnedonat leastanhourbeforethestartofthefirstcounts.This“warmup”routinestayedonuntilthephotometer dark count was stable enough for accurate readings. In fact, thecoldertheoutsideairtemperaturewas,themoretimethephotometerneededtowarmup.Theunitwasrunningona9-voltbatterytoavoidthepowercordtangle-upduringthenight’srun.Inthephotoelectricphotometrymethod,theaccuracy can be little as 0.01 magnitude.This author’s readings were closeenoughtogeneratetheshapeofthelightcurve(seeFigure1andTable1).

3. Observations

eAurislocatedintheconstellationAurigaeasathirdmagnitudeobjectandpassesnearlyoverheadmostevenings,asseenfromtheHoltsvilleObservatory.AllphotoelectricphotometryresultsweretakenfromHoltsvilleObservatory,locatedunderamoderatelylight-pollutedskyfiftymileseastofNewYorkCity.eAuriseasilyvisibletothenaked-eyeanditisoneofthethreestarsformingtheasterism“TheKids,”nearaAur(Capella). ThisauthorwasgearingupforthefirsteclipseoftheMillennuim.Priortothestartoftheeclipse,thefirstcontactwaspredictedtooccurinAugust2009(Hopkins et al. 2009).The observations commenced on December 3, 2008,during the 2008–2009 observing season to develop a baseline for the lightcurve.Thephotometricreadingsweretakennightly,weatherpermitting,untilthestarreachedaconjunctionwiththesuninJune2009.Withinthisperiod,eAurwasshowingaslightvariationaveragingVmagnitude3.00out-of-eclipse(OOE).Thevariationhadnothingtodowiththeeclipsingobject.eAuritselfisavariableandperhapsasemiregulartypewithamplitudeof0.10magnitude.ThelastreadingsoftheobservingseasoninVbandshowednoindicationoftheupcomingeclipse. After the solar conjunction, the observation resumed for the 2009–2010observingseason.Thefirst readingwasonAugust14,2009, in the


morningsky.Even though theexact startof theeclipsewaspredicted tobeonAugust6,2009,everything lookednormal.After severalweeks, itgotveryinteresting.Sincethestartofthenewobservingseason,eAurhaddimmedconsiderably.Thisauthordidn’tknowwhetherornotthiswasduetoeAur’svariationitselforthestartoftheeclipse.AseAurcontinuedtodim, thepartialeclipsehadactuallybegun,but itwasn’tconfirmeduntilaftermid-Septemberwhenthemagnitudedroppedbelow3.15V. TheexcitementbuiltupaseAur’sbrightnesscontinuedtofall.ThisauthortookphotometricreadingsinVbandonanaverageoftwonightsperweek.Atcertainpointsofthedecliningphase,eAur’sbrightnessreductionsloweddownabit.Thiswasduetothevariationofthestaritself.Itformedasomewhatwavypatternasitcontinuedtodim. Atthispartofthedecliningstage,theauthorwasgettingreadyforthesecondcontact.Itwasn’tuntiltheendofDecember2009whenthebrightnessdeclinesloweddownalotat3.70V.ItstillshowedaslightdimminguntillateFebruary2010when the lightcurve reached rock-bottomat3.78V—but thiswasnotnecessarilythesecondcontact.WhileeAuritselfvariedwithin0.10magnitudethewholetime,thismighthaveinterferedwiththeactualtimeofthesecondcontact,whichshouldbethebeginningofthetotality.ThesecondcontactwaspredictedonDecember19,2009,anditlookedlikeitwasrightonschedule,buttheOOEvariabilitycausedthelightcurvetodimevenfurther.Afterthesecondcontact,eAurshowedasmallvariationevenintotality.Thelightcurvecouldbeeasilyidentifiedasasemiregulartypewitha65-dayperiod. Hereistheinterestingpart:eAurisknowntoshowasurgeofbrightnessasitnearstomid-totality,whichmaycauseperhapsasmallgapinthemiddleoftheeclipsingbodytoallowtheF0startoshinethrough.Thismysteryhasnot been explained yet, but hopefully it can be solved this time. The mid-totalitywasscheduledtohappenbyearlyAugust2010.ThisauthortriedtotakereadingsasmuchaspossiblewhileeAurwasapproachingsolarconjunction,but,unfortunately,thereadingsweretakenatlowaltitudeinthenorthwestaftersunset.The accuracy of the photometric measurement was not as great, butanyattempttotakereadingswasworthwhile.Accordingtothelasttwonightsin May 2010, this author may have caught a surge of brightness to 3.55V.Thephotometricresultsmaynotbeenprovenyetbecausetheauthordidnotknowwhetherthiswascausedbyatmosphericturbulencefromthelowaltitude,eAur’svariationitself,ortheF0starshiningthroughthegap.eAurwasnotinagoodpositiontotakefurtherreadingsanditwentthroughthesolarconjunctioninJune2010. The2010–2011observingseasonbeganwheneAurwasjustpastthemid-eclipsestage.TheobservationsresumedonAugust13,2010,earlyinthemorningsky.Therewasnosurgeofbrightnessatmid-eclipsethatwasexpectedjustshortlybeforethesolarconjunction.Atthistime,theexpectedsurgeofbrightnessmayormaynothaveoccurredatexactlymid-eclipse.Thisisyettobedetermined.


ThebrightnessofeAurvariedwithin0.10magnitudethroughoutthewholesecondhalf of the eclipse,with themagnitude averaging at 3.71V.Even attotality,eAurclearlydemonstrateda65-dayvariationunrelatedtotheeclipsingbody.Thestarwasmonitoredonanaverageofonceperweek,andtheauthorpreparedforthethirdcontact,whichwaspredictedforMarch19,2011.Duringthat month, the star’s brightness became a little strange. According to theirregular65-daypattern,eAurwas expected toget a littlebrighter. Instead,itwentoff trackabit.Asthis time,wedon’tknowif thiswasrelatedtotheeclipsingbodyortheresultofthestar’sirregular-typebehavior.AfterMarch19,2011,thebrightnessbegantorisequiterapidly,whichindicatedthethirdcontacthadpassed.Thetotaleclipsewasoverandthiswasthebeginningofthepartialphase.Ithadrisenatafasterpacethanduringthedecliningstage.The fourthcontactwas scheduled forMay19,2011.Earlier thatmonth, thebrightnessleveledoffat3.25V.Again,thiscouldbeeAur’svariationitself,butatthesametime,thephotometricreadingsweregettingdifficulttoobtainduetotheloweraltitudeinthenorthwest.Thefourthcontact,whichmarkstheendofthepartialphase,wasprobablynotcaught.InlateMay2011,eAurwasapproachingsolarconjunctionandthereforenomorereadingsweretaken. More observations of e Aur began in September 2011, after solarconjunction. Even though the eclipse ended after the fourth contact aroundlateMayorJune,thisauthorcontinuedtomonitorthisstarjusttoconfirmthattheeclipsewasover.Thestarreturnedtoanormalbrightnessatanaverageof3.00V,justasbeforetheeclipse.AftermonitoringtheentireeclipseofeAur,thephotometricobservationsceasedaftertwoyearsandninemonths.

4. Conclusion

OnlytheVbandatapeakspectralresponse5400nmwasusedtodeterminetheaccurateshapeofthelightcurve.Theresultmaybesimilartothe1982–1984 eclipse but a closer look might detect some differences, especially inspectroscopy. However, the mid-eclipse brightening is still a mystery and itwasn’twellobservedduetothetimeofthesolarconjunction.Itisstillprematuretodrawanyconclusionwhetherthemid-eclipsebrightnesstookplaceinthiscycle. Thecontactpointsneedfurtheranalysisinordertodrawanyconclusion.It isquitedifficult toobtain thedataof thecontact timejustbyoneperson.Therearegapsbetweentheobservationsandprobablytheactualcontacttimemaybemissedevenbyoneday.Buttheauthor’slightcurvewasconstructed(see Figure 1) and we see two different types of variations.WhileeAur isa semiregular typevariable star, the65-day cycle0.10magnitude is clearlyseeninthelightcurve.Secondly,theeclipsingobjectofa27.1-yearperiodisobvious—seen at 0.70 magnitude amplitude.With 100 data points, one canshowthattheeclipsetookplacebutnotclearlymarkthecontactpoints.The


actual timeof thecontactpointsmaybeconfusedbyeAur’s65-daycycle,andthe0.10-magnitudevariationisenoughtoburytheactualcontacttimes.Using only the author’s data, it would be premature to draw more specificconclusionsaboutthecontacttimes.Datafromotherobserversmayfillinthegapsandthereforethecontacttimesmaybedetermined.Also,theresultsmaybecomparedwitheclipsesofthepasttoseewhetherthereisanysignificantdifference. While the photometric data gathered by participants is muchmoresophisticatedthanforthepasteclipses,thetrulynewtypeofdataisthespectroscopy.With today’sadvanced technology, thiscollectivephotometricand spectroscopic data set is the best ever obtained. The eAur 2009–2011eclipse isbehindusand the resultswillbestudiedformanyyears tocome.Still,therewillbemorequestionsthananswers.Hopefully,wewillhavemoreanswersbythenexteclipsein2036–2038.

References

Hopkins.J.L.,et al.2006,“Long-PeriodEclipsingBinarySystemeAurEclipseCampaign,”PresentedattheMay2006SocietyforAstronomicalSciencesSymposium,BigBear,California.

Hopkins J. L., et al. 2008, “Gearing Up for e Aur’s First Eclipse of theMillennium,”Proceedingsforthe27thAnnualConferenceoftheSocietyforAstronomicalSciences.

Hopkins,J.L.,et al.“2009:Theeclipsebegins—ObservingCampaignStatus,”PresentedattheSocietyforAstronomicalSciencesSymposium.

Kloppenborg,B.,et al.2010,Nature,464,870.


2008Dec03 2454803.73611 2.97 0.02569 2008Dec13 2454813.7222 3.04 0.01987 2008Dec26 2454826.6875 2.99 0.02654 2009Jan04 2454835.70833 2.98 0.02987 2009Jan22 2454853.59722 2.98 0.02226 2009Jan30 2454861.70833 2.99 0.02321 2009Feb09 2454871.625 3.02 0.00754 2009Feb21 2454883.70833 3.07 0.01987 2009Mar18 2454908.64583 3.08 0.01402 2009Apr06 2454927.58333 3.07 0.01954 2009Apr13 2454934.61806 3.0 0.01563 2009May21 2454972.5625 2.92 0.04598 2009Aug15 2455058+ 2.97 0.01548 2009Aug23 2455066.79167 3.01 0.02112 2009Aug31 2455074.76389 3.02 0.01548 2009Sep06 2455080.76042 3.04 0.01289 2009Sep14 2455088.73611 3.1 0.01985 2009Sep18 2455092.73611 3.13 0.00874 2009Sep20 2455094.75 3.16 0.01482 2009Sep26 2455100.72625 3.2 0.01365 2009Sep28 2455102.72625 3.21 0.01759 2009Oct02 2455106.71139 3.25 0.02236 2009Oct06 2455110.69819 3.28 0.02 2009Oct12 2455116.71146 3.32 0.01913 2009Oct20 2455124.66993 3.33 0.01775 2009Oct26 2455130.69507 3.37 0.0188 2009Oct30 2455134.6559 3.38 0.01999 2009Nov04 2455139.70882 3.4 0.02198 2009Nov09 2455144.65146 3.41 0.01559 2009Nov18 2455153.71319 3.44 0.02646 2009Nov21 2455156.70903 3.44 0.02429 2009Nov29 2455164.75347 3.48 0.03114 2009Dec04 2455169.71424 3.53 0.01975 2009Dec11 2455176.71243 3.57 0.0204 2009Dec17 2455182.63146 3.62 0.0173 2009Dec22 2455187.72181 3.66 0.0124 2009Dec28 2455193.6325 3.67 0.01215 2010Jan11 2455207.63194 3.68 0.01614 2010Jan15 2455211.52264 3.68 0.02811

Table1.DifferentialphotometryofeAurigae. UT Date JD V Filter Magnitude Standard Deviation

table continued on following pages


2010Jan19 2455215.52937 3.68 0.0363 2010Jan23 2455219.75847 3.69 0.02937 2010Jan28 2455224.51042 3.7 0.01443 2010Feb01 2455228.70486 3.7 0.02712 2010Feb08 2455235.62917 3.72 0.01923 2010Feb13 2455240.71597 3.73 0.02232 2010Feb20 2455247.71347 3.77 0.01564 2010Mar03 2455256.63194 3.76 0.02179 2010Mar07 2455262.52986 3.76 0.0174 2010Mar17 2455272.64306 3.74 0.01712 2010Mar25 2455280.64938 3.73 0.02301 2010Apr02 2455288.65486 3.74 0.02851 2010Apr15 2455301.56736 3.78 0.01706 2010Apr20 2455306.62931 3.76 0.02374 2010Apr24 2455310.62778 3.76 0.03999 2010Apr29 2455315.60361 3.76 0.04549 2010May06 2455322.56451 3.78 0.02002 2010May16 2455332.5711 3.71 0.03709 2010May17 2455333.57111 3.69 0.03997 2010May27 2455343.55278 3.56 0.02828 2010Aug14 2455422.82389 3.68 0.01155 2010Aug21 2455429.81597 3.68 0.02243 2010Aug28 2455436.79354 3.7 0.01768 2010Sep05 2455444.77292 3.7 0.02137 2010Sep15 2455454.73403 3.67 0.02348 2010Sep21 2455460.73056 3.65 0.03312 2010Oct03 2455472.72431 3.65 0.01199 2010Oct09 2455478.71007 3.68 0.03198 2010Oct18 2455487.65347 3.67 0.0159 2010Oct23 2455492.68597 3.7 0.0128 2010Nov01 2455501.64625 3.73 0.02182 2010Nov06 2455506.68056 3.73 0.02324 2010Nov13 2455513.72514 3.75 0.0194 2010Nov20 2455520.72222 3.74 0.01928 2010Nov29 2455529.64236 3.72 0.03263 2010Dec08 2455538.71181 3.7 0.01633 2010Dec18 2455548.71042 3.68 0.01852 2010Dec30 2455560.63889 3.71 0.03079 2011Jan06 2455567.52431 3.75 0.03577

Table1.DifferentialphotometryofeAurigae,cont. UT Date JD V Filter Magnitude Standard Deviation

table continued on next page


2011Jan14 2455575.52694 3.75 0.01603 2011Jan31 2455592.63472 3.74 0.02098 2011Feb04 2455596.52847 3.76 0.02623 2011Feb11 2455603.53104 3.75 0.01365 2011Feb23 2455615.52639 3.76 0.02029 2011Mar02 2455622.69104 3.73 0.03067 2011Mar09 2455629.69313 3.71 0.03032 2011Mar14 2455634.59722 3.67 0.02517 2011Mar20 2455640.69722 3.59 0.04129 2011Mar25 2455645.69604 3.55 0.02363 2011Mar29 2455649.70271 3.5 0.03054 2011Apr06 2455657.65646 3.42 0.02266 2011Apr22 2455673.65542 3.31 0.03364 2011May01 2455682.58889 3.35 0.3777 2011May06 2455687.57313 3.32 0.03628 2011May11 2455692.57201 3.3 0.01258 2011May12 2455693.56646 3.26 0.02463 2011May26 2455707.55549 3.3 0.05566

Table1.DifferentialphotometryofeAurigae,cont. UT Date JD V Filter Magnitude Standard Deviation

Figure1.LightcurveofeAur,2008–2011.VmagnitudeiswithrespecttolAurcomparisonstaratVmagnitude4.71.

Rutherford, JAAVSO Volume 40, 2012704

Small Telescope Infrared Photometry of the e Aurigae Eclipse

Thomas P. Rutherford201 Clear Branch Circle, Blountville, TN 37617; [email protected]

Received May 15, 2012; revised June 18, 2012; accepted June 18, 2012

Abstract Near-infraredphotometryofeAurigae,intheH-andJ-bands,wasundertaken during the 2009–2011 eclipse using telescopes of moderate size(8-inchand14-inchdiameter).InstrumentsofthissizesuccessfullycollectedscientificdataintheH-andJ-bands.ObservationsweremadefromthecampusofEastTennesseeStateUniversity(ETSU),JohnsonCity,Tennessee,thecampusofKingCollege,Bristol,Tennessee,andfromtheauthor’shome.Signal/Noiseratiosofapproximately45wereobtainedduring timesofmaximumeclipse.HigherS/Nratioscouldhavebeenobtainedbyextendingthelengthoftimeontarget.S/Nratiosofalmost100wereobtainedoutsideofeclipse.Theinfraredlightcurvesproducedcloselyparallelthelightcurveinthevisualrange(V),beingabout0.5magnitudebrighterinHand0.7magnitudebrighterinJ.Theeclipsewaseasilydetectedandfollowedthroughoutitsduration.TherateofingresswasshallowerthantherateofegressinboththeH-andJ-bands.Thebackgroundvariationsoftheprimarystarwerereadilydetected.1. Introduction

ThevariablestareAurhasbeenofinteresttoastronomersforalmosttwocenturiesduetoitslongperiod(27.1years)andthelongduration(approximatelytwoyears)ofitseclipses.Withsuchalongeclipse,theoccultingobjectcannotbe another star, but must be some other type of object.The exact nature oftheeclipsingobjecthasbeenamystery,althoughmoreinformationbecomesavailableeach timeaneclipseoccurs.This isdue tobothan increase in thenumberofobserversandalsocollectionofdatainadditionalwavelengthsnotutilizedinpreviouseclipses.Thecurrentmodeloftheoccultingobjectisthatofalarge,cooldiskwhichcontainsacentralB-typestar(Stencel2011). Infraredphotometryhas,untilrecently,beentheprovinceofprofessionalastronomers,usinglargetelescopes,sophisticatedinfrareddetectors,andhigh-altitudeobserving sites.UKIRT,SOFIA, IRTF, andSpitzer are a fewof theprofessionalinstrumentsthatcometomind.Itisnowpossiblefortheaveragevariablestarobserver,usingacommontelescopeofmodestsize,toworkinthenear-infraredpartoftheelectromagneticspectrumandtoproducehighquality,scientificallyusefulresults.TherecenteclipseofeAurprovidedanexcellentopportunitytodemonstratethesecapabilities;duringpreviouseclipses,infraredstudieswere restricted toprofessionalobservatories since amateurobserversdidnothavethecapabilty.

Rutherford, JAAVSO Volume 40, 2012 705

Therearenumerousadvantages(andsomedisadvantages)fortheobserverwho works in the near-infrared when compared to visual-band photometry(Templeton2011a):

1) Theskyisverydarkintheinfrared;thereislittleinfraredlightpollution.Aninfraredobservercanworkunderconditionsthatwouldmakevisual-bandphotometrydifficult.

2) Atmospheric extinction,while present, is lowcompared to thevisualwavelengths.Astheeclipseneareditsend,somedatawerecollectedattheveryhighairmassof5;thishighairmassdidcauseanincreaseinnoise,buttheS/Nratiowasstilladequate.

3) Manyvariablestarsarebrighterintheinfraredthanatvisualwavelengths(somearemuchbrighter).eAurwasnoexceptiontothis;throughouttheeclipse,theJ-bandreadingswereabout0.5magnitudebrighterthaninV,whiletheH-bandreadingsrancloseto0.7magnitudebrighterthaninV.ThiscanbeseeninFigure1.

4) There are few infrared observers. While for some stars, visual-bandobservers (V in particular) will find their data lost in the crowd and socontributelittle,thisisnotthecaseintheinfrared.Forthedurationofthisproject(November2008–present)therewereonlytwoobserverssubmittingH-andJ-banddatatotheAAVSO.

5) Waterisanabsorberofinfraredradiation.Eventhoughtheskymaylookclear,therewillsometimesbetoomuchwatervaporintheair.Someofthenoisydatacollectedearlyintheeclipsewereduetoattemptsmadeonpoornights.

2. Equipment

The equipment used during the eclipse consisted of an Optec SSP-4photoelectricphotometerwithamanualfilterslideholdingH-andJ-bandfilters.TheH-andJ-bandfilterband-passesareclosesttotheMaunaKeaObservatory(MKO)andCaltech/Tololo(CIT)systems(Henden2002).Thegallium-arsenide(GaAs)detectorintheSSP-4isonemillimeteracross(about100arcsecondsatthefocalplaneofan8-inchSCToperatingatf /10).Aversionofthephotometerisavailablewithasmaller,0.3-mmdetector,butthesmallerdetectorgiveslesssatisfactoryresults(Hopkins2006a). TheSSP-4photometeristheresultofacollaborativeprogrambetweentheAAVSOandOptec,Inc.(West2007).Itcontainsaneyepieceforcenteringthetargetandcomparisonstars,aflipmirrorforsendingtheimagetothedetectoraftercentering,andafilterslidecontainingtheH-andJ-bandfilters;thefilterslideandflipmirrorareoperatedmanually. The software which Optec provided for use with the photometer wasutilizedformostoftheobservations,althoughanalternatesoftwarepackage,


written by Brian Kloppenborg at the University of Denver, was used onoccasion (Kloppenborg 2011). This software gave greater control over thephotometer,but theOptecsoftwaremadeabettermatchwith theparticularspreadsheetthatwasinuse.BothsoftwarepackagesranwithoutissueonanolderlaptopcomputerrunningWindowsXPPro.Thiscomputerwasusedforbothtelescopeandphotometercontrol.Thecomputerhad1GBofRAMandasingle-coreCeleronprocessor;ithadnoproblemscontrollingbothinstrumentsatthesametime. Threedifferenttelescopeswereutilizedduringtheeclipse:an8-inchMeadeLX200,aCelestronC14,andaMeade8-inchLX90.ThetwoMeadeSCTswerefork-mountedonequatorialwedges,whiletheC14wasmountedonaGerman-equatorial mount (GEM).All of the telescopes proved adequate to the task,althoughtheC14,duetoitslargeraperture,gavethebestresultsintheshortestperiodoftime.

3. Observations

Whenpreparationsbeganfortheupcomingeclipseduringthesummerof2008, an 8-inch Meade LX200 located at ETSU’s Powell Observatory wasutilized.Itisreportedthata10-inchtelescopeistheminimumusefulsizeforinfraredphotometryofeAurduetothefaintnessofthetraditionalcomparisonstar,lAur(Lucaset al.2006).lAurisfaintintheinfrared(magh=3.33,magj=3.62),makingitdifficulttousewithasmallertelescope.Thesolutionwastouseabrightercomparisonstar—theAAVSOrecommendationsfortelescopesunder 0.25 meter (10 inches) are to use Capella as the comparison star andbTau(elNath)asthecheckstar(Templeton2011b). ThetwoMeadetelescopeswerecontrolledwithMeade’sautostarsoftware.Althoughothercontrolsoftwarewastested,theMeadesoftwareprovedtobevery capable and worked well. The C14 was controlled using starry night pro 5,whichalsoworkedwell.Thegoalsinitiallywere:1)collectpre-eclipsedataoneAur,2)takemeasurementsofstandardstarstobeusedforcalibratingthephotometer/telescopecombination,and3)measureothervariablestarsontheAAVSO’sIRphotometrylist. The firstobservationsofeAuroccurredonNovember2,2008.The starwaskeptunderobservation(fromtheETSUobservatory)fromthatdateuntilitwaslosttothesuninlateMay2009.eAurwasre-acquiredonthemorningofJuly24,2009,andatthatpoint,itbecameobviousthattherewouldsoonbeaproblem.Theauthor’s“dayjob”isthatofahighschoolchemistryteacher—onceschoolbeganafterthesummerbreak,itwouldnotbepossibletomaketheforty-five-minutedrivetoETSUearlyinthemorning,getsetup,collectthedata,geteverythingputaway,andthengettoschoolintimeforthestartofclasses. Asearchforasuitabletelescopetousefromtheauthor’shomewasstartedand a usedMeade8-inchLX90 (UHTCcoatings)with an equatorialwedge


wasfound.Itwaspurchasedandsetuponaconcretepierattheauthor’shome.The LX90 was not as accurate as the LX200, but its tracking and pointingabilities were more than adequate for use with the 1-mm detector of thephotometer.TheonsetoftheeclipseinAugust2009waseasilydetected. Astheeclipsedeepened,itbecameapparentthatalargertelescopewouldgivebetterresults,asthebrightnessofeAurwasdecreasing.AdiscussionwithAAVSO DirectorArne Henden, while he was on a speaking engagement atETSU,ledtotheadvicethatlongertimeontargetwasonesolution(Henden2009).Thisworked,butthetimeinvolvedincreasedaswell. Atthispoint,about1.5hoursofcollectingdatawererequiredforthetwodatapoints(oneeachinHandJ).Theinfraredskyisnottransparentoverlongperiodsof time(Henden2002),especiallyintheSoutheasternUnitedStates.A larger telescope would allow shortened observation times. King College,in Bristol, Tennessee, offered the use of their Celestron C14 located at thecollege’sBurkeObservatory.Thecollege’sphysicsdepartmentalloweduseofthetelescopewhenitwasnotbeingotherwiseutilized. The C14 made a large difference in the S/N ratio. It was used for theremainder of that observing season, although a move back to the ETSUtelescopewasrequiredinlateMay(treesbecameanissue).Duringthelastyearoftheeclipse,theC14begantobeutilizedmoreoftenbyKingCollegeandsoobservationsmovedbacktotheLX90andtheLX200.Currently,theLX90istheprimaryinstrumentusedforpost-eclipsemonitoring.

4. Data collection

Priortoanight’sobservations,thephotometerwaspoweredupandhookedto the laptop computer. The photometer drew from its own external powersupply,butwascontrolledbysoftwareonthelaptopthroughaUSBcable.Thephotometer’stemperaturecontrolwassetto–40°Celsius(belowambient). Whenfirstturnedon,thephotometertypicallyproducedhighdarkcounts—thesedecreasedas the instrumentstabilized(30–60minutesafterpower-up).Thedarkcountswouldnormallydropslowlyduringtherun,butnotsofarthattheybecameaproblem.While thephotometerwasstabilizing, the telescopewassetup,polar-aligned,andplacedundercontrolofthelaptop(theC14waspermanently mounted, the other two telescopes were not). Prior to startingthedatarun,thephotometer’sdarkcountswerecheckedandthegaincontroladjustedtobringthemintotherangerecommendedbyHopkins(2006b).Thephotometerwasthensettoagainof100,witha10-secondexposure. The comparison star,aAur (Capella),wasmeasuredwithbothHand Jfilters.The telescopewas thenoff-set slightlyanda readingon the skywasmade,onceagaininbothfilters;thepatternusedwas“compH,compJ,skyJ,skyH.”Thetelescopewouldthenbepointedatthevariablestar(eAur)andthesamepatternrepeated“variableH,variableJ,skyJ,skyH.”Thenbackto


aAur where the pattern was repeated once again.The last measurement ofthenightwasofthecheckstar(bTau)sinceithadlowestpriority(SchmidkeandHopkins1990).Thisprocedureproducedonedatapoint ineachfilter.Aminimumofthreesuchobservationswererequiredsothatmeaningfulstatisticscouldbecalculated;more than threeobservationswerenecessarydue to thesmallsizeofthetelescopesused. Thephotometer software,providedbyOptec,allowed thephotometer totake one exposure, three sequential exposures, or four sequential exposures.Whentheprojectfirstbegan,threeexposuresoftensecondseachweretaken,followedbythreeexposuresontheskyandthenbacktothecomparisonstarwherethreemoreexposuresweremade(accordingtotheabovedescription).Thesethreeobservationswerethenaveraged.Thiswasrepeatedatleastthreetimes(orfiveorseven,andsoon.).Eachgroupofthreereadingswasaverageddown toone readingand then the three (or fiveor seven, and soon) singlereadingswereaveraged togivea singlenumber for the star’sbrightness forthatnight’sobservations.Thiswasthenrepeatedusingtheotherfilter.Thetimeinvolvedforthiswassignificant,especiallyinthebeginning. Thismethodworkedwell,exceptwhentheskywasrapidlychangingorforobservationsmadeathighairmass—theskywouldsimplychangetooquicklybetweenonemeasurmentandthenext.ItwasrealizedthataveragingthedatatwicedidnothelpintermsofS/Nandaddedagreatdealoftimetotheoperation.Astheeclipseneareditsend,“singleshot”readingsbegantobetaken—comp,sky, var, sky, comp, sky—one reading each, not grouped into threes. Thisproduceddatathatweregenerallybetter,ifthestarswereunderchangingskyconditions,thanthe“groupofthree”methodmentionedabove.Becauseofthespeed at which the readings could be taken, data could be collected at highairmassandstillnotbetoonoisy. Originallythispatternwasrepeatedthreetimes,butitwasfoundthatthetotalcountswerelow,(exceptwhenusingtheC14),soitwasincreasedtofivesets,thentoseven,andfinallytoninesets.Ninerepetitionswerenotpractical,soeventuallysevensetsweresettledupon—thisgavethebesttrade-offbetweentimeinvolvedandS/Nratio.

5. Data reduction

AMicrosoftexcelspreadsheetwasdeveloped,usingaformatthatallowedtheobservertosimplycutandpastthedatafromthephotometer’snativeoutputfiledirectlyintothespreadsheet. The data output of the photometer contained columns of data,representingsuchthingsasdate,time,filtersused,gainsettings,lengthofexposure,andnumberswhichrepresentthephotonsdetectedduringtherun.Itwas inanexcel-readable format.Severalquantitiesmustbecalculatedfromthisinformation:


1) Thetelescope’slocation—thisinformation,alongwiththesiderealtime,wasneeded tocalculate the localhourangleand from that, atmosphericextinction,

2) TimeanddateoftheobservationconvertedintoJulianDays—thedatarunconsistedofseveralreadingssothetimestampofthecentralvalueofthesetwasusedasthetimeofobservation.

3) Filtersused—theexcelsheetdidnotutilizethesedata,butitallowedsortingofthedatapriortopastingthemintothespreadsheet.

4) Gainandexposuretimes—thisinformationwasusedtoreducethetotalcountsdownto“countspersecond”sothebrightnessofthestaratthetimeoftheobservationcouldbedetermined.

Theaveragedphotometer readingsmentionedpreviously represented thenumber of photons that arrived from the target star during each exposure.Severaladditionalcorrectionstotheserawcountswerenecessaryinordertoget thestar’s truemagnitudeineachfilter.Asummaryoftheproceduresarelistedbelow.ThefullproceduresandequationsusedmaybefoundinHendenandKaitchuck(1982),Hall(1988),andSchmidkeandHopkins(1990):

1) Converttherawcountsintoinstrumentalmagnitudes.

2) Calculatethedifferenceinbrightnessbetweenthetargetstar(eAur)andthecomparisonstar(aAur).ThevalueusedforaAurwastheaverageofthereadingstakenjustbeforeandjustafterthereadingoneAur.

3) Apply an extinction correction to the differential magnitude of thetargetstar.Thisextinctioncorrectionisnecessaryduetothedifferenceinairmassesbetweenthecompandtargetstars.InthecaseoftheaAur-eAurpair,thedifferencewasslightwhilethestarswererisingintheeast(latesummer),butincreasedastheytraveledwestward,reachingamaximuminlatespring.

4) Applyacorrectionfortheinstrumentalcolorresponseforthesystem—thisfinalcorrectionadjuststhemagnitudestothestandardsystem.

Thereareother,additionalcorrectionsthatcouldhavebeenperformedonthedata.However,theimpactofthosecorrectionsisveryslightintheinfrared(Henden1982)andsothosecorrectionswerenotmade.

6. Results

Althoughthisprojectwasprimarilyinstrumentalinnatureandnotanalytical,someconclusionsabouttheeclipsecanbedrawnfromthedata:


1) eAur is fainter in the J band than in the H band, both in and out ofeclipse(seeFigure1).

2) Thebackgroundvariationsoftheprimaryareevident,bothinandoutofeclipse(Figure1).

3) Thesecondhalfoftheeclipseisnotasdeepasthefirsthalf—perhapsthetrailingsideofthediskisthinnerthantheleadingsideoritmightnotcovertheprimarytoasgreatanextent.

4) Acomparisonoftheratesofchangeduringingressandegressinbothfiltersshowthattheeclipseendedatagreaterratethanitbegan.ThiscanbeseeninFigures2and3.Theslopesoftheingressstageswere0.0045mag./JDinHand0.0048mag./JDinJ,whilethoseoftheegressportionswere0.0060mag./JDinHand0.0067mag./JDinJ.

Theseslopesareveryshallowduetothelongdurationoftheeclipse.Datapointsformakingslopedeterminationswerechosenfromwhenboththeingressandegressstageswerewellunderway.

5) Bytakingtheslopesofthepre-andpost-eclipsestagesandoverlayingthemontheslopesoftheingressandegressstages,itispossibletodeterminethedatesoftheeclipse’sonsetandendingintheHandJbands.

An examination of Figure 2 and Figure 3 shows that the eclipse beganaroundJD2455046 inHandJD2455057 in J (3August2009 inHand14August2009inJ).Thereisalargeamountofscatterinthepre-eclipseJbanddatapointsandthismightexplainthevariationinthestartingdatesbetweenthetwofilters.TheeclipseappearedtoendonJD2455707inboththeHandJbands(26May2011).

7. Conclusions

Near-infrared photometry in the H and J bands can be successfullyundertaken using a telescope of modest size, such as an 8-inch Schmidt-Cassegrain. Care should be taken in the choice of comparison, target, andcheckstarsinordertokeepsignal/noiseratiosashighaspossible.TheeAureclipsedidfallwithinthereachofthistypeofsetup,butatitsdeepest,thedropintheS/Nratiowasveryapparent.Targetstarsforsuchasetupshouldbebrighterthanaboutmagnitude2inthechosenfilters,ifpossible.Fainterstarscanbemonitored,butrequirelongdatacollectiontimesinordertokeepthesignalatacceptablelevels.


8. Acknowledgements

Theauthorwouldliketothankthefollowingindividualsandinstitutionsfortheirguidanceandassistanceinthisproject:Dr.GaryHenson,ETSU;Dr.Beverly Smith, ETSU; Dr. Ray Bloomer, King College; Dr. Edward Burke,KingCollege(deceased);ETSUDepartmentofPhysicsandAstronomy;andtheAmericanAssociationofVariableStarObservers. Specialthankstomywifeandfamilyforallthelonghoursandcomplaintsabouttheclouds.

References

Hall,D.S.,andGenet,R.M.1988,Photoelectric Photometry of Variable Stars,Willmann-Bell,Richmond,VA.

Henden,A.A.2002,“JHKStandardsforSmallTelescopes”(http://www.aavso.org/sites/default/files/webpublications/ejaavso/v31n1/11.pdf).

Henden,A.A.2009,privatecommunication.Henden,A.A., and Kaitchuck, R. H. 1982, Astronomical Photometry, Van

NostrandReinhold,NewYork.Hopkins,J.L.2006a,“PhotoelectricPhotometryWhitepaper,SSP-4Detector”

(http://www.hposoft.com/Astro/SSP-4/WhitePapers/Detector.html).Hopkins,J.L.2006b,“PhotoelectricPhotometryWhitepaper,SSP-4Observation

Techniques”(http://www.hposoft.com/Astro/SSP-4/WhitePapers/Techniques.html).

Kloppenborg,B.2011,“SSP-4ControlSoftware”(http://finiteline.homeip.net/redmine/projects/ssp-4-control/wiki/Wiki).

Lucas, G. A., Hopkins, J. L., and Stencel, R. E. 2006, in The Society for Astronomical Sciences 25th Annual Symposium on Telescope Science,SocietyforAstronomicalSciences,RanchoCucamonga,CA,25.

Schmidke, P. C., and Hopkins, J. L. 1990, Workbook for Astronomical Photoelectric Photometry,HPODesktopPublishing,Phoenix,AZ.

Stencel,R.E.2011,“APrimaryNodeintheEpsilonAurigaeEclipseCampaign”(http://mysite.du.edu/~rstencel/epsaur.htm).

Templeton, M. 2011a, “Infrared Photoelectric Photometry Program” (http://www.aavso.org/infrared-photoelectric-photometry-program).

Templeton, M. 2011b, “SSP-4 Targets and Comparison Stars” (http://www.aavso.org/ssp-4-targets-and-comparison-stars).

West,D.2007,“Single-ChannelInfraredPhotometrywithaSmallTelescope”(http://www.bellatrixobservatory.org/cvaaI/28/).


Figure1.TheeAureclipse(2009–2011)inV,H,andJ.eAurisbrighterinboththeHandJbandsthanintheVbandinboththein-andout-of-eclipsephases.Thebackgroundvariationsoftheprimarystarcanalsobeseen.(DatacourtesyAAVSO).

Figure2.TheeAureclipse(H).Oncetheingressstagewaswellunderway,theeclipseproceededattherateof0.0045mag./JDinH.Onceegresshadbegun,eAurbegantobrightenattherateof0.0060mag./JulianDayinH.Thedatesofeclipseonsetandeclipseendcanbeseenbydeterminingwherethepre-andpost-eclipseslopescrosstheingressandegressslopes.


Figure3.TheeAureclipse(J).Theingressphase(Jband)ofeAurproceededattherateof0.0048mag./JD.Asegressoccurred,itproceededattherateof0.0067mag./JD.Thedatesof eclipseonset andeclipse endcanbe seenbydeterminingwherethepre-andpost-eclipseslopescrosstheingressandegressslopes.

Griffin and Stencel, JAAVSO Volume 40, 2012714

UV-Blue (CCD) and Historic (Photographic) Spectra of e Aurigae—Summary

R. Elizabeth GriffinDominion Astrophysical Observatory, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada; [email protected]

Robert E. StencelDepartment of Physics and Astronomy, University of Denver, 2112 East Wesley Avenue, Denver, CO 80208; [email protected]

Received March 19, 2012; accepted March 27, 2012

Abstract Whiletherearenumerous“newspectroscopicstudies”ofeAurigaereportedinthisspecialeditionofJAAVSO,theonesummarizedhereisbelievedtobeuniqueontwocounts:itconcentratesontheblueandnear-UVspectralregions, and it incorporates historical spectra from the previous eclipses of1983and1956.Themoredatathatcanbecollated,acrossallwavelengthandtimebase-lines,themoreconclusivethefinalmodelofthisbafflingobjectislikelytobe.Amorelengthypaperthatincludesillustrationsofthespectraisbeingpreparedforpublicationelsewhere.Thisshortcontributionsummarizestheeffort thathas so fargone intodata acquisitionandpreparation, and theprincipalresultsthatarenowemerging.

1. Data: recent CCD spectra

Wehaveobservedandanalysed~150newCCDspectraofeAurigaeatblue and near-UV wavelengths, recorded during the 2010 eclipse with thecoudéspectrographoftheDominionAstrophysicalObservatory(DAO)1.2-mtelescope.Thewavelengthspanobservableinoneexposureisabout145Å,sowetargettedspectralregionsofspecificinterest,andmonitoredjust thoseasopportunitypermitted.Thegreatmajoritywascentrednearl3950Åsoastoinclude theCaiiHandK linesand thenearbystrongground-stateFei lines;somewhatlessfrequentmonitoringwascentredonHdandspannedthestronglow-excitationFeilinesbetweenl4045–4071Å,andacomparablenumberofspectrawerecenteredneartheMgiidoubletatl4481Å,whereausefulmixtureoflow-andhigh-excitationlinesoccurs.Someobservationswerealsomadeintheredspectralregion,nearHa.Allthespectrawerereducedintheworldco-ordinatesystembyasemi-automaticpipeline,andwerethenextractedinstepsof0.01Åandlinearizedtoanapparentcontinuumheightof100%.IforiginalS/Nratioswereratherlow,sequentialspectrawereco-added.

Griffin and Stencel, JAAVSO Volume 40, 2012 715

2. Data: historic photographic spectra

Wedigitizedover130historicspectraofeAurfromMountWilson(datingback to the1930s) and from theDAO(dating from1971)using theDAO’sPDSmicrophotometer, resurrectingandadoptingprocedures thathave stoodthe test of time. Spectrophotometric calibrations were determined by meansofspecialexposurestoalightsourcethroughaperturesofknowngeometricalcharacteristics.Thosespectrawerealsoextractedinregularstepsof0.01Åandlinearizedtothelocalstellarcontinuum.ManyhadveryacceptableS/Nratios,thoughnonequiteashighascanbeachievedwithamodernCCDdetectoronabrightstar.Nevertheless,theseheritagedatacontributeuniquelytothisstudy,byrevealingwhichofthemanyline-profilechangeshaverepeatedatidenticalphasesofpasteclipses,therebyfurnishingimportantconstraintsforamodelofthestructureandformationoftheoccultingdisk.TheycouldthenbemergedwiththerecentCCDonessoastoprovideamorecompletedataset,whichweexaminedbyrangingeachspectralregionwithphase,withinthewavelengthspansdefinedbytheCCDspectra.

3. Properties of the disk

We adopted the parameters of the radial-velocity orbit of Stefanik et al.(2010)(P=9896.0±1.6days,K=13.84±0.23kms–1,T=HJD2434723±80),andalignedthespectrainthevelocityrest-frameoftheFstar.Thezerophaseofthatorbitsolutioncorrespondstoperiastron,sophotometriceclipsebeganclosetophase0.056andendedclosetophase0.130.Mid-eclipse(secondaryconjunction)wasatphase0.091. Manyauthors—e.g.,Struve(1956),Wright(1958),Hack(1962),LambertandSawyer(1986),andFerlugaandMangiacapra(1991)—havedrawnattentiontocuriousline-profilechanges,particularlyduringearlyingressandlateegress,oftenreferringtothemas“linedoubling.” (a)Theprincipalline-profilechangesaretheextraabsorptioncomponentsthatbecomesuperimposedonground-stateandlow-excitationlines.Thenewfeaturesarered-shiftedduringingressandblue-shiftedduringegress,andarebestseeninlinesofFeionaccountofthelatter’sstrengthandnumber.Thelinesthemselvesdonotactually“split,”sincethetwodistinctcomponentsoriginateinquitedifferentregionsofthesystem. (b)ComparisonsoftheFeiprofilesatdifferenttimesfurnishlimitstothephases (and hence on the geometry) when that “doubling” commenced andceased. It is apparent that the occulting disk has a “tail” which trails muchmoreextensivelythandoesanymaterialatitsleadingedge.Ourspectraalsodemonstrated the existence of more rarefied material in the extremes of the“tail,”notunlikethatinacool-starchromosphere. (c)Comparisonsofspectraofthesamephasesbutdifferentorbitalcyclesindicatethatthestructureofthediskisstable,atleastonatime-scaleofacentury

Griffin and Stencel, JAAVSO Volume 40, 2012716

orso:thesame“line-doubling”recursatidenticalphasesanditscharacteristicsrepeatquiteprecisely. (d)Extra-narrowdiskfeaturesinbothingressandegresssuggestregionsofexchangeofmaterial(betweenthediskandthesupergiant)thatarehighlyconfinedinbothdirectionandvelocity.

4. Instabilities in the F star

At all orbital phases the spectra of the system reveal more subtle line-profilechanges:theabsorptionlineswhichpresumablyoriginateintheF-starphotosphere(sincetheyshownophase-relatedvelocitychanges)canweaken,orbroaden,orstrengthenalittle.Dividingallspectraofagivenregionbyonerecordedfarfromeclipseaccentuatesthechanges,andshowsbroademissionfeaturesthatgrowandfadeatallphasesontime-scalesofdaysorweeks,withassociated narrowing (or deepening) of the K-line wings resembling a rise(orfall)inTeff.Fortherecenteclipse,therewassomeevidenceofcorrelationbetweenthegrowthofemissionandtheCepheid-likepulsationsof~67days’period (Kim 2008), but the recorded photometry had not been sufficientlyplentifulinthepasttoinvestigatesuchcorrespondencesinearlieryears,noraretheavailablespectraadequateforathoroughinvestigation:aquarter-phaseisonly17days,andspectramustcorrespondtonullormaximum—arequirementthatisunlikelytobefulfilledgiventheeclecticnatureofthearchivaldataforasystemofsuchlongperiod.

5. The spectrum of the disk

The absorption of the disk itself can be isolated by dividing eclipse-phase spectra by one of the system far from eclipse.The procedure cannotbe fully precise or absolute because of the small intrinsic variations in thesystem’sspectrumreferredtoabove;thediskspectrumalsocontributestothesystem’soneatallphases,thoughthosecontributionsaresmallcomparedtothe substantial absorptionwhich theedgesof thediskcreateduringeclipsephases.Theprime features thatwe thus isolateare the red-shifted (ingress)andblue-shifted (egress) absorption lines; theyvanishduring thephasesofcentral eclipse. Their respective velocity displacements are surprisinglyconstant,andwhilebothareconsiderablysharptheblue-shiftedonesappearbroaderatphaseswhichareactuallybeyondtheendofphotometriceclipse.Itisthereforeonlyattheleadingandtrailingedgesofthediskthatopticallythinmaterialissufficientlyconcentratedtogiverisetodetectableabsorptionfeatures.However,thepresenceofvariableemissionalsointhesystemrequiresmodellingbeforeaquantitativeassessmentofthepropertiesofthatabsorbingmaterialcanbemade. Qualitatively,thediskfeaturesareverysimilartotheabsorptionlineswhichariseinacool-starchromosphereandwhichcanbeisolatedduringingressor

Griffin and Stencel, JAAVSO Volume 40, 2012 717

egressphasesofan“atmospheric”eclipseinazAursystem.ThelinesineAurare ground-state or low-excitation transitions of easily-ionized elements likeTiiandFei,whereastherearenocorrespondingfeaturesinMgiil4481Å,forexample.Aswithastellarchromosphere,thetotalabsenceoflinewings,evenforhydrogenlines,indicatesasurfacegravity,logg,<1. Acomparisonbetweentheingressandegressfeaturesofthediskshowsthatthediskisnotsymmetrical:itsleadingedgeismorecompressedthanitstrailingedge.Althoughthevelocityshiftsarelargelyconstant,duringtheextremeendof theegressphases(phase~0.125onward) theblue-shift invelocitybeginstodecrease.Aroundthesametimethesharpnessofthefeaturesisparticularlyaccentuated.ThoseobservationssuggestthatweareseeingmaterialwhichisflowingalongaveryconfinedpathfromtheFstartothedisk.

6. Transient absorption lines during egress

Afewweak,narrowabsorptionlinesappearonlybetweenphases0.111and0.123(orpossiblylater).Theyhaveaconstantvelocityoffsetthatmatcheswhatisshownbythesharpegressfeatures,andtheirappearanceswererepeatedatidenticalphasesinearlierorbitalcycles.Mostappeartobelow-levellinesofFei,thoughnotallhaveyetbeenidentified.Thecuriouslytightrestrictioninphasesuggestsanenhancedabsorbingmechanismwhichcomesintoplayonlyduringthesecondstageofegress;thereisnocounterpartduringingress.Theirremarkablesharpnessisprobablylimitedbytheresolutionoftheobservationsandisthereforeonlyanupperlimit;ameasuredhalf-widthsuggestsanupperlimitof~9kms.

7. Acknowledgements

WeacknowledgethesupportoftheHIA/DAOingrantingobservingtime,whenmanyspectraofthe2010eclipsewereobtained.WearealsogratefultotheDAOandtoMountWilsonObservatoryfortheloanoftheirphotographicspectraofthesystem,andtotheAmericanAstronomicalSocietyforaSmallResearchGranttodigitizethem.

References

Ferluga,S.,andMangiacapra,D.1991,Astron. Astrophys.,243,230.Hack,M.1962,Mem. Soc. Astron. Ital.,32,351.Kim,H.2008,J. Astron. Space Sci.,25,1.Lambert,D.L.,andSawyer,S.1986,Publ. Astron. Soc. Pacific,98,389.Stefanik,R.P.,Torres,G.,Lovegrove,J.,Pera,V.E.,Latham,D.W.,Zajac,J.,

andMazeh,T.2010,Astron. J.,139,1254.Struve,O.1956,Publ. Astron. Soc. Pacific,68,27.Wright,K.O.1958,Astron. J.,63,312.

Mauclaireet al., JAAVSO Volume 40, 2012718

Ha Spectral Monitoring of e Aurigae 2009–2011 Eclipse

Benjamin MauclaireObservatoire du Val de l’Arc, route de Peynier, 13530 Trets, France; [email protected]

Christian BuilCastanet Tolosan Observatory, 6 place Clémence Isaure, 31320 Castanet Tolosan, France

Thierry GarrelObservatoire de Juvignac, 19, avenue du Hameau du Golf, 34990 Juvignac, France

Robin LeadbeaterThree Hills Observatory, The Birches, CA7 1JF, England

Alain Lopez529 rue Buffon, 06110 Le Canet, France

Received February 22, 2012; revised May 30 2012; accepted May 30, 2012

Abstract Wepresent and analyzeeAurigaedata concerning the evolutionoftheHalineontheoccasionofthe2009Internationalobservationcampaignlaunchedtocovertheeclipseofthisobject.WevisuallyinspectthedynamicalspectrumconstructedfromthedataandanalyzetheevolutionwithtimeoftheEW(EquivalentWidth)andoftheradialvelocity.Thespectroscopicdatarevealmanydetailswhichconfirm thecomplexityof theeAur system.Theobjectis far from being understood. In particular, according to our measurements,theeclipsedurationhasbeenunderestimated.Acompleteanalysisofdetailsrevealed by our data would require much time and effort. Observers areencouragedtocontinuemonitoringtheHalineoutofeclipseinthehopethatitwillprovidefurtherimportantinformation.

1. Introduction

eAurigaeisoneofthemostintriguingeclipsingstarsystemswhichhaspuzzledastronomersfornearly200years.Themaineclipsingperiodiscloseto27.1yearsandthefirstspectroscopicsurveyswereundertakenduringthe1929and1956eclipses.Alargecampaignwasalsoorganizedfor1982–1984.Forareviewofliteraturepriortothe2009–2011eclipse,seeGuinanandDeWarf(2008).Therearealsonumerouspapersbeingpreparedasaresultofthe2009–2011eclipse.Despite the concentrated efforts, someaspectsofeAurremainamystery.

Mauclaireet al., JAAVSO Volume 40, 2012 719

eAurisclassifiedasanA8IabstarinanAlgoltypeeclipsingbinarysystem(simbaddatabase2011).TheprevailingmodelisofanF-typestarwithahotclumpyHydrogendiscandanobjectofunknownnaturewhichproducesaneclipse phenomenon lasting almost 2 years every 27.1 years.There may beamid-eclipsebrighteningbut solarproximitymakes thephotometry suspectat those times. Recently, it has been suggested that the eclipsing object is a550Kdustydiskseenedgeon,heatedonthesidefacingtheFstarto1100K.ThisdiskmaycontainaB5Vstar(Hopkinset al.2011)thatcouldcontributeto emission wings surrounding Ha line. Light curves feature 0.1 magnitudevariationsbothinsideandoutsideeclipse.VariationshavealsobeenobservedintheEquivalentWidth(EW)andRadialvelocityofspectrallinesoutsideeclipse.ThesevariationsmightbeFstaroscillationsandwind. Duringthe1982–1984eclipse,thisstarwasstudiedbyamateurobserversusing multiband photometric methods. The e Aur system was not clearlydescribeddespitealltheacquireddata. Twenty-seven years later, an international campaign was organized tomanagebothspectroscopicandphotometricobservationsbyamateurobserverswiththeaimofproducingdatawithimprovedtimeresolutioncomparedwiththat achieved during previous eclipses. In this article, we present amateurspectroscopicHalinemonitoringfromFebruary12,2008,toNovember12,2011.

2. Observations

In 2008, Jeff Hopkins (http://www.hposoft.com/Campaign09.html)organizedtheinternationalobservationcompaignofthe2009eAureclipse.Weacquiredmorethan250highresolutionspectraoftheHalinecoveringthethreeyearsaroundeclipse.Theseshowsignificantvariabilitythroughoutthisperiod.TheeffectoftheeclipseisclearlyseeninthislinefromtheendofApril2010toendofApril2011.ThespectrausedforthisstudywererecordedbyfiveobserversinEurope. Most observations were made using LHIRES3 spectrographs (LHIRES3andeShellareproductsfromShelyakInstrument,Grenoble,France:http://www.shelyak.com). C. Buil used an eShell spectrograph that covers wavelengthsfrom4500Å to7000Å.Telescopediameterswerebetween0.2mand0.3m.Spectralresolutionisabove10,000andmostofthetimearound15,000.Meanexposuretimewas2,000s.AllsetupsarereportedinTable1.

3. Reduction and analysis method

TherawobservationsareavailablefromRobinLeadbeater’seAursurveywebpage(http://www.threehillsobservatory.co.uk/).Thespectrawerereducedusingstandardprocedurestoproducecalibratedandnormalizedlineprofiles.Most of the reduction was done using SpcAudace (http://bmauclaire.free.


fr/spcaudace/) pipelines.The reduction steps were: preprocessing, geometriccorrections, and registration. Then line profiles were extracted with skybackground subtraction. Wavelength calibration was done using calibrationlampspectrabeforeandaftereachacquisition series tominimise theeffectsofcalibrationdrifts.The instrumental responsewas then removed.Anoffsetwas computed using telluric lines to achieve a final wavelength calibrationRMS uncertainty of 0.03Å. Finally a heliocentric velocity correction wasapplied depending on the observation date. All wavelengths l are giveninÅ(Ångström). Equivalent Width (EW) measurements were computed betweenl6550 and l6577 using linear integration and an extracted continuumobtained from a fit to the local star continuum (about EW’s computation:http://bmauclaire.free.fr/astronomie/spectro/experiences/ew/ewconvention/).The Chalabaev algorithm (Chalabaev 1983) was used to estimate theuncertainty,whichismostlydependentonthesignal-to-noiseratio,andappearsto overestimate the uncertainty compared with the actual scatter observedaroundthelongtermtrend. Radial velocity is computed in two steps because the Ha line isasymmetric:

• TheGaussianflankof the linewasreproducedon theoppositesideofthesymmetryaxis(theoreticalwavelengthoftheline)andshiftedtofittheline’soppositeflank;

• AGaussianfitofthesetwoflanksgaveameasureofthelinecenter.

A dynamical spectrum was computed using 177 spectra corrected toheliocentricvelocityandcroppedtol6550–l6575.Alinearinterpolationwasusedtoproduceanimagewitha1-daysamplinginterval.Suchinterpolationdoesn’tintroducebiasforouranalysisasthepurposeofFigure6istoshowglobal behavior of the eclipse spread over several hundred days. Dates arelogged in MJD (that is, JD–2400000). All computations were performedin SpcAudace. The monitoring covers a period of 720 days. Most of theinformationgeneratedbyourmonitoringof theHa line iscontainedin thisdynamicalspectrum. Analyzing this complex image turns out to be cumbersome, however.Thisisthereasonwhywehavesimplifiedtheanalysisbyconcentratingonthe evolutionwith timeof theEW that canbe compared toVmagnitude,andoftheradialvelocitythatcanbeusedtostudyeclipsingphenomena.Ofcoursewehave tokeep inmind thatEWloses itsphysicalmeaningwhenappliedtocomplexlineprofileslines,asitisthecaseforeAur,arelikelytoresultfromacombinationofseveralsources.Butbeforeanalyzingthesequantities, letus firstexamine thespectral lineprofilesatdates thatshowimportanttransitions.


4. Behavior of the wings

Outside eclipse, the Ha line profile comprises a central absorption coreflankedbyemissionfeaturesontheredandbluewings(seeFigure1).ThesefeaturesarehighlyvariableasdescribedbyGolovin(2007). IntheregionoftheHalineareabsorptionlinesidentifiedastelluriclinesatl6543.91,l6547.71,l6548.32,l6552.63,l6557.17,l6568.81,l6572.09,l6574.85,andl6586.68. Aswecan see inFigures2and6, fromMJD55250onwards therewasadditionalabsorptioninthecorewhichbroadenedrapidly,engulfingfirsttheredemissionandbyMJD55340alsotheblueemissioncomponent.NotethisisincontrasttotheKIl7699lineabsorptionwhichstarteddecreasinginintensityduringthisphase(Leadbeateret al.2011). During ingress and into totality (see spectra atMJD55390.44andMJD55496.42) through the mid-eclipse point, the absorption core deepened andbroadenedslightlyontheredside.Theadditionalabsorptionmovedtotheblueand,atMJD55520,theredemissionfeaturereappeared. Atthebeginningofthedecreasingphase(seespectrumatMJD55627.46),the Ha line became narrower, with an emission component at the red side.Then,fromMJD55853.42,theblueedgeemissioncomponentreturnedasjustbeforeeclipse.Afterthemaineclipsephase(seespectrumatMJD55878.39),theblueandredwingswerebothpresentbutsmall,startingtoresemblethepre-eclipseprofile(Figure1). Attheendofthesurveyperiodtherestillappearstobeanexcessabsorptiononthebluesideofthecentralabsorptionregioncomparedwithtypicalpre-eclipsespectra,possiblyduetothecontinuedpresenceoftheeclipsingdisc.However,the inherent variability of this at all phases makes the statement uncertain. Today’sunderstanding(Stencel2011)isthattheFstarissemi-stableandcapableofproducingvariabilityinlinesinandoutofeclipse.Thediskisonlymodifyingtheopticalspectrumduringitspassage.

5. EW evolution with time

EWmeasurementswerecomputedbetweenl6550andl6577.Althoughthesignal-to-noiseratiovariesbetweenobservationsandincludestelluriclineswhichimpactonEW,theeffectmostofthetimeisrathersmall.ThedataqualityallowsareliableestimationoftheEW.Asmentionedearlier,thesinglequantityEWisagrosssimplificationofthecomplexnatureoftheline. However, this quantity is the integral of the distribution of luminosityversus wavelength. It can thus be compared to similar integrals such as theV magnitude.As shown in Figures 3 and 4, equivalent width (EW) and Vmagnitude(Vmag.)areanti-correlated.GiventhatEW>0forabsorptionlines,theeclipsingobjectoccultstheFstarHydrogendiskasfirstminimuminEW


andinVmag.evolutionarebothclosetoMJD55250,andassecondminimumand V magnitude evolution are also both close to MJD 55630. These datesdefinetotalityinnerlimits(seeTable2). Whilesecondandthirdcontacts(andmid-eclipse)timesarewell-definedbyourEWasafunctionofDatetrend(Figure3),thedefinitionoffirstandfourthcontacttimesarelessobvioushereanddonotcorrespondtophotometriccontacts:thesedates(secondandthirdcontacts)arelikelytobelinkedwiththedensestendsoftheeclipsingobject. Duringtheeclipsephaseandoutsideittoo,therearemanysmallvariationsinEWandVmag.ThissuggeststhattheoccultingobjectandFstarHydrogendiskmaybeclumpy.TheFstarmayhavealsoanintrinsicpulsatingactivity(Kempet al.1986;Stencel2011)thatproducessuchvariations. Ha EW has irregular variations like small steps during its increasinganddecreasingphases.SimilarbehaviorhasbeenobservedontheKIl7699asborptionline.Ithasbeeninterpretedasanindicationofstructures(possiblyring-like)withinthedisc(LeadbeaterandStencel2010).Continuedobservationduringegressmayhelptoclarifythis.

6. Radial velocity evolution with time

Figures 2 and 6 show how shapes are shifted in radial velocity.During the beginning phase of the eclipse (see spectra at MJD55390.44 and MJD 55496.42), the absorption line became red shifted(+14.79±1.37km/s). During the end phase of the eclipse (see spectrumat MJD 55627.46), the Ha line first returned to the position seen atMJD 55390.44 and then the absorption line still remained blue shifted(–31.59±1.54km/s at MJD 55853.42). See Table 3 for measurements atkeydates. Anemissioncomponent(Figure5)appearedinthecoreoftheHalinecloseto the restwavelength fromMJD55150onwardas theabsorption increasedinthisregion.Thisbecamemoreclearlydefinedasthesurroundingfluxleveldroppedfurtherandmovedacrosstheregionfromredtoblue.Theshapeoftheemissioncomponentisrevealedastheabsorptionregionbroadenedandsweptacrossitthroughmideclipse.Itisclearthattheconstantemissioncomponentisonlyrevealedasthesurroundingfluxleveldrops. Duringoursurvey,theemissioncomponentmeasuredbygaussianfittingremainedcenteredon6562.71±0.03Å,which, in termsof radial velocity,amountsto–4.97±1.54km/s.ThisdoesnotaccountfortheeAursystemicradialvelocityestimatedat–2.26±0.15km/s(Stefaniket al.2010),leadingtoacorrectionof+0.049Å(that is,+2.26km/s).NotethatFigure6isnotwellenoughresolvedtoseesuchasmallshift.Computationsweredoneonthelineprofiles.


7. In quest of new models

ThelightvariationsofeAurinandoutofeclipsehavebeentheobjectofmanystudies. During1983eclipseKempet al.(1986)analyzedpolarizationdata.TheysuggestedthattheFstarisanon-radialpulsatorandthatitssurroundingdiskistiltedwithrespecttotheorbit. In 1991, Ferluga and Mangiacapra (1991) suggested that to explain theshape of the light curve, the disk is not a continuous aggregate of dust, butinsteadaseriesofringswithaCassini-likedivision.Thismodelwasmoreorlessvalidatedbyobservations. Duringthiseclipse,awidevarietyofobservationshavebeenundertaken:infrared, ultraviolet, interferometry, photometry, and high resolution spectralmonitoring.Thus,aconsiderableamountofinformationisnowavailable(seeStencel2010;Hopkinset al.2011foranoverview).Itnowremainstodevelopamodelthatfitsallthedataathand.Undoubtedly,thehighresolutionspectralmonitoringdatawillbeveryimportantforconstrainingthesesmodels.

8. Conclusions

Our Ha monitoring ofeAur shows that, contrary to what was forecast,the effects of the eclipse extended beyond December 2011. Post-eclipseobservationsareneeded.R.Stencelwelcomesanyoutsideeclipsespectroscopiccontributions to thecampaignover thecomingmonthsandyears,especiallythosecoveringtheNaDlines. Wehaveobservedsimilaritiesanddiscrepanciesbetween theEWandVmagnitude evolution with time. The discrepancies remain to be explained,but that isbeyond thescopeof thisarticle.Wealsowereable todefinekeydates in theeclipsingphenomenon.However,much remains tobeanalyzed.ObviouslytheHamonitoringbringsalotofinformationwhichshouldplacemanyconstraintsonthemodelsconceivedbyscientistsabouteAur. Amateur spectroscopists are now able to monitor bright targets with aspectralresolutionofabout15,000.Suitablyequippedamateursconstituteateamwith long termmonitoringcapacitywhich iswidelydistributedovertheplanet. Inanycase,wehopethatthisinformationwillhelpscientiststosolvethemysterieshiddenbehindthisfascinatingobject.

9. Acknowledgements

This campaign would not have been possible without Jeff Hopkins’motivation and constant efforts to encourage amateur observations. Theauthors acknowledge Robert Stencel for his help and encouragements


thoughoutthiscampaign.Theyalsokindlythanktherefereeforconstructivecommentsandveryhelpfulwork. Allofthedatapresentedinthispaperwereobtainedfromamateurobservers.The authors also acknowledge Eric Barbotin, Stéphane Charbonnel, ValérieDesnoux, Stanley Gorodenski, Keith Graham,Torsten Hansen, James Edlin,BrianE.McCandless,ÉricSarrazin,LotharSchanne, JoséRibeiro,FrançoisTeyssier,OlivierThizy,andJohnStrachanforalltheworktheycarriedoutatotherwavelengthsandspectralresolutionsonthismysteriousstar.

References

Chalabaev,A.,andMaillard,J.P.1983,Astron. Astrophys.,127,279.Ferluga,S.,andMangiacapra,D.1991,Astron. Astrophys.,243,230.Golovin,A.,Kuznyetsova,Y., andAndreev,M.2007,Odessa Astron. Publ.,

20,55.Guinan, E. F., and Dewarf, L. E. 2002, in Exotic Stars as Challenges to

Evolution,eds.C.A.ToutandW.VanHamme,ASPConf.Ser.279,Astron.Soc.Pacific,SanFrancisco,121.

Hopkins, J., Stencel, R., and Leadbeater, R. 2011, Epsilon Aurigae Eclipse International Campaign Newsletter,No.24(Fall/Winter).

Kemp,J.,Henson,G.,Kraus,D.,Beardsley,I.,Carroll,L.,Ake,T.,Simon,T.,andCollins,G.1986,Astrophys. J., Lett. Ed.,300,L11.

Leadbeater,R.,Buil,C.,Garrel,T.,Gorodenski,S.,Hopkins,J.,Mauclaire,B.,Ribeiro,J.,Schanne,L.,Thizy,O.,andStencel,R.2011,Bull. Amer. Astron. Soc.,43,257.04.

Leadbeater,R.,andStencel,R.2010,arXiv:1003.3617v2(18March).Simbaddatabase.2011,eAurwebpage(http://simbad.u-strasbg.fr/simbad/sim-

id?Ident=epsaur).Stefanik,R.P.,Torres,G.,Lovegrove,J.,Pera,V.E.,Latham,D.W.,Zajac,J.,

andMazeh,T.2010,Astron. J.,139,1254.Stencel,R.2010,“EpsilonAurigaeinTotalEclipse2010,Mid-eclipsereport,”

Univ.DenverObs.(http://arxiv.org/pdf/1005.3738.pdf).Stencel,R.2011,privatecommunication(December7).

Table1.EquipmentinformationforobservationofeAur. Observer Telescope Spectro- Resolution Mean Spectral Number name graph* SNR range ( Å) of spectra C.Buil SCT0.28m 1 10,000 164 4500–7000 96 T.Garrel SCT0.21m 2 15,000 108 6500–6630 87 B.Mauclaire SCT0.30m 2 15,000 224 6520–6690 34 R.Leadbeater SCT0.20m 2 15,000 98 6500–6700 25 A.Lopez SCT0.28m 2 15,000 164 6500–6700 5*Spectrograph: 1) eShell; 2) Lhires3 2400 1/mm.


Figure1.eAurspectrumshowingHawingsoutofeclipsephase.Observationsof 12.881/12/2008, SCT 0.3m, Lhires3 2400 g/mm, 0.115 Å/pixel, B.Mauclaire,4×600s.

Table2.ContactdatesduringeAureclipse. Main contact MJD (day)

first 55070±3 second 55250±2 third 55630±2 fourth 55800±3

Table3.RadialvelocitymeasurementsofeAuratkeydates. MJD (day) Radial velocity (km/s)

55199.24 +19.46±1.54 55390.44 +14.79±1.37 55436.49 –38.10±1.54 55521.46 –60.36±1.54 55819.46 –31.59±1.54


Figure2.TimeevolutionofeAurfrom2455250.403to2455878.39.Hawingsareshownatkeydates.

Figure 3. Plot showing evolution with time of Equivalent Width computedbetweenl6550andl6577.NotethetwominimaatMJD55250±2and55630±2correspondingtosecondandthirdcontactsdates.


Figure 4. Light curve of e Aur using data from the AAVSO InternationalDatabaseshowingVmagnitudeevolutionwithintime.LightcurvecourtesyofAAVSO.

Figure5.SpectrumofeAur showingemissioncomponent atbottomofHaabsorption line. Observations of 12.939/7/2010, R. Leadbeater, TN 0.25m,Lhires32400g/mm,0.107Å/pixel.


Figure 6. Dynamical spectrum of Ha line from JD 2455120.605 to JD2455840.48. Interpolationbetween spectrawasused toget a smooth image.SinusoidallinesatbothHalineedgesaretelluriclineslyinginlineprofilesthatarecorrectedfromheliocentricvelocity.Theblackdashesalongtherightaxisshowtheactualobservationdates.

Leadbeateretal., JAAVSO Volume 40, 2012 729

High Cadence Measurement of Neutral Sodium and Potassium Absorption During the 2009–2011 Eclipse of ε Aurigae

Robin LeadbeaterThree Hills Observatory, The Birches, CA7 1JF, UK; address email correspondence to R. Leadbeater at [email protected]

Christian BuilCastanet Tolosan Observatory, 6 Place Clemence Isaure, 31320 Castanet Tolosan, France

Thierry GarrelObservatoire de Foncaude, Juvignac, France

Stanley A. Gorodenski9440 E. Newtown Avenue, Dewey, AZ 86327

Torsten HansenReichau 216, D-87737, Boos, Germany

Lothar SchanneObservatory for Stellar Spectroscopy Völklingen, Hohlstrasse 19, 66333, Völklingen, Germany

Robert E. StencelDepartment of Physics and Astronomy, University of Denver, 2112 East Wesley Avenue, Denver, CO 80208

Berthold StoberNelkenweg 14, 66791 Glan-Münchweiler, Germany

Olivier ThizyShelyak Instruments, Les Roussets, 38420 Revel, France

Received May 14, 2012; revised July 10, 2012; accepted July 10, 2012

Abstract TheresultsofaspectroscopicsurveyofeAurigaeduringeclipseusinganetworkofsmalltelescopesarepresented.Thespectrahavearesolutionof0.35to0.65Åandcovertheperiod2008to2012withatypicalintervaloffourdaysduringeclipse.ThispaperspecificallycoversvariationsintheKI7699Å,NaD,andMgII4481Ålines.AbsorptionstartedincreasingintheKI7699Ålinethreemonthsbeforetheeclipsebeganinopticalphotometryandhadnotreturnedtopre-eclipselevelsbytheendofthesurveyinMarch2012,sevenmonthsafterthebroadbandbrightnesshadreturnedtonormaloutsideeclipselevels.ThecontributionoftheeclipsingobjecttotheKI7699Ålinehasbeenisolatedandshowstheexcessabsorptionincreasinganddecreasinginaseriesofstepsduringeclipseingressandegress.Thisisinterpretedasanindication

Leadbeateretal., JAAVSO Volume 40, 2012730

ofstructurewithin theeclipsingobject.TheFstar is totallyobscuredby theeclipsingobjectattheNaDwavelengthduringeclipse.TheradialvelocityoftheFstarandthemeanandmaximumradialvelocityoftheeclipsingmaterialinfrontoftheFstaratanygiventimehavebeenisolatedandtrackedthroughouttheeclipse.Thequasi-periodicvariationsseenintheFstarradialvelocity(RV)outsideeclipsecontinuedduringtheeclipse.Itishopedthattheseresultscanbeusedtoconstrainproposedmodelsofthesystemanditscomponents.

1. Background

eAurigae is a naked eye eclipsing binary system with a period of 27.1yearsandaprimaryeclipseofabouttwoyears.Despitehavingbeenstudiedforalmosttwocenturies,ourunderstandingoftheexactnatureofthesystem,theprimarystar,anditslargelyunseencompanion,isstillincomplete. Ateacheclipse,anewgenerationofastronomersequippedwiththelatesttechnologytacklestheproblem.ArecentmultiwavelengthstudyofthesystemproposedthatthespectralclassFprimarystarismostlikelyanevolvedpost-AGBstarandthataB5Vclassstarisembeddedinthecool(~1000K)opaquematerialwhichcausestheeclipse(Hoardet al.2010,hereafterreferredtoastheHHSmodel). Interferometricmeasurementsmadeduring the2009–2011eclipsehaveestablishedthattheeclipsingobjectisanelongatedopaquecigarshapedobject,mostlikelyadiscseenalmostedgeon,whichcoversthesouthernhalfofthestarduringeclipse(Kloppenborget al.2010). Advances in sensor technology and the availability of affordable highresolutionspectrographsallowedanetworkofadvancedamateursusingsmallaperturetelescopestocontributeduringthe2009–2011eclipse.Theobjectivewas to study theevolutionof theoptical spectrumof the system throughouttheeclipsewithimprovedtimeresolutioncomparedwiththatachievedduringprevious eclipses. Over 800 spectra were collected and these are availableonline(http://www.threehillsobservatory.co.uk/epsaur_spectra.htm).

2. Observations

Thispaperspecificallycovers:

• 275observationsoftheneutralpotassiumlineat7699Å(hereafterreferredtoasK7699)atameanintervalof4.3daysthroughouttheeclipse.

• 199observationsoftheneutralsodiumDlinesat5890/5896Å(hereafterreferredtoasNaD)atameanintervalof4daysduringtheeclipse,excludingtheperiodsaroundsolarconjunction.

• 137observationsofthesinglyionizedmagnesiumlineat4481Å(hereafterreferredtoasMg4481).


TheobservationsaresummarizedinTable1.TheK7699lineobservationswere made by Leadbeater and Schanne at a resolution of 0.35Å usingLhires IIILittrowspectrographs,modified to reach thiswavelength.Variousspectrographdesignswithresolutionsfrom0.35–0.65ÅwereusedfortheNaDlineobservations.TheMg4481linemeasurementsweremadewiththeeShelechellespectrographsofBuil,Thizy,andGarrelattypically0.5Åresolution.

2.1.Choiceoflines Outside eclipse, the eAur spectrum shows an interstellar K7699 line(Welty and Hobbs 2001). There is no detectable contribution from the Fstar spectrum. This was confirmed by examining spectra outside eclipse(Lambert and Sawyer 1986;Welty and Hobbs 2001) recorded at differentphaseswhichshowednovariationinRVabovethelevelofthemeasurementuncertainty.IfastellarcomponentwaspresentitwouldbedetectableduetothechangeinRVofthatcomponent.Afterremovaloftheconstantinterstellarcomponent,theremainingK7699lineuniquelydescribestheabsorptionduetotheeclipsingcomponent.Spectraofthislinehadalsobeentakenduringthepreviouseclipse,thoughatlessfrequentintervals(LambertandSawyer1986). TheNaDlinesalsoshowstrongadditionalabsorptionduringeclipse(Barsony et al. 1986); however, the analysis of these lines is morecomplexduetothepresenceofcomponentsfromboththeFstarandtheinterstellarmedium. TheMg4481linearisesfromtheF-starphotosphereandisabsentfromthecooleclipsingobjectspectrumdue to thehighexcitation levelof theformer(FerlugaandHack1985),soactsasareferenceforchangesintheFstarRV.

2.2.Reductionofspectra The spectra were initially individually reduced by each observer (dark,flat, geometric corrections, cosmetics removal, background subtraction, andbinning).ExceptforStober,whosespectrawerenormalisedusingafittothecontinuum, the spectra were also corrected for instrument response using astandardstar.Noatmosphericextinctioncorrectionwasapplied.Fluxisrelativetothecontinuum.ThesoftwareusedbyeachobserverislistedinTable1. ThespectrawerethenfurtherreducedandlineparametersmeasuredbyRLusingvisual spec software.Thepre-reducedspectra foreach lineof interestwerefirstnormalizedusingafittothelocalcontinuum.Tomaximizetheglobalprecision of the NaD and K7699 line wavelength calibration, the originalcalibrationswerecheckedusingtelluriclinesvisibleinthespectraandsmalloffsetsappliedasrequired.TherearenotelluricsintheMg4481lineregionsotheobservers’originalThArlampcalibrationswereusedforthisline.Theestimatedresidualuncertaintyinwavelengthis0.02Å.Thetelluriclineswerethen removed, by dividing by hot line-free star spectra taken with the same


equipmentinthecaseoftheK7699linespectraorbyscalingastandardtelluriclinetemplateinthecaseoftheNaDlines.Finallythewavelengthsofallspectrawerecorrectedtotheheliocentricvelocityreferenceframe.

3. Analysis

For this paper, eclipse start and end dates of JD 2455070 and 2455800have been adopted based onV-band photometric data submitted toAAVSO(Mauclaireet al.2012).TheparametersusedforcalculatingthepropertiesofthesystemarelistedinTable2.

3.1.KI7699Åline Figure1 shows theevolutionof theK7699 line throughout theeclipse.Each row represents an interval of 2 days. The dates of the spectroscopicmeasurementsaremarkedonthetimeaxis.Intermediaterowsbetweenmeasuredspectraareinterpolated.Notethattheinterstellarcomponent(measuredfrompre-eclipsespectra)hasbeenremovedsotheplotshowsjustthecontributionfromtheeclipsingobject.Figures2and3showtypicalprofilesfortheK7699linewiththeinterstellarcomponentpresentandremoved,respectively. Figure4showsthevariationinthestrength(equivalentwidth,EW)oftheK7699lineincludingtheinterstellarcomponent,withmeasurementsfromtheprevious eclipse (Lambert and Sawyer 1986) superimposed for comparison.Figure 5 shows the same EWs for the K 7699 line with the interstellarcomponent removed. The estimated uncertainty in EW is 15mÅ, based onrepeat measurements and comparison with coincident observations made byotherobserversduringeclipseingress(Ketzeback2009). TheRVtrendfortheK7699lineafterremovaloftheinterstellarcomponentisshowninFigure6.ThemaximumvelocitycomponentinthematerialinfrontoftheFstaratanygiventimeduringingress(lineprofilerededge)andegress(lineprofileblueedge)isalsoplotted.

3.2.NaDlines Figure7showstheevolutionoftheNaDlinesthroughouttheeclipse.Eachrow represents an intervalof2days.Toproducea consistent setof spectra,higherresolutionspectrawerefilteredtogiveacommonresolutionof0.65Å.The dates of the spectroscopic measurements are marked on the time axis.Intermediaterowsbetweenmeasuredspectraareinterpolated.Figure8showstypical Na D2-line profiles throughout the eclipse, while Figure 9 shows aselection of full NaD-line profiles at a higher resolution of 0.35Å obtainedduringthesecondhalfoftheeclipse.ThetotalEWoftheNaDline(sumofD1andD2)asafunctionoftimebeforeandduringtheeclipseisplottedinFigure10. TheRVsoftheNaDlines(meanofD1andD2)andoftheMg4481lineasa functionof timebeforeandduring theeclipseareplotted inFigure11.


Alsoshownisa linearfit to theMg4481linedataand,forcomparison, theradialcomponentoftheorbitalvelocityoftheFstar(Stefaniket al.2010).

4. Discussion

4.1.Theextentoftheeclipsingobject Interferometric imaginghas shown thedrop inbrightnessduringeclipsetobeduetoanelongatedopaqueobject(athinrotatingdiscseenalmostedgeon)whichcoversthesouthernhalfoftheFstar(Kloppenborget al.2010).Thechangesweseeinthespectrumduringeclipsearisefromabsorptionwithinagaseousregionsurroundingthisopaqueobject.Increasedabsorptionwasfirstdetectedin theK7699line95daysbeforephotometricfirstcontactandwasstilldetectableattheendofthesurvey,215daysafterfourthcontact.Adoptingascaleof3.8AUfortheradiusofthediscaspertheHHSmodel,weestimatethatthisgaseousregionextendsbeyondtheouteredgesoftheopaqueregionby1.2AUontheingresssideandatleast2.6AUontheegressside. OutsideeclipsetheNaDlines,acombinationofcontributionsfromtheFstarandtheinterstellarmedium,arenotfullysaturated.Duringeclipse,however,the lines saturate and the residual flux in the coreof the lines falls close tozero.This is seenparticularlyclearly in thehigher resolution spectra showninFigure9takenduringthesecondhalfoftheeclipse,inwhichtheeclipsingdisccomponentoftheline,blue-shiftedduringthishalfoftheeclipse,showsadistinctlyflattenedbottomatjust0.03ofthefluxrelativetothecontinuum.GiventhattheopaqueregioneclipsesonlythesouthernhalfoftheFstar(asseenintheinterferometricimages)thissuggeststhattheNa-absorbingregionextendsatleasttheF-starradius(0.6AU)abovetheopaqueregion,completelycoveringtheFstar. Asmallpeakisvisible,~10km/sbluewardsoftherestwavelength,inthehigh resolution NaD absorption lines during the second half of the eclipse(Figure9).Thiswasalsoobservedduringthepreviouseclipse(Barsonyet al.1986).Itislikelythatthisisduetoapartialseparationoftheeclipsingdisc/F-star components (bothblue-shiftedduring thishalfof theeclipse) and theinterstellarcomponent.Thesameeffect isseen in theK7699 linewhere theseparationofthetwocomponentsisclear(Figure2). The EW of the Na D lines at the end of the campaign period was stillsignificantly higher than pre-eclipse values (p << 0.001, mean 2.20Å range2.18–2.24,8valuesRJD55954–56005asopposedtomean1.79Årange1.67–1.86,6valuesRJD54455–54779);however,thiscouldbedueatleastinparttotherelativeseparationofthecomponents.(Becausethelineissaturated,theEWwilldependontheoverlapbetweenthecomponentswhich,inturn,dependsontherelativeRV).Extendedpost-eclipsemonitoringcouldhelpclarifythis. TheEWofboththeK7699andNaDlinesdroppedaroundmid-eclipse.InthecaseofthesaturatedNaDlinethiscouldbecaused,forexample,bya


narrowingofthealreadysaturatedlineprofileratherthananetreductionintheamountofabsorbingmaterial.ThiswouldnotbethecasefortheunsaturatedK7699line,however,andsuggeststhateitherthereislessabsorbingmaterialintheseinnerregionsofthediscorthattheconditionsclosertothecentralstardonotallowtheparticulartransition(duetoradiationfromthecentralstar,forexample).The intervalbetween the leadingand trailingEWmaxima for theK7699lineis265days,whichcorrespondstoaregion2.1AUindiameter. ThereissignificantasymmetryintheK7699lineexcessabsorptionbetweentheleadingandtrailingregionsofthedisc.Thetrailingmaximumis70%higherthantheleadingmaximum(780mÅasopposedto460mÅ,seeFigure5).Asalreadymentioned, the tailof theabsorptionextendssignificantly furtherontheegressside.Thelateralextentofthemainregionofabsorption,however,issimilarforbothhalves(200daysfrom30%tomaximumabsorptionduringingresscomparedwith220daysduringegress). TheminimumfluxintheK7699lineprofileremainedsignificantlyabovezeroduringtheeclipse(theminimumlevelwas0.18relativetothecontinuum)so,providedthatthematerialproducingthislineextendsabovethedisctothesameextentasthatfortheNaDline,coveringtheFstarcompletely,wecanconcludethatwhenwelookattheK7699lineweareseeingthroughthefullthicknessofthematerialand,therefore,thelineprofileincludescontributionsfromalldepthswithintheabsorbingregioninfrontoftheFstaratthetime.

4.2.Comparisonwiththepreviouseclipse ThereisgoodoverallagreementbetweenthetotalK7699lineEWtrendduring this eclipse andmeasurementsmadebyLambert andSawyeron thislineduringthepreviouseclipse,offsetby9,896days.ThelargestdifferencesoccuratRJD55340and55615butLambertandSawyerplottedasmoothcurvethroughtheirmoresparsedataandattributedtheresidualscattertomeasurementerror,soitisnotclearifthesedifferencesaresignificant.

4.3.Structurewithinthedisc The trendof excessK7699absorptionduring eclipse (Figure5)didnotprogresssmoothlyduringingressandegressbutproceededinaseriesofsteps.Thestepsduringingresshavebeeninterpretedasanindicationofstructurewithinthediscmaterial(LeadbeaterandStencel2010).Thereisnoobvioussymmetryinthesefeaturesbetweeningressandegress,asmightbeexpectedforasimplesystemofconcentriccircularrings,thoughmorecomplexstructuressuchasanellipticalsystemorspiraldensitywavesproducedbythetidalinfluenceoftheFstar,asseeninothercircumstellardiscs(forexample,Mutoet al.2012),arenotruledout.(NotethatfeaturesarealsoseenintheNaDlinetotalEWtrendbutthesedonotcorrespondwiththestepsseenintheK7699EWandmaybecausedbyinteractionsbetweenthevariouscomponentswhichmakeuptheline.Theseinteractionsarediscussedinsection4.5.)


4.4.Thediscrotation ThetrendoftheK7699lineRVafterremovaloftheinterstellarcomponent(Figure 6) is smooth throughout the eclipse with little scatter (except at thestartandendofeclipsewhenthelineisweak)andnoobviousshorttimescalefeatures.Giventheknownquasi-periodicvariabilityseenintheRVoftheF-starlines(Stefaniket al.2010),thisisadditionalconfirmationthattheK7699lineisnotsignificantlycontaminatedbyanycontributionfromtheFstar.Sincewe are seeing through the full depth of the disc at this wavelength, the RVvaluesplottedhereareameasureofthemeanvelocityalongourlineofsightofallthevectorsoftheorbitingcomponentsoftheabsorbingmaterialinfrontoftheFstarataparticularphaseoftheeclipse.Whileitmayprovepossibletomodelsuchaparametergivenadetaileddescriptionof thepropertiesanddistributionofthematerialsurroundingthedisc,aperhapssimplerparameter,themaximumvelocitycomponentintheline,hasalsobeenplottedinFigure6.This is somewhat more difficult to measure as it involves estimating thewavelengthof theedgeof thelinewhereitmeets thecontinuum,andthis isreflected in the increasedscatter. Ithas thepotential,however, tobeused tocalculateanorbitalvelocitycurveforthediscsince,formaterialinKeplerianorbits,themaximumradialvelocityatagiventimewillbeduetotheinnermostmaterialinfrontoftheFstaratthattimeviewedtangentiallyand,hence,givesa direct measurement of the orbital speed of that material.This has alreadybeenattemptedusingthedatafromthefirsthalfoftheeclipse(LeadbeaterandStencel2010)wherea figureof5.3 solarmasseswasestimated for thedisccomponent.However,thisvalueissensitivetotheRVadoptedfortheeclipsingcomponentasawholeduetoitsorbitalmotion,whichisnotknowncurrently.We speculate that this orbital motion is, at least in part, responsible for theasymmetryseenintheRVcurvefromingresstoegress,(highervaluesofRVseenonegressandadecliningRVinthelaterpartoftheeclipsecomparedwiththelevelRVduringingress);however,afullorbitalsolutionforthesystemwillbeneededtoclarifythis.

4.5.TheradialvelocityoftheNaDandMg4481lines TheNaDlinesareacombinationofcomponentsfromtheeclipsingdisc,the interstellar medium, and the F star. The interstellar component will beconstantasfortheK7699linebuttheFstarRVwillhaveanorbitalcomponentandquasi-periodicvariations(Stefaniket al.2010).Thenetresult(Figure11),althoughbroadlyshowingthesameswingfromredtoblueduringeclipse,isquite different in detail from that of the disc component extracted from theK7699line. NotenoughisknowncurrentlyabouttheinterstellarorF-starcomponentsto allow the net effect of the eclipsing disc to be isolated in the NaD line.This might be possible in the future using more data obtained outside ofeclipse. (Throughout the orbit, the NaD line F-star component will move


independentlyoftheinterstellarcomponentsoitshouldbepossibletoisolatethetwocomponents.)TheNaDlinealsobecomessaturatedduringtheeclipsesothelineprofileisnotasimplelinearcombinationofthethreecomponents.Nonetheless,wecanmakesomequalitativeobservations. TheMg4481lineisproducedbytheFstaronly(FerlugaandHack1985)sotheRVofthislinecanbeusedasareferencefortheF-starNaDcomponentRVduringeclipse.TheMg4481linedataclearlyshowthatthequasi-periodicvariationsinFstarRVseenoutsideeclipsecontinuedduringtheeclipse.NoteinFigure11thattheNaD-lineRVfollowsthesevariationsintheintervalRJD55080–55150.Thedisccomponentthenstartstodominate,rapidlyincreasingthe RV to approximately +16 km/s before reversing through mid eclipseto approximately –23 km/s. There is again some correlation between Na DandMg4481RV in the intervalRJD55570–55700, but thedisc absorptionstronglysaturatestheNaDlinesduringthisperiodsothesensitivitytotheF-starvariationsisexpectedtobelow.ByaboutRJD55800theRVhadreturnedclosetotheFstarRVasmeasuredbytheMg4481line.

5. Further work

Additionalspectratakenoutsideeclipseareneededtodeterminetheextentoftheabsorptionduetotheeclipsingdiscontheegresssideandtoseparatetheinterstellar,F-star,andeclipsingdisccomponentsintheNaDlines. Theechelle spectrausedhere tostudy theNaDandMg4481 linesalsocovermanyother linesknown to showchangesduringeclipse (FerlugaandHack 1985).A similar analysis of these lines may reveal more informationaboutthestructureandconditionswithintheeclipsingdisc.

6. Acknowledgements

WearegratefultoJeffHopkinsfororganizingtheInternationalCampaignfor the observation of eAur during this eclipse and to all who submittedobservations. We thank the eAur spectral monitoring team atApache PointObservatory(W.Ketzeback,J.Barentine,et al.)forallowingusaccesstotheirK7699linedataduringingress.WeacknowledgewiththanksthevariablestarobservationsfromtheAAVSOInternationalDatabasecontributedbyobserversworldwide and used in this research. R.E.S. is grateful for the bequest ofWilliamHerschelWombletotheUniversityofDenverinsupportofastronomy,andforsupportunderNationalScienceFoundationgrant#AST1016678totheUniversityofDenver.


References

Barsony,M.,Mould,J.R.,andLutz,B.L.1986,Publ. Astron. Soc. Pacific,98,637.Ferluga,S.,andHack,M.1985,Astron. Astrophys.,144,395.Hoard,D.W.,Howell,S.B.,andStencel,R.E.2010,Astrophys. J.,714,549.Ketzeback,B.2009,privatecommunication,ApachePointObservatory.Kloppenborg,B.,et al.2010,Nature,464,870.Lambert,D.,andSawyer,S.1986,Publ. Astron. Soc. Pacific,98,389.Leadbeater,R.,andStencel,R.2010,arXiv:1003.3617v2[astro-ph.SR].Mauclaire,B.,et al.2012,J. Amer. Assoc. Var. Star Obs.,40,718.Muto,T.,et al.2012,Astrophys. J., Lett. Ed.,748,L22.Parthasarathy,M.,andFrueh,M.L.1986,Astrophys. Space Sci.,123,31.Stefanik,R.P.,Torres,G.,Lovegrove,J.,Pera,V.E.,Latham,D.W.,Zajac,J.,

andMazeh,T.2010,Astron. J.,139,1254.Welty,D.,andHobbs,L.2001,Astrophys. J., Suppl. Ser.,133,345.

Table1.Summaryofobservations.

Observer Aperture Spectrograph Reduction Number of (mm) Software* Observations K 7699 Na D Mg 4481

Buil 280 eShel** 4 — 96 94 Garrel 280 LhiresIII*** 1,2 4 eShel 4 — 24 24 Gorodenski 405 LhiresIII 1,2 26 — Hansen 280 LhiresIII 1,2 — 4 — Leadbeater 200/280 LhiresIII 1,2 259 12 — Schanne 355 LhiresIII 3 16 6 — Stober 300 customechelle 3 — 8 — Thizy 280 eShel 4 — 19 19

TOTAL 275 199 137*Reduction Software: (1) IRIS (www.astrosurf.com/buil/us/iris/iris.htm); (2) Visual Spec (www.astrosurf.com/vdesnoux/); (3) ESO-MIDAS (www.eso.org/sci/software/esomidas/); (4) AudeLA-ReShel (http://www.audela.org).

**eShel (www.shelyak.com/dossier.php?id_dossier=47).***Lhires III (www.shelyak.com/dossier.php?id_dossier=46).

Table2.Adoptedsystemparameters. Parameter Value Reference

discradius 3.8AU Hoardet al.2010 Fstarradius 135R

Ä Hoardet al.2010

meaneclipseduration 710days ParthasarathyandFrueh1986


Figure1.PlotshowingtheevolutionoftheK7699lineafterremovaloftheinterstellarcomponent(darkercolorssignifyincreasedabsorption).Tickmarksontheright-handy-axisindicateactualmeasurements.Intermediaterowsareinterpolated.

Figure2.AselectionoftypicalK7699-lineprofileswiththeinterstellarcomponentincluded.

Figure3.AselectionoftypicalK7699-lineprofileswiththeinterstellarcomponentremovedbasedonpre-eclipsemeasurements.


Figure 4. K7699-line total equivalent width (including the interstellarcomponent)comparedwith1983eclipsedatashiftedintimeby+9,896days.

Figure 5. K7699 excess equivalent width after removal of the interstellarcomponent.Thetrendlineindicatesthestepwiseprogression.


Figure6.RadialvelocityoftheK7699line(heliocentric).Thered(ingress)andblue(egress)edgevaluesarethemaximumabsoluteRVinthelineprofile.

Figure7.PlotshowingtheevolutionoftheNaDlines(darkercolorssignifyincreased absorption). Tick marks on the right-hand y-axis indicate actualmeasurements. Intermediate rows are interpolated.The gaps are the periodsaroundsolarconjunction.


Figure8.AselectionoftypicalprofilesfortheNaD2lineat0.65Åresolution.

Figure 9.A selection of NaD-line profiles covering the second half of theeclipseat0.35Åresolution.


Figure 11. Radial velocity of the NaD lines (mean of both lines) and theMg4481line.AlinearfittotheMg4481linedataandtheF-starRV(basedonStefaniket al.2010)arealsoshown.Allvelocitiesareheliocentric.

Figure 10. NaD-line equivalent width (sum of both line components) as afunctionoftimebeforeandduringeclipse.

Gorodenski, JAAVSO Volume 40, 2012 743

Spectroscopic Results From Blue Hills Observatory of the 2009–2011 Eclipse of e Aurigae

Stanley A. Gorodenski9440 East Newtown Avenue, Dewey, AZ 86327; [email protected]

Received February 7, 2012; revised February 17, 2012; accepted February 28, 2012

Abstract The purpose of this paper is to report spectroscopic results ofeAurigaeduringthe2009–2011eclipse.SpectraofthesodiumDlinesandanabsorptionlineoccurringatapproximately5853ÅweretakenfromFebruary13,2010,toOctober10,2011,withanLHIRESIIIspectrographanda16-inchMeadetelescopeatBlueHillsObservatoryinDewey,Arizona.Equivalentwidthandradialvelocitydatasupportthepresenceofavoidorringstructurewithintheeclipsingdisk,andtheysupportacentraldiskclearingaroundanunseenprimarycentralobject.Theresultsalsoindicatethediskdoesnotendatfourthcontact but continues for a significant distance.Analysis of radial velocitiesdemonstratedtheprofileofthe5853ÅlinehasadiskcomponentinadditiontotheprimaryF0starcomponent.Asplitlineatthislocationwasobserved.Fromtheequivalentwidthprofileofthe5853Ålinethedurationofthesplitlineeventwasestimatedtobe101days.Otherlesserresultsarepresentedanddiscussed.

1. Introduction

eAurigaeisaneclipsingbinarysystemwithaperiodof27.1yearsandaneclipsethatlastsalmosttwoyears.TheprimarystarisanF0staralthoughrecentworkindicatesitmaybeahighlyevolvedobject(Leadbeater2011).TheeclipseisthoughttobecausedbyadiskofdustrotatingaroundanunseencentralobjectwhichisinorbitaroundtheprimaryF0star.Thelasteclipseandcampaignwas1982–1984.Forthe2009–2011eclipseaninternationalcampaignwasorganizedbyDr.RobertE.StencelandJeffreyL.Hopkins.Thereisamajordifferencebetweenthiscampaignandthepreviousone.Alotoftheamateurcontributiontothepreviouscampaignwasintheformofelectronicphotometry.SincethenarangeofhighperformanceCCDcamerashavebecomeavailabletotheamateur,aswellasrelativelyinexpensivehighresolutionspectrographssuchasSBIG’sSGS spectrograph and Shelyak’s LHIRES III and eShel spectrographs. TheauthorownsanLHIRESIIIspectrographwitharesolutiongreaterthan18,000.At the encouragement of Jeff Hopkins, the author worked on the sodium Dabsorptionlinesforthiscampaign. This paper consists primarily of observations and analyses with somediscussionandinterpretation.AlthoughthesodiumDabsorptionlinesfromthediskareconfoundedwithabsorptionlinesfromtheprimaryF0star,noattemptwasmadetosubtracttheF0contributionfromthespectra.Doingsorequiresan

Gorodenski, JAAVSO Volume 40, 2012744

out-of-eclipseestimateoftheF0absorptionlines.Thiscanbedone,butusingitrequiresonetoassumetheF0radialvelocitiesandequivalentwidthsdonotchangeduringtheeclipse.Theauthorprefersnottomakethisassumptionandsoanout-of-eclipsecomponentwasnotsubtracted.Becausesuchasubtractionwould have involved a constant component in any event, it is felt one canstill obtain meaningful results and interpretations. In addition to the sodiumD lines, this paper also includes a line located at approximately 5853Å.Anevaluationofanout-of-eclipsespectrumtakeninJuly2008byOlivierThizyhasnotbeensuccessful in identifyingthis line.Onepossibility isBariumII.(Theprofileis20080727-031309-epsAur-5x300s_P_1C_FULL.fitandisfoundattheeAurspectraldatabasemaintainedbyRobinLeadbeaterathttp://www.threehillsobservatory.co.uk/astro/epsaur_campaign/epsaur_campaign_spectra_table.htm.)Inlieuofadefiniteidentification,itwillbereferredtoasthe5853Ålineinthispaper.Itexhibitsanunexpectedlinesplitwhichwillbediscussed. Thesodiumdoubletconsistsoftwolines,D2 (λ = 5889.95Å) and D1 (λ = 5895.924Å).Figure1isatypicalspectrum,normalized,ofthesodiumDlinesregion, about 175 Ångstroms wide, taken on February 26, 2010. Figure2contains profile examples to illustrate the evolution of the D lines. It alsoillustratestheresolutioncapabilitiesoftheLHIRESIIIspectrograph. The data contained inTables 1, 2, 3, and 4, are available for downloadfrom theAAVSO ftp site at ftp://ftp.aavso.org/public/datasets/jgoros402a.txt,jgoros402b.txt,jgoros402c.txt,andjgoros402d.txt.

2. Instrumentation and methods

Theworkwasconductedattheauthor’spersonalobservatory,BlueHillsObservatory(http://users.commspeed.net/stanlep/homepagens.html),locatedinDewey,Arizona.TheequipmentconsistedofaMeade16-inchLX200Rtelescope(vintage2006),theLHIRESIIIspectrograph,anST8-XMEcameraforimagingthe spectra, and a Meade DSI I camera for guiding.The spectrograph’s slitwidthwassetat22-microns,whichenabledthespectrographtoobtainhigherresolutionspectrathanpossiblewiththewiderwidth,usuallyaround30to35microns,normallyusedbyownersoftheLHIRES.Variousguidingsoftwarewas tried and tested.The major ones used were Meade’s envisage and phd.ccdsoftcapturedtheimages,iris(version5.57)wasusedtoreducethespectra,and vspec and audela were used to calibrate and do additional processing.Greatcarewastakentoobtainverygoodcalibrationsusingtelluriclines.Aftercalibrationthetelluriclineswereremoved(usingvspec)andthespectrawerethenheliocentriccorrected.Afterallthisprocessing,thereducedspectrawereanalyzedusingspss,astatisticalsoftwarepackage.Thegraphsandtablesinthispaperwereproducedwithspss. Table1givesthedatesthespectraweretaken.Becauseoftheshortintegrationtime—onlytenminutes—manytimesmorethanonespectrumpernightwere


obtained.The result was a total of seventy spectra over the time period theauthorparticipatedinthecampaign.Thedatapointsoftheseadditionalspectrapernightcanbeseeninthegraphsinthispaper.

3. Equivalent width

Equivalent width (EW) was estimated using the method described byGorodenski (2011).With this method a continuum is estimated with a leastsquarespolynomialregressionmodel.Thebeginningandendpointsofalinefor thepurposeofcomputinganEWaredefinedwhere the line is judgedtocome in contact with, or cross through, the estimated continuum.At timesduring theevolutionof theNaD lines, themidpointbetween theD2andD1linesdropsbelowtheestimatedcontinuum.WhenthishappenedthecrossoverpointsforestimatingtheequivalentwidthsweretakentobemidwaybetweentheDlines. Table1hastheequivalentwidths(inÅngstroms)and95%upperandlowerconfidencelimitsfortheNaDlinesandthe5853Åline.Figures3and4areplotsoftheequivalentwidthsoftheNaD2andNaD1lines,respectively. TheestimatedcontactdatesoftheeclipseinBbandfromHopkins(2012)are:

1stContact August11,2009 JD2455054 2ndContact December19,2009 JD2455184 Mid-Eclipse August4,2010 JD2455412 3rdContact March19,2011 JD2455639 4thContact May13,2011 JD2455694

Theapplicabledates(thelastthree)areshowninallthegraphsinthispaper. Thediskinclinationhasbeenreportedtobenearlyedgeon(HopkinsandStencel2008)andatmost90°±2°(Kloppenborg2012).As thediskmovesacross(eclipses)thestar,theamountofdiskmaterialcontributingtoaspectrumshould be at a minimum at mid-eclipse, gradually increase to a maximumat third contact, and after third contact it should decline. One would expectequivalentwidthstoconformtothesechangingamountsofdiskmaterial.TheprofileoftheequivalentwidthsinFigures3and4generallyagreeswiththeseexpectations.Theequivalentwidthsareatalowpoint(althoughnotthelowestaswillbeshortlydiscussed)atmid-eclipse,andtheygraduallyincreaseaftermid-eclipseuntil they reachahighpointat thirdcontact.After thirdcontacttheyexhibitadeclineasexpected.However, thedeclineappears tocontinuewellafterfourthcontact(150daysbeyondfourthcontact)whentheprimaryF0starshouldbefarclearofthedisk.Therelativelyconstantslopeofthedeclinefor150daysafter the star reached fourthcontact indicates thediskmaterialdoesnotabruptlyendatthispoint,butgraduallydisappears. There are a few irregularities in the graphs that appear to be real, thatis, theyarenotasamplingerrororaproblemwith thedata.One isadipat


approximatelyJanuary16,2011.Theauthorinterpretsthisasavariationintheamountofdiskmaterial,meaningthediskmaterialisnotdistributeduniformlyacrossthediskandmaybepatchyorclumpy.ThisagreeswithLeadbeateret al.(2011)whointerpretstructurewithinthediskasbeingresponsiblefortherateofincreaseofEWduringingress. Theotheranomaly,amajorone,isatthebeginningoftheseries.Theseries(profile)ofequivalentwidthsstartatasignificantlylowerlevel thanatmid-eclipse.There isadefinite increasing trend thatstarts fromthebeginningofthe series and peaks on March 28, 2010. (Based on the author’s experiencewithregressionanalysis,astatisticallysignificantpolynomialregressionmodelwouldfitthispartoftheseries.Itshouldbeobvioustothereaderthatthistrendisnotrandomerror.)ThisanomalyoverthesametimeperiodisalsoseenintheradialvelocitygraphsofD2andD1inFigures6and7,respectively,inthesectiontofollowonradialvelocities. TheEWandradialvelocitydatatogetherareevidenceofaringstructuretothedisk(LeadbeaterandStencel2010;Seebodeet al.2011),oralargevoidinthedisk(theauthor’shypothesis).Ifaringgaporvoidexists,therewouldbelessmaterialcontributingtoalinestrengthand,hence,theequivalentwidthwouldbesmallerinvalue.AsthediskmovesfromfirstcontacttothepointwheretheprimaryF0starjustclearstheinnerboundaryofthedisk,radialvelocitiesshouldincrease, not drop, according to Kepler’s Law of Planetary Motion.A largevoidorringgapexplainsthedropinradialvelocitiesforthefollowingreason.Becausetherewouldbenodiskmaterialinthisspacetherewouldbenodiskmaterialmovinginaradialdirectionawayfromtheobserver(theradialvelocityvaluesarepositiveandsothemovementwouldbeawayfromtheobserver).Thecontributiontotheobservedradialvelocitiesthencanonlycomefromthepartsofthediskoneithersideofthevoid.Whattheobserverseesistheradialcomponent(theothercomponentisthepropermotioncomponent)ofthediskasitrotates.Thisradialcomponenthasasmallervelocityvaluethanmaterialmoving directly away from the observer would have at the location of thehypothesizedvoidorringgap.AsthevoidorgapmovesacrosstheprimaryF0star,radialvelocitiesstartincreasingasdustmaterialmovesintothelineofsight. Figure5isagraphofthe5853Ålineequivalentwidths.ItcanbeseenthattheEWprofile ismuchmorevariable.However,a secondorderpolynomialregressionmodel,showninthegraph,wasstatisticallysignificantatthe0.001level,indicatingthe5853ÅlineprofilegenerallyfollowsthesametrendastheNaDlines.(AsecondorderpolynomialwasstatisticallysignificantforbothDlinesandinthesamedirectionasthe5853Åpolynomialbutisnotdisplayedinthegraphsbecauseofaconcernoftoomuchgraphclutter.)Thelargedropthatbottomsoutbetweenthirdandfourthcontactcanbeexplainedbyasplitlinewhichwillbediscussedlater.


4. Radial velocity and the 5853Å split line

An estimate of radial velocity requires an estimate of the center of aspectralline.Fourdifferentkindsofestimatesweremadewiththeassistanceofvspec.Theyfallintotwomajorcategories:EWversusVisual.EWmeansthat thebeginning and endpoints of a line for line center estimationwerethesamebeginningandendpoints thatwereused forestimating the line’sequivalentwidth(usingthemethoddescribedinGorodenski2011).BecauseofthefrequentoccurrenceofalongwingonthebluesideoftheD2line,itwasfeltthismethodmightnotgivegoodlinecenterestimates.Therefore,aseparatesetofestimateswasmadebasedonavisual“guess”ofthebeginningand end points of the lines in vspec. An attempt was made to minimizeinclusionofasymmetriclongwings.AlthoughthisVisualestimateisdifficulttodefine,anattemptwasmadetobeasconsistentfromspectrumtospectrumasmuchaspossible. Withineachofthesetwocategories,thatis,EWandVisual,twokindsoflineestimateswereperformed in vspec.Onewasabarycenter lineestimate,whichwillbecalled“Barycenter,”producedbycheckingaboxinvspeccalled“LineCenter.”Theotherisa“Gaussianfit”estimate.However,vspecusestheline location of the barycenter of the Gaussian fitted line as the line center,thatis,thelinecenterestimateisnottheestimatedparameteroftheGaussianfunction.However,itwillstillbecalledthe“Gaussian”estimate. ThelinecenterestimatesofeachofthesodiumDlinesconsistedofthefourtypesjustdescribed.However,the5853ÅlineismuchweakerthantheDlines.Becauseofthisitwasfeltgettinga“Visual”estimateforthe5853Ålinewouldhavebeenverydifficult,maybeimpossibletoconsistentlyestimate.Asaresult,thebeginningandendpointsforestimatingalinewerethebeginningandendpoints thatwereused to estimate the equivalentwidths.Consequently, therewereonlytwoestimates(incontrasttothefourfortheDlines),theBarycenterandtheGaussianestimates. Adecisionhadtobemadeastowhichofthefourestimatesforsodiumandthetwoforthe5853Ålinearethebestforcomputingradialvelocities.Todothisastandarddeviationwascomputedforeachofthelineestimationmethodsforeachelementline.Table2containsthesestandarddeviations.Forthe5853ÅlinetheBarycenterestimateshavealowerstandarddeviationthantheGaussianestimates.Hence,theBarycenterestimateswereusedforcomputingthe5853Åradialvelocities.ForbothsodiumDlinesthe“Visual”estimateshavesmallerstandarddeviationsthanthe“EW”estimates.Within“Visual,”theBarycenterestimateshavesmallerstandarddeviations.Hence,fortheDlinestheVisual-Barycenterestimateswereusedtocomputeradialvelocities.Table3containsthe line center estimates for all three lines. Table 3 also contains a vspecestimateofthelinecentersofthe5853Asplitline,thesplitlinementionedintheintroductionofthispaper.


Table4containstheradialVelocities(km/sec)forNaD2,NaD1,5853Å,andthe5853Åsplitline.Byconvention,apositivevalueindicatesaredDopplershift, that is, theobject ismovingawayfromtheobserver.AnegativevaluemeansablueDopplershift,oranobjectmovingtowardtheobserver. Figures 6 and 7 are plots of the radial velocities for Na D2 and Na D1,respectively, with a statistically significant (0.001) 2nd order polynomialregressionlineforeach.Thereareanumberofthingstonotice.First,atmid-eclipse it is expected that the radial velocity should be equal to zero. Thehorizontalsolidlineisthezeroradialvelocityline.TheestimatedpointswheretheinterpolatedNaD2andNaD1linescrossthehorizontalzeroradialvelocitylineareAugust8,2010,andAugust4,2010,respectively. However,thesearenotmid-eclipseestimatesbecausetheeAursystemismovingtowardEarthatabout2.5km/sec,±0.9km/sec.Consequently,whatmightbearedshiftradialvelocityof2.5km/secwitheAurastheframeofreferencewillappearasazerokm/secradialvelocityfromEarth,thatis,withEarthastheframeofreference.Therefore,2.5km/sechastobeaddedtotheradialvelocitiesinthispapertoconverttotheeAurframeofreference.Whenthisisdone,theauthor’sdatasuggestthemid-eclipsedatesforNaD2andNaD1areAugust18,2010,andAugust16,2010,respectively.BecausethereisnoquantumexplanationthatcouldallowtheDlinetohavedifferentmid-eclipsedates, these dates can be taken as independent estimates of the actual mid-eclipsedate.Averagingthetwogivesanestimatedmid-eclipsedateofAugust17,2010. TheincreasingradialvelocitiesfromthebeginningoftheseriestoMarch28,2010,havealreadybeenexplainedasbeingduetoapossibleringgap,orapossiblevoidinthedisk. TheradialvelocitycurvefromaboutMay6,2010,toaboutNovember1,2010,inbothFigures6and7supportsthehypothesisthatthediskhasacentralclearareaaroundanunseencentralobject.Inotherwords,thediskhasanouterand inner edge, or boundary. Based on this hypothesis, one would expect adecreasingradialvelocityfromMarch28,2010(assumingthispartofthecurveisatorneartheinnerboundaryontheingresssideofthedisk)tomid-eclipseandthenanincreasingonefrommid-eclipsetoNovember1,2010(assumingthis part of the curve is at or near the inner boundary on the egress side ofthedisk)andthisiswhatisobserved.Theexplanationforthisexpectationisthesameastheonegiventoexplainthedropinradialvelocitiesintheabovesectiononequivalentwidth.Essentially,withoutcentraldust, theobserverisseeingthediskonbothsidesofthevoid.Asaresult,whatisbeingobservedistheradialcomponent(theothercomponentbeingthepropermotioncomponent)totherotationalmotionofthedisk.Asthemid-eclipseisapproachedthisradialcomponentbecomessmaller,eventuallygoingtozero.Thereverseoccursontheothersideofmid-eclipse.Thisexplainstheshapeanddirectionofthelinebetweenthesedates.


AscanbeseeninFigures6and7,theradialvelocitiesstillhavenotreachedthezeroradialvelocitylevelafter4thcontact.ThelastdatapointinthegraphisOctober10,2011.Thisis150dayspastfourthcontact.BythistimetheprimaryF0starshouldbewellclearofthedisk.Yet,radialvelocitiesonthisdateareover8km/sec(seeTable4).ThisisadditionalevidenceinsupportoftheEWdatathatthediskcontinueswellbeyondfourthcontact. Figure8 is theradialvelocityplot for the5853Åline. It isof interest todeterminewhetherthislineisundergoingthesameradialvelocitychangeastheNaDlines.Ifitis,thenthiswouldbeevidencethereisadiskcomponenttothe5853Åabsorptionline.ThesecondorderpolynomialsinFigures6and7fortheDlinesarestatisticallysignificant(0.001).Althoughthe5853ÅradialvelocitiesexhibitmorevariabilitythanthoseoftheNaDlines,astatisticallysignificant(0.001)secondorderpolynomialmodelalsofitsthedataandisinthesamedirectionastheDlinespolynomials.Thisisevidencethatthereisadiskcomponenttothe5853Åabsorptionline.However,thisisnotcertain.ItcouldallstillbefromtheprimaryF0star. There isonebigdifference in the5853Ålineprofilecompared to theDlines.StartingjustafterJanuary27,2011,the5853Åradialvelocitiesundergoa largeblueshiftdropandreachahighof28.866km/seconApril13,2011(spectrumnumber1inTable4).TheNaDlinesdonotexhibitsuchadrop.ThelargestblueshiftfortheD2andD1lineswere23.842km/secand23.843km/sec,respectively,onJanuary17,2011(spectrumnumber1inTable4). Thelargedropinthe5853Åradialvelocitiesiscausedbytheconfoundingeffectofthe5853Åsplitline.Figure9isagraphofthesplitlineradialvelocitieswith a superimposed statistically significant (0.001) first order polynomialregressionline.ItcanbeseenthesplitlineradialvelocitieshadalreadystarteddroppingonJanuary17,2011,andreachedahighblueshiftof27.954km/seconApril26,2011(spectrumnumber1inTable4).Thesedatesdonotexactlymatch those for the5853Å linebut areclose.Thereare two reasons for theinexactmatch:thesplitlinedataisveryincomplete,andthelinecenterscouldonlyberoughlyestimatedinvspec.Figure10showstheevolutionofthesplitlineandillustratessomeofthedifficultiesofgettinglinecenterestimates.Theprofile on December 25, 2010, was included to demonstrate the latter. Thisprofileexhibitswhatmightbecalledaplateau,notawelldefinedlinesuchastheoneonMarch28,2010. Suchaplateaumakesitimpossibletoestimateasplitlinecenter.Inaddition,therewereundoubtedly5853ÅspectrathatcontainedtheeffectsofasplitlineonEWandradialvelocity,buttheeffectwastoosmalltobenoticeableinalineprofile. Thestartandenddatesofthesplitlinephenomenoncannotbedeterminedfrom the split line data itself, but it appears a reasonable estimate might beobtained fromFigure5, thegraphof the5853Åequivalentwidths.AvisualinspectionofthegraphplacesthestartandendofthesplitlineatJanuary27,


2011,andMay8,2011,respectively,whichgivesadurationof101days.Kim(2008)reportsa67-dayanda123-dayperiod,althoughitisnotclearwhattheseperiodsrepresent,thatis,whattheyareperiodsof.

5. Conclusion

Thispaperhasdemonstrated thehigh resolutionspectroscopicwork thatcanbedonewiththeLHIRESIIIspectrograph.Thepaperalsodemonstratedthefollowing:

1. TheprofileoftheequivalentwidthsfortheNaDlinesgenerallyagreewithexpectationspriortomid-eclipse,atmid-eclipse,andatthirdcontact.

2. Theequivalentwidthdata for theD lines support thehypothesis thatsomeofthevariationinEWaretheresultofanon-homogeneousdisk,thatis,adiskthatispatchyorclumpy.

3. TheEWdatasupportthehypothesisthatthediskdoesnotabruptlyendatfourthcontact,butgraduallytrailsoff.

4. Theestimatedmid-eclipsedatebasedonthesodiumDlinesisAugust17, 2010. This estimate does not differ substantially from the projectedmid-eclipsedate(madepriortomid-eclipse)ofAugust4,2010.

5. TheNaD2andD1radialvelocitiesreachedtheirhighestvalue,ablueshift,of23.842km/secand23.843km/sec,respectively,onJanuary17,2011.

6. TheEWandradialvelocitydatasupportthehypothesesofaringstructuretothediskasothershaveproposed.Theauthorproposesasanalternativealargevoidwithinthedisk.

7. The5853Ålineradialvelocityprofilesupportsthehypothesisthatthe5853Åabsorptionlinehasadiskcomponent.

8. Theradialvelocitydatasupportstheexistenceofacentralclearingaround theunseenprimaryobjectof thedisk, that is, thediskhasaninnerboundary.

9. The 5853Å absorption profile contains a split line. The estimateddurationofthesplitlineeventwasestimatedtobe101days.

6. Acknowledgements

Iwould like to thankJeffHopkins forencouragingme to join theeAurCampaign, and for encouraging me to concentrate my spectroscopy on thesodiumDlinesregion.IwouldalsoliketothankJeffHopkinsforsuggestingthatIpurchasetheMeade16-inchLX200Rtelescopewaybackintheyear2005.


Ithasturnedouttobeasuperbtelescopefordoingspectroscopy.WithouthissuggestionImightstillbeattemptingtoretrofitmyold12.5-inchDall-Kirkham,madebyamachinistfriend,insteadofparticipatinginthiscampaign.

References

Gorodenski,S.2011,Soc. Astron. Sci. Newsl.,9(no.2),5.Hopkins, J. L. 2012, eAur Campaign website (http://www.hposoft.com/

EAur09/Starinfo.html).Hopkins, J.L.,andStencel,R.E.2008,Epsilon Aurigae: a Mysterious Star

System,HopkinsPhoenixObservatory,Phoenix,Arizona.Kim,H.2008,J. Astron. Space Sci.,25,1.Kloppenborg,B.2012,privatecommunication.Leadbeater,R.2011,“TheInternationalEpsilonAurigaeCampaign2009–2011.

A Description of the Campaign and early Results,” arXiv:1101.1435v1[astro-ph.SR),67.

Leadbeater,R.2012,eAurspectraldatabase(http://www.threehillsobservatory.co.uk/astro/epsaur_campaign/epsaur_campaign_spectra_table.htm),profile20080727-031309-epsAur-5x300s_P_1C_FULL.fit.—

Leadbeater, R., and Stencel, R. E. 2010, “Structure of the Disc of EpsilonAurigae:SpectroscopicObservationsofneutralPotassiumduringEclipseIngress,”arXiv:1003.3617v2[astro-ph.SR].

Leadbeater,R.,et al.,2011,Bull. Amer. Astron. Soc.,43,257.04.Seebode,S.,Howell,S.B.,Drumheller,D.,Stanford,D.,Hoard,D.W.,and

Stencel,R.E.2011,Bull. Amer. Astron. Soc.,43,257.08.


20

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2010

Feb

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224

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2010

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2010

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2010

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2010

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2010

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6

2010

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324

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3.69

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e1.

eA

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s)a

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and

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lian

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wer

EW

U

pper

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wer

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N

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Con

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f. (Å

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Lim

it (Å

)

Lim

it (Å

) Li

mit

(Å)

Li

mit(

Å)

Lim

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)

Lim

it (Å

)


20

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6479

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13

1.41

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1.44

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1.26

97

1.29

76

1.32

56

.049

6.0

655

.081

4

2010

May

08

324

5532

4.65

8241

1.

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1.

4215

1.

4642

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0

2010

Aug

05

224

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2010

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24

124

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2010

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08

124

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98

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4

2010

Nov

04

124

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6778

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4508

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57

1.63

83

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99

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05

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904

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2

2010

Nov

04

324

5550

4.75

3403

1.

6113

1.

6394

1.

6675

1.

4716

1.

4981

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00

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577

.073

2

2010

Dec

07

224

5553

7.79

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1.

7341

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7717

1.

8092

1.

6318

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48

1.77

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1.80

11

1.63

52

1.65

91

1.68

31

.037

9.0

525

.067

2

2010

Dec

25

124

5555

5.73

8889

1.

7719

1.

8017

1.

8316

1.

6643

1.

6941

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7239

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545

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780

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58

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1.86

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4

2011

Jan

17

124

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150

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8

2011

Jan

27

124

5558

8.68

5625

1.

7520

1.

7767

1.

8014

1.

6632

1.

6888

1.

7144

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428

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11Ja

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2

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41

1.80

06

1.83

71

1.66

78

1.69

81

1.72

85

.099

5.1

175

.135

4

Tabl

e1.

eA

ur,e

quiv

alen

twid

ths(

inÅ

ngst

rom

s)a

nd9

5%c

onfid

ence

lim

itsfo

rNa

D2,

Na

D1,

and

the

5853

Åli

ne,c

ont.

D

ate

Spec

trum

Ju

lian

Na

D2

Na

D2

Na

D2

Na

D1

Na

D1

Na

D1

5853

Å 58

53Å

5853

Å

Se

quen

ce

Dat

e Lo

wer

EW

U

pper

Lo

wer

EW

U

pper

Lo

wer

EW

U

pper

.

N

umbe

r

Con

f. (Å

) C

onf.

C

onf.

(Å

) C

onf.

Con

f. (Å

) C

onf.

Lim

it (Å

)

Lim

it (Å

) Li

mit

(Å)

Li

mit(

Å)

Lim

it (Å

)

Lim

it (Å

)

Tabl

e co

ntin

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2011

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2011

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2011

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2011

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2011

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2011

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Tabl

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s

Gorodenski, JAAVSO Volume 40, 2012758Ta

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358

53.0

654

—

2011

Apr

13

324

5566

4.65

8252

58

89.5

331

5895

.513

558

53.0

611

—

2011

Apr

26

124

5567

7.61

6528

—

—

58

53.1

024

5853

.074

2

2011

Apr

26

224

5567

7.63

1076

58

89.5

672

5895

.534

958

53.1

409

—

2011

Apr

26

324

5567

7.64

7581

58

89.5

658

5895

.537

158

53.1

361

—

2011

May

08

124

5568

9.62

7975

58

89.5

490

5895

.531

558

53.2

246

5853

.174

1

2011

May

31

124

5571

2.62

6944

58

89.6

136

5895

.605

258

53.4

914

5853

.133

0

2011

Aug

16

124

5578

9.86

2280

58

89.8

000

5895

.747

458

53.8

034

—

2011

Aug

16

224

5578

9.87

6863

58

89.8

108

5895

.747

958

53.7

481

—Ta

ble

cont

inue

d on

nex

t pag

e


20

10F

eb1

31

2455

240.

7193

52

8.85

610

.164

2.

233

—

2010

Feb

13

224

5524

0.74

0081

9.

304

10.7

74

2.86

8—

20

10F

eb1

33

2455

240.

7622

22

10.5

87

11.8

57

2.66

8—

20

10F

eb1

41

2455

241.

6865

28

8.29

69.

773

1.32

1—

20

10F

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42

2455

241.

7129

86

10.2

81

11.0

44

2.35

1—

20

10F

eb1

43

2455

241.

7344

44

9.40

611

.227

3.

713

—

2010

Feb

19

124

5524

6.63

3507

11

.915

12

.457

6.

192

—

2010

Feb

19

224

5524

6.65

1863

11

.452

11

.873

6.

202

—

2010

Feb

19

324

5524

6.66

9815

11

.513

12

.752

6.

427

—

Tabl

e4.

eA

ur,r

adia

lvel

ociti

es(k

m/s

ec)f

orN

aD

2,N

aD

1,th

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D

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Spec

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lian

Na

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Å 58

53Å

Sequ

ence

D

ate

(Å)

(Å)

(Å)

Split

Num

ber

Line

(Å)

Tabl

e co

ntin

ued

on fo

llow

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page

s

Tabl

e3.

eA

ur,l

ine

cent

ere

stim

ates

inÅ

ngst

rom

sfor

Na

D2,

Na

D1,

the

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split

line

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um

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Split

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(Å)

(Å)

20

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ug3

01

2455

803.

8519

56

5889

.814

158

95.7

765

5853

.771

4—

20

11A

ug3

02

2455

803.

8650

93

5889

.831

358

95.7

729

5853

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7—

20

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ep1

81

2455

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8131

37

5889

.819

658

95.7

627

5853

.459

958

53.3

919

20

11O

ct1

01

2455

844.

7709

72

5889

.786

558

95.7

378

5853

.635

4—

Gorodenski, JAAVSO Volume 40, 2012760Ta

ble

4.e

Aur

,rad

ialv

eloc

ities

(km

/sec

)for

Na

D2,

Na

D1,

the

5853

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ne,a

ndth

e58

53Å

split

line

(neg

ativ

eva

lue

=bl

ueD

oppl

er

shift

;pos

itive

val

ue=

red

Dop

pler

shift

),co

nt.

D

ate

Spec

trum

Ju

lian

Na

D2

Na

D1

5853

Å 58

53Å

Sequ

ence

D

ate

(Å)

(Å)

(Å)

Split

Num

ber

Line

(Å)

20

10F

eb1

94

2455

246.

6800

93

11.5

49

12.6

76

7.10

3—

20

10F

eb2

61

2455

253.

6541

90

12.0

58

13.5

61

8.91

1—

20

10M

ar0

41

2455

259.

6502

89

14.0

48

15.0

50

14.7

09

—

2010

Mar

04

224

5525

9.66

9225

12

.460

13

.612

13

.234

—

20

10M

ar0

43

2455

259.

6896

99

13.8

80

14.4

35

12.0

20

—

2010

Mar

13

124

5526

8.68

1319

15

.529

16

.250

12

.885

—

20

10M

ar1

32

2455

268.

7024

88

14.4

55

15.2

03

9.96

1—

20

10M

ar1

33

2455

268.

7223

38

14.7

50

15.3

40

16.0

40

—

2010

Mar

28

124

5528

3.65

3206

16

.526

17

.501

2.

965

6.13

5

2010

Mar

28

224

5528

3.67

4873

16

.878

16

.937

4.

881

8.92

7

2010

Mar

28

324

5528

3.69

5197

15

.697

16

.693

4.

358

—

2010

May

08

124

5532

4.63

6933

15

.183

15

.045

6.

248

—

2010

May

08

224

5532

4.64

7917

15

.198

15

.559

12

.378

—

20

10M

ay0

83

2455

324.

6582

41

14.4

24

14.5

27

10.3

55

—

2010

Aug

05

124

5541

3.91

9329

1.

283

–0.1

83

–9.1

83

—

2010

Aug

05

224

5541

3.93

7581

1.

272

–0.0

41

–9.0

34

—

2010

Aug

05

324

5541

3.95

7431

–0

.285

0.

112

–9.0

04

—

2010

Sep

24

124

5546

3.80

8264

–

11.7

07

–11.

105

2.53

01.

398

20

10S

ep2

42

2455

463.

8252

20

–11

.534

–1

0.99

81.

444

—

2010

Oct

08

124

5547

7.79

0775

–1

4.33

3–1

3.91

7–6

.755

—

Tabl

e co

ntin

ued

on fo

llow

ing

page

s


Tabl

e4.

eA

ur,r

adia

lvel

ociti

es(k

m/s

ec)f

orN

aD

2,N

aD

1,th

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line

,and

the

5853

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litli

ne(n

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valu

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blue

Dop

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ift;p

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vev

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dD

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ift),

cont

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ate

Spec

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Ju

lian

Na

D2

Na

D1

5853

Å 58

53Å

Sequ

ence

D

ate

(Å)

(Å)

(Å)

Split

Num

ber

Line

(Å)

20

10O

ct0

82

2455

477.

8118

17

–15.

224

–15.

005

–7.1

04

—

2010

Nov

04

124

5550

4.72

8750

–2

0.18

7–1

9.53

6–6

.171

—

20

10N

ov0

42

2455

504.

7410

42

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.760

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9.72

4–5

.690

—

20

10N

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43

2455

504.

7534

03

–19

.643

–1

9.28

2–5

.547

—

20

10D

ec0

71

2455

537.

7798

96

–22

.356

–2

1.41

3–2

.325

—

20

10D

ec0

72

2455

537.

7922

92

–21

.302

–2

0.59

9–2

.253

–0

.359

20

10D

ec0

73

2455

537.

8036

46

–22

.096

–2

1.73

3–3

.600

—

20

10D

ec2

51

2455

555.

7388

89

–22

.035

–2

2.14

0–1

7.54

7—

20

10D

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52

2455

555.

7500

00

–22

.004

–2

1.75

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6.78

4—

20

11Ja

n17

1

2455

578.

7184

61

–23.

842

–23.

843

–12.

763

–6.0

49

2011

Jan

17

224

5557

8.73

7396

–

23.0

38

–23.

019

–12.

164

—

2011

Jan

27

124

5558

8.68

5625

–2

1.92

8–2

2.08

9–5

.106

–1

2.83

5

2011

Jan

27

224

5558

8.69

7546

–2

3.59

3–2

3.29

9–9

.147

–1

1.26

2

2011

Feb

12

124

5560

4.66

3553

–2

2.16

7–2

2.13

5–1

3.02

4–1

6.77

8

2011

Feb

12

224

5560

4.67

9606

–

21.6

07

–21.

667

–9.0

09

–16.

681

20

11M

ar0

51

2455

625.

6390

16

–21

.933

–2

0.98

5–1

4.68

4—

20

11M

ar0

52

2455

625.

6499

19

–21.

287

–20.

533

–15.

800

–20.

348

20

11M

ar0

53

2455

625.

6605

67

–20.

040

–19.

785

–15.

278

–19.

764

20

11M

ar0

54

2455

625.

6731

25

–21

.699

–2

1.50

9–1

3.90

5–2

1.90

0

2011

Mar

10

124

5563

0.68

7222

–2

0.58

9–2

0.98

5–1

6.49

7–1

9.96

9Ta

ble

cont

inue

d on

nex

t pag

e


20

11M

ar1

02

2455

630.

6972

22

–20.

854

–20.

360

–13.

173

–19.

913

20

11M

ar1

03

2455

630.

7084

61

–20

.778

–2

0.64

5–1

5.76

4–1

9.32

4

2011

Mar

23

124

5564

3.66

7616

–2

0.90

0–2

0.87

9—

—

20

11M

ar2

32

2455

643.

6519

56

–22

.432

–2

1.48

9–2

2.95

5—

20

11M

ar2

33

2455

643.

6821

64

–21.

658

–20.

823

–20.

512

–14.

996

20

11A

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21

2455

653.

6389

58

–19.

719

–19.

663

–27.

744

—

2011

Apr

02

224

5565

3.64

8762

–2

0.91

0–2

0.28

9–2

7.91

8—

20

11A

pr1

31

2455

664.

6380

56

–20

.783

–2

0.57

9–2

8.86

6—

20

11A

pr1

32

2455

664.

6478

01

–20.

605

–20.

375

–28.

405

—

2011

Apr

13

324

5566

4.65

8252

–2

1.22

0–2

0.67

0–2

8.62

5—

20

11A

pr2

61

2455

677.

6165

28

–24

.127

–2

3.46

2—

–2

7.95

4

2011

Apr

26

224

5567

7.63

1076

–1

9.48

5–1

9.58

2–2

4.53

8—

20

11A

pr2

63

2455

677.

6475

81

–19

.556

–1

9.47

0–2

4.78

4—

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81

2455

689.

6279

75

–20.

411

–19.

755

–20.

251

–22.

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20

11M

ay3

11

2455

712.

6269

44

–17

.123

–1

6.00

7–6

.586

–2

4.94

3

2011

Aug

16

124

5578

9.86

2280

–7

.635

–8

.776

9.

393

—

2011

Aug

16

224

5578

9.87

6863

–7

.085

–8

.751

6.

561

—

2011

Aug

30

124

5580

3.85

1956

–6

.917

–7

.297

7.

754

—

2011

Aug

30

224

5580

3.86

5093

–6

.042

–7

.480

6.

130

—

2011

Sep

18

124

5582

2.81

3137

–6

.637

–7

.998

–8

.200

–1

1.68

2

2011

Oct

10

124

5584

4.77

0972

–8

.322

–9

.265

0.

789

—

Tabl

e4.

eA

ur,r

adia

lvel

ociti

es(k

m/s

ec)f

orN

aD

2,N

aD

1,th

e58

53Å

line

,and

the

5853

Åsp

litli

ne(n

egat

ive

valu

e=

blue

Dop

pler

sh

ift;p

ositi

vev

alue

=re

dD

oppl

ersh

ift),

cont

.

D

ate

Spec

trum

Ju

lian

Na

D2

Na

D1

5853

Å 58

53Å

Sequ

ence

D

ate

(Å)

(Å)

(Å)

Split

Num

ber

Line

(Å)


Figure1.ThesodiumDlinesregionencompassingthe5853Åline.ThisisanormalizedspectrumtakenonFebruary26,2010.

February 14, 2010 November 4, 2010 December 7, 2010

January 17, 2011 May 8, 2011 October 10, 2011

Figure2.ExamplespectratoillustrateevolutionofthesodiumDlines.

Figure3.ThesodiumD2lineequivalentwidths(inÅngstroms)withupperandlower95%confidencelimits.


Figure4.ThesodiumD1lineequivalentwidths(inÅngstroms)withupperandlower95%confidencelimits.

Figure 5.The 5853Å line equivalent widths (in Ångstroms) with upper andlower 95% confidence limits, and a superimposed second order polynomialregressionline.

Figure6.ThesodiumD2radialvelocities(km/sec)andasuperimposedsecondorderpolynomialregressionline.


Figure7.ThesodiumD1radialvelocities(km/sec)andasuperimposedsecondorderpolynomialregressionline.

Figure 8. The 5853Å radial velocities (km/sec) and a superimposed secondorderpolynomialregressionline.

Figure9.The5853Ålineradialvelocities(km/sec)andasuperimposedfirstorderpolynomialregressionline.


Figure10.Evolutionprofilesofthe5853Åsplitline.

March 28, 2010 September 24, 2010 December 7, 2010

December 25, 2010 January 17, 2011 January 27, 2011

February 12, 2011 March 5, 2011 March 10, 2011

March 23, 2011 April 26, 2011 May 8, 2011

May 31, 2011 September 18, 2011

Geiseetal., JAAVSO Volume 40, 2012 767

Eclipse Spectropolarimetry of the ε Aurigae System

Kathleen M. GeiseRobert E. StencelUniversity of Denver, Department of Physics and Astronomy, 2112 E. Wesley Avenue, Denver, CO 80208; address email correspondence to [email protected]

Nadine MansetCanada-France-Hawaii Telescope Corporation (CFHT), Waimea Headquarters, 65-1238 Mamalahoa Highway, Kamuela, HI 96743

David HarringtonJeffrey KuhnInstitute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822

Received April 13, 2012; revised August 27, 2012, October 17, 2012; accepted November 4, 2012

Abstract Therecenteclipseoftheenigmaticbinarystarsystem,eAurigae,offered a special opportunity to explore the role of spectropolarimetryin discovery of unknown facets of the objects involved. Here we presentspectropolarimetricresultsforH-alpha,H-beta,CaI(422.6nm),andKI(769.9nm)basedonmorethan50epochsofhighdispersionspectraobtainedwiththeESPaDOnSinstrumentatCFHTduring2006–2012.

1. Introduction

The target, eAur, is a single line spectroscopic binary that features anopaquedisk,surroundingahiddencompanion,thatcausesalengthyeclipseevery 27 years—for a reading list, see, for example, Stencel et al. (2011).Instrumentationadvancesofthepastdecadehaveenabledaremarkablesetofnewspectropolarimetricdatatobeobtainedduringthe2008–2011eclipse.TheESPaDOnSinstrument(Donati2003)attheCanada-France-HawaiiTelescopeobtainedmorethan50epochsoffullStokespolarimetryfrom3800Åto10000Å.Prior efforts have revealed broadband polarization changes during eclipses,successfully predicting some disk characteristics, as well as demonstratingpost-eclipse variability (Kemp et al. 1986; Cole 2012). SpectropolarimetricobservationsmaycontributetoourunderstandingofthesystembyrevealingthenatureanddistributionofgaseousmaterialintheF-staratmosphereandintheoccultingdisk.Thispaperprovidesadescriptionofdataanalyzedtodate.Our preliminary results indicate that the increased polarization observed inbroadbandduringeclipseisalsopresentinmanyspectrographiclines.

Geiseetal., JAAVSO Volume 40, 2012768

2. Observations

Thedatawereobtainedusing theEPSaDOnS instrument at theCanada-France-Hawaii telescope (CFHT). ESPaDOnS is a cross-dispersed échellespectropolarimeterdesignedtoobtainacompleteopticalspectruminasingleexposure,witharesolvingpowerofabout70,000.TheeAurdatausedinthisreportwereobtainedwithabout106countsperspectralbin.Thenormalizedintensity (normalized to 1) corresponds to an average uncertainty of about1×10–3,forasignal-to-noise(S/N)ofc.1000.AllfourStokesparametersweretakenforeachobservation(seeTable1foralogofobservations). WeretrievedESPaDOnSobservationsofeAurfromtheCanadianAstronomyData Centre (CADC), CFHT Science DataArchive (http://www1.cadc-ccda.hia-iha.nrc-cnrc.gc.ca/cadc/).FiftyepochsofspectropolarimetricobservationsofeAur span the time from pre-eclipse (beginning February 2006) throughtheeclipsephasesandincludepost-eclipseobservations(forexample,January2012).The data were automatically reduced with Upena, CFHT’s reductionpipelineforESPaDOnS.Upenauseslibre_esprit,whichisaproprietarydatareductionsoftwaretool(Donatiet al.1997).

2.1.ContributionsofpolarimetrytothestudyofeAur Polarizationsignaturesoccurwhensymmetriesarebroken.Possiblesourcesofpolarizationare rotationdeformities, asphericalwinds, tidaldistortions inbinary systems, the Chandrasekhar effect during eclipse of binary systems,photosphericinhomogeneitiesincludingradiationinhomogeneities,andmatterstreamsoraccretion.Polarizationsignaturesduetoscatteringdependuponthenatureanddistributionofthescatterers:electrons,atomicspecies,and/ordustgrains.Broadbandpolarizationsignatures(forexample,seeCole2012;Hensonet al.2012;Kempet al.1986;Coyne1972)mayincludecontributionsfromboththecontinuumandlinesthatmayinvolvedifferentscatteringagents. The spectropolarimetric observations included in this paper revealanisotropies in gaseous atomic species intrinsic to the F star, as well asgeometric and/or scattering effects of the disk during eclipse. One possiblegeometricsourceofpolarizationinlinesduringeclipseistheChandrasekhareffectassociatedwithlimbpolarizationof theFstar.Onepossiblesourceofpolarizationout-of-eclipse isanisotropyassociatedwithstellarpulsation, forexample.Ourgoal is to identify the sourceor sourcesofpolarization in thelinesbothin-anout-of-eclipserevealedbytheseexcellentESPaDOnShigh-resolutionobservations.ESPaDOnSobservationscannotbeused tomeasurecontinuumpolarization(http://www.cfht.hawaii.edu/Instruments/Spectroscopy/Espadons/).


3. Method

Linearpolarization,P,wascomputedusingnormalizedQandU(thatis,Q/IcandU/Ic)foreachwavelengthintheobservationaccordingtoEquation(1)(Bagnuloet al.2009).

Percentlinearpolarizationwascalculatedasfollows

+Q

Ic

2

U

Ic

2

P

Ic

=√

(1)

WhereI/Icdenotes thenormalizedintensity.Percentq (%q),percentu (%u).andpercentv (%v),whereq,u,andvarethenormalizedStokesparameters,werecalculatedinamannersimilartoEquation(2). Assessing the true errors in polarimetric measurements is crucial toestablishingthephysicsofthesource.WeassumethattheStokesparametersQandUarenormallydistributedabouttheirtruevalues,butithasbeenshownthat linear polarization follows a Rice distribution (for example, Clarke andStewart1986).TheRiceprobabilitydistributionisgivenby

(2)%p= ×100P /Ic

I /Ic

Here p0 is the underlying, true, polarization, I0 is the zeroth-order modifiedBessel function, and the underlying Gaussian noise has variance σ2. In thelimitofhighsignal-to-noise(S/N),theRicedistributionapproachesthenormaldistribution, with a mean that approaches p0 and a standard deviation thatapproaches σ (Vaillancourt 2006). The Rice mean is given by

R( p|p0,s)=ps2

exp –p2+p02

2s2 I0

pp0s2

⎤⎦

⎡⎣

⎛⎝

⎛⎝ (3)

HereL½(x) is a Laguerre polynomial of order ½, μ is the mean, and σ is the standarddeviation.TheRicevarianceisgivenby

(4)mR = √⎛⎛p

2 sL½–m2

2s2⎛⎛

Here L2½(x) is a generalized Laguerre polynomial Ln

(α)(x) with n = ½ andα = 2. The Rice standard deviation may be found by taking the square root ofthevariance.

(5)12

ps2 L2½⎛⎛–m2

2s2⎛⎛

⎛

⎛⎥

⎠

⎛⎥ ⎛

⎛⎥

⎠

⎛⎥


Bydefinition,theparameterpisapositivedefinitequantity.TheindividualpolarizationvaluescalculatedfromEquation(1)willalwaysbepositiveandnon-zerobecausetheindividualvaluesofQandUwillgenerallybenon-zero.AtlargeS/N( p /σ ≥ 4) the maximum likelihood and most probable estimators forthelinearpolarization(forexample,SimmonsandStewart1985)convergeto

Equation(6)correctsforthepositivebiasinthelinearpolarizationcalculatedusingEquation(1)(Clarke2010).Thedatapresentedherearenotcorrectedforinterstellarpolarization. Themeanvalueofpmaybecomputedusingthemeanvaluesofqandu(ClarkeandStewart,1986)asfollows

(6)p= (p2–s2)√

Thebarredvariablesdenotethemean. Linear polarization position angle, Θ, may be computed from Stokes qanduasfollows(Bagnuloet al.2009).Positionangleswillrangefrom0to180degrees.

(7)–p= ( –q 2+–u 2)√

TheESPaDOnSdataarenoisieratshorterwavelengths(thatis,towardtheblue)thanlongerwavelengthsbecausethedetectorislesssensitiveintheblue.Webinnedthelinearpolarizationdatawithawavelengthbinof0.015nmusingtheerror-weightedmean(forexample,Taylor1997)toboostsignal-to-noiseatshorterwavelengthsandfordeepabsorptionlines.Wedeterminedthroughtrialanderror that thiswas the largestbinsize thatdidnotseriouslydegrade theresolutionoftheline.Insomecases,wecombinedseveralepochs(usingtheerror-weightedmean)tofurtherreducenoisepriortowavelengthbinning,usingthecriterionthatthelineprofiledidnotchangebetweenbinnedepochs. Wecomputed themeanforbothqanduusing thebinneddataand thencomputedthemeanlinearpolarizationusingEquation(7).TheRicemeanand

(8)12

⎛⎛ ⎛⎛Q= tan–1 uq +Q0

Q0=

0ifq>0andu ≥ 0180ifq>0andu<0

90ifq<0⎨⎧

⎩⎨⎧

⎩

Q=45ifq=0andu>0135ifq=0andu<0⎨

⎧

⎩⎨⎧

⎩

(9)


variancewerecomputedforeachpusingEquations(4)and(5),adoptingthemean polarization for μ in those equations. Finally, we bias-corrected the linear polarization using Equation (6), adopting the Rice standard deviation for σ in thatequation.Weadoptedtheerrorbarsgiveninthepipelinereductionastheuncertainty in both normalized intensity and normalized Stokes parametersandpropagatedthoseuncertaintiesincalculationsofpercentStokes(see,forexample, error bars in Figure 2). We also propagated the uncertainty (Ricestandarddeviation) in the calculationof%p (see, for example, errorbars inFigure1). For polarizations with large S/N, the confidence regions approach thosegivenbyanormalGaussiandistributioncenteredonthebias-correctedvalueofp, with 2σ corresponding to 95% and 2.6σ corresponding to 99% confidence for p/σ ≥ 4 (Vaillancourt 2006). The maximum likelihood estimator (Equation 6) of theunderlying(“true”)polarizationconvergeswithallotherestimatorswhenp/σ is greater than 4. For p/σ greater than 3 and less than 4, the maximum likelihood estimator may not completely correct for bias; the polarization isconsidered the upper bound.Values of p/σ less than 1.4 correspond to zero polarization (Vaillancourt 2006). We identified spectroscopic regions withsignificantlinearpolarizationbyflaggingpolarizationpeaksforp/σ ≥ 4. We rotated theunbinneddataby27degreesusinga rotationmatrix (forexample,Code andWhitney1995;Bagnuloet al. 2009) to align instrumentnorthwiththerotationaxisofthesystemasdescribedbyKloppenborget al.(2010) before binning by epoch and wavelength. We confirmed that theinvariant,(Q2+U2),wasconservedunderrotation(intensityisunaffectedbyrotationand%pisunaffectedaslongastheinvariantisconserved). WeverifiedthatthenullparametersprovidedbytheESPaDOnSpipelinecontainednosignal,indicatingthatanyinstrumenteffectswereremovedbythedatareduction.WewerealsocarefultochangethesignofStokesUasdirectedbytheESPaDOnSFITSfileheaders.

4. Analysis

4.1.Linearpolarizationtimeseriesandqu-plots Initial analysis focused on the stronger lines in order to assess whethertheeclipseresultedinchangestothepolarization.Asampletime-seriesofH-alphalineprofilesandpolarizationsareshowninFigure1.Asampleplotof%qvs.%u(aqu-plot)isshowninFigure2.Theerrorbarsinthequ-plotarethe1s-propagated(assumedGaussian)averageuncertainties inboth%qand%u.Theanglefromthe+qaxismeasuredcounterclockwisetoafeatureinthequ-plot corresponds to twice the position angle (2Θ) as measured east of north andmaybeausefuldiagnosticofthegeometryofthescatteringgivingrisetothepolarization.Wewerecareful to exclude%qand%ucontributions fromneighboringlinesintheseplotswhenpossible.


4.2.Hydrogenalpha Wefit thepre-eclipseH-alpha line (restwavelength656.280nm)withaGaussianfunctionandadoptedtheHWHMoftheGaussian(c.25kms–1)asthelinecore.Wefurtherdefinedthewingsasfollows:thebluewing(–125kms–1to–25kms–1)andtheredwing(25kms–1to125kms–1).Regionsoutsideofthesedefinedareasconsistentlymappedto(0,0)inthequ-plots.Thesedefinitionsaremaintainedthroughoutthefollowinganalysis. H-alpha exhibited persistent polarization in the line core in all epochs(seeFigure1).Duringpre-eclipse,thelinecoreaccountedforanearlylinearexcursionof(–%u,–%q)inthequ-plot(greendiamondsymbol,Figure2).Thelinewas largely symmetric,withboth red andblue emissionwings evident.ThelineappearedslightlybroadenedtotheredwhencomparedtotheGaussianfunction.Theblueandredemissionwingsexhibitednopolarizationfeaturesinthisbinnedepoch,orinanypre-eclipseepoch.AtnophasedidtheH-alphalinereachzerointensity. HarringtonandKuhn(2009)notedthestrongpresenceofspectropolarimetricsignaturesinandaroundtheabsorptivecomponentsof theH-alphaemissionlineinHerbigAe/Bestarsthattheycalled“polarization-in-absorption.”Theyalsoidentifiedabroadpolarizationsignatureacrossemissionfeaturesformanyclassical Be stars in their sample. HerbigAe/Be stars are embedded in coldgasanddust,whichmaybeequatoriallyenhanced,whereasclassicalBestarsarerapidrotatorscharacterizedbyionizedequatorialmaterial.Theequatorialmaterialsurroundingthesetwotypesofstarscontributestodistinctlydifferentpolarization signatures.Thepolarization featuresweobserved in pre-eclipseeAur spectra are similar to “polarization-in-absorption”; this suggests thateAurdoesnothaveanequatorialenhancementofionizedmaterial. At mid-eclipse, and for many epochs following mid-eclipse, the lineexhibitedacentralemissionfeature(presumedrecombination,seeStencelet al.2011).%pincreased,consistentwithchangestobroadbandpolarizationreportedbyCole (2012) andKempet al. (1986).Thecorepolarizationpeakappearsnotchedin theseepochs,possibly indicatingadepolarizationassociatedwiththeemissioncore.Atmid-eclipse,theblueandredabsorptionwingsexhibitedbroad %p polarization.There were excursions in the qu-plot for features inthelinecore(–%q;greendiamondsymbol),aswellastheblue(+%q,+%u;bluesquaresymbol)andred(+%q,–%u;redtrianglesymbol)absorptionwings(Figure 2). These qu-plot excursions were not affected by binning and areevidentinseveralobservationsaroundthistime. By lateeclipse, the lineexhibitedabroad,deep,blue-shiftedabsorption.Normalizedintensitydroppedtoabout10%atthedeepestpartoftheline,butsignal-to-noise remained above 700 and the ratio p/σ ranged from 3 to 25 for polarizationgreaterthan0.4%,significantwithintheRicestatistics.Thecentralcore polarization remained strong (>1%) in late eclipse, but the blue wingpolarizationincreased(>0.5%at–100kms–1),whiletheredwingpolarization


decreased (that is, negligible at 100 km s–1). In the qu-plot, the line coreaccountedforthe–%qfeatures(greendiamonds),thebluewingaccountedforthe+%qfeatures(bluesquares),andtheredwingpolarization(redtriangles)was largely concentratedat (0,0) (Figure2).Thus, thepolarizationbehaviorfollowedthelinebehaviorinthisepoch. TheH-alphalinedidnotreturntoitspre-eclipseformbythetimeofourlastpost-eclipseobservation(January17,2012).Theredemissionwingreappearedat about the pre-eclipse level, but the blue emission wing was masked by abroad(>–150kms–1),shallow(normalizedintensityc.0.9)absorption.Linecorepolarization remainedabove1%and thebluewingpolarization featuredisappeared. The line core polarization maintained a largely (–%q, +%u;greendiamonds)orientationinthequ-plot(seethepost-eclipsebinnedepochpresentedinFigure2). Clearly,thepassageoftherotating,darkdiskinfrontoftheFstarinducespolarizationsignalsawayfromlinecenter.ContinuingobservationsmaybeabletodemonstratewhetherthepersistentlinecorepolarizationtrackstheFstaroradisk-tiedsourcevelocityaroundtheorbit.

4.3.Hydrogenalphalinearpolarizationpositionangle Wecalculated thepositionanglefor(%q,%u)pairsfor theH-alpha lineinmid-eclipse(Figure3).Thedataarerotatedtothestellarframeandarenotbinned. Notice that the linear polarization position angle appears randomlyscattered outside of the line, which is expected. The position angles thatcorrespond to the line core (± 25 km s–1 from rest wavelength) are plottedin green; position angles corresponding to the blue-shifted absorption wing(–125kms–1to-25kms–1)areplottedinblue;andpositionanglescorrespondingtothered-shiftedabsorptionwing(+25kms-1to+125kms-1)areplottedinred.Positionanglesonlyrangefrom0° to180°becauseof thenatureof theStokesparameters;apositionangleof180°isconsistentwith0°.Noticethelinecorepolarizationisoffsetbyabout90°fromthewings.Thismaybeanopacityeffect.Comparethesedatatothemid-eclipsequ-plot(Figure2).

4.4.Hydrogenbeta Unlike the pre-eclipse H-alpha line, the H-beta line (rest wavelength486.135nm) was better fitted by a Lorentzian profile and we adopted theHWHMofthisprofile(c.35kms–1)asthelinecore.Wefurtherdefinedthewingsasfollows:thebluewing(–125kms–1to-35kms–1)andtheredwing(35kms–1to125kms–1)andnotedthatregionsoutsideofthedefinedareasconsistentlymappedto(0,0)inthequ-plots.Thesedefinitionsaremaintainedthroughoutthefollowinganalysis. H-betaalsoexhibitedpersistentpolarizationinthelinecoreinallepochs(see Figure 4). In pre-eclipse, the normalized intensity was at 13%, but thesignal-to-noise remained above 1,000. The ratio p/σ was consistently greater


than4for%pgreaterthan0.22%.The–%qexcursioninthequ-plot(Figure5)corresponds to linecorepolarizationanddiffers inorientation fromH-alphapre-eclipse(seeFigure2).Thelineitselfappearednearlysymmetricandred-shiftedbyaboutthevelocityoftheFstaratthatphase. The H-beta line maintained a deep and broad absorption at mid-eclipsethatdeepened furtherby lateeclipse.%p increased inmid-and lateeclipse.Atmid-eclipse,thenormalizedintensityfelltoabout5%atthedeepestpartoftheline,butsignal-to-noiseremainedgreaterthan500.Thelinearpolarizationwasgreatestatthelinecore,withsmallercontributionsfromtheblueandredabsorption wings. The ratio p/σ remained consistently greater than 4 for %p ≥ 0.2% in this epoch. There were excursions in the qu-plot for features in the linecore(–%q;greendiamond),aswellastheblue(+%q,+%u;bluesquare)andred(+%q,–%u;redtriangle)absorptionwings(Figure5).Thesequ-plotexcursionsaresimilartothoseexhibitedbyH-alphaforthisepoch. By lateeclipse, the lineexhibitedabroad,deep,blue-shiftedabsorption.Thelineisclearlysaturatedinlateeclipse,fallingtojust1.6%intensityatthedeepest point and, although S/N is nearly 200 here, the ratio p/σ is only 1.2; therefore %p = 0. The ratio p/σ ranged from 3 to 11 for %p > 0.4 outside the saturatedregion.Thecentralcorepolarizationappearstohavedecreased;thebluewingpolarization(outsideofthesaturatedregion)increased(>2%at–70kms–1),whiletheredwingpolarizationdecreased(c.0.2%at70kms–1)frommid-eclipselevels.Inthequ-plot,thelinecoreaccountedforthe–%qfeatures(p/σ ≥ 3 at –20 km s–1; p/σ ≥ 4 at –10 km s–1andthroughouttheremainderofthecore),theunsaturatedbluewingaccountedforthe+%qfeatures(Figure5;bluesquares)andtheredwingpolarizationwaslargelyconcentratedat(0,0).The polarization behavior also followed the line behavior in this epoch andqualitativelyresemblestheH-alphapolarization. The H-beta line did not return to its pre-eclipse form by the time ofour last post-eclipse observation (January 17, 2012). The line was deeper,broader,andblue-shiftedbyabout–20kms–1withastrong(c.1.5%),narrowpolarizationpeakcenteredonthisvelocity.Thelinewasdeep,butunsaturated,withnormalizedintensitynearly8%andsignal-to-noiseabove500.Theratiop/σ remained above 4 for %p greater than 0.5%. The line core polarization maintainedalargely–%qorientationinthequ-plot(seethepost-eclipsebinnedepochpresentedinFig.5).

4.5.HydrogengammaandHydrogendelta In pre-eclipse, H-gamma (rest wavelength 434.047 nm) appeared toexhibitlow-levelpolarizationfeatures,buttherewereinsufficientdatapointscorresponding to p/σ ≥ 4. H-delta (rest wavelength 410.008 nm) in pre-eclipse showed no polarization features. By mid-eclipse, both lines becamesaturated, making analysis of line core polarization impossible. However,both lines exhibited absorption wing polarization meeting the p/σ ≥ 4 criteria.


These features exhibited excursions in the qu-plot of +%u for blue-shiftedabsorptionand–%uforred-shiftedabsorptionforbothlines,whichisconsistentwith both H-alpha and H-beta polarization during this epoch. The linesremainedsaturated in lateeclipseand therewerenosignificantpolarizationfeaturespost-eclipseforeitherline.

4.6.Potassium(769.896nm) TheKIline(restwavelength769.896nm)describedhereistheweakerlineofadoubletthatarisesfromthegroundstate.Theout-of-eclipselineisthoughttohaveaninterstellarorigin(WeltyandHobbs,2001).TheKI769.896nmlineexhibitednopolarizationsignaturesuntilaftermid-eclipse.WeidentifiednoF-starcontribution;varyingabsorptionandpolarizationfeaturesdescribedbelowmaybeattributedtothedisk. Inpre-eclipse,thelineprofileremainedconstant;thestellarradialvelocitywas red-shifted with respect to the line rest wavelength (see Figure 6); andnolinearpolarizationfeatureswereobserved(seeexamples,Figures6and7).AGaussianfittothelineprofilereturnedaHWHMof0.02nm. Afterfirstcontact,thelineexhibitedared-shifted(about20kms–1)featureinitiallyaboutthesamedepthasthelinecore(normalizedintensityabout0.7)thatdeepenedtoanormalizedintensityofabout0.3.Therewerenosignificant(p/σ ≥ 3) polarization features evident until after second contact. The weak (c.0.3%),narrowlinearpolarizationfeaturethatappearedaftersecondcontactwascenteredonthered-shiftedcomponentoftheline. Bymid-eclipsethelineappeareddeeperandbroaderthanduringpre-eclipseepochs.Abroad,weak(<0.2%)linearpolarizationfeatureappearedwhichwascentered on the line (see Figure 6). In Figure 6, the ratio p/σ is greater than 3 for polarizationabove0.1%andisgreaterthan4forpolarizationabove0.15%;thepolarizationissignificantbyRicestatistics.Thestellarradialvelocitywasnotshiftedwithrespecttothelinerestwavelengthatmid-eclipse. The line developed a broad, blue-shifted component after mid-eclipse.Polarizationremainedlow(below0.2%)untillateeclipse,whenthelinewasverybroad.WefitaGaussianfunctiontothelateeclipselineprofile;thefityieldedaHWHMof0.05nm,morethantwicetheHWHMmeasuredinpre-eclipse. The Gaussian centroid corresponded to a shift of –20 km s–1 fromtherestwavelength.Alarger(c.0.5%)polarizationfeaturewascenteredonthe blue-shifted component of the line in this epoch (see Figure 6), whichcorresponded toa (–%q,+%u;bluesquares) loop in thequ-plot (Figure7).The star’s radial velocity became blue-shifted with respect to the line restwavelengthaftermid-eclipse. Thelineretainedablue-shiftedcomponentafter4thcontactthatdecreasedinbreadth anddepthover time.Therewerenopolarization features evidentafter4thcontact.Thelinehadnearlyreturnedtoitspre-eclipseformbyourlastobservation(January17,2012).


We examined the stronger line of the K I doublet, (rest wavelength766.490nm) and discovered that it exhibited line profile and polarizationvariations similar to the weaker line.At late eclipse, the line exhibited abroad,blue-shiftedabsorptioncomponent.Alinearpolarizationfeaturewascentered on the blue-shifted component and the qu-plot also exhibited a(–%q,+%u)loop.

4.7.Calcium(422.673nm) TheCaIline(restwavelength422.673nm)describedherearisesfromthegroundstateandshowsapersistentcorepolarizationsignatureinpre-,mid-andlateeclipsephases(Figure8).Thelateeclipsepolarizationappeareddramaticallygreater than the pre-eclipse phase.After first contact, the Ca I line exhibitsvariationssimilartotheKIline,withanadditionalabsorptioncomponentatabout+20kms–1fromthelinerestwavelengthbeforemid-eclipseandablue-shiftedadditionalabsorptioncomponentdevelopingatabout–20kms–1aftermid-eclipse. Wefitthepre-eclipseCaIlinewithaGaussianfunctionandadoptedtheHWHMoftheGaussian(36kms–1)asthelinecore.TheGaussiancentroidwasdisplacedfromrestby0.08nm(24kms–1),butthecalculatedradialvelocityofthestarwasonly8kms–1forthisepoch.WeconfirmedtheGaussianHWHMusing data for two later epochs (20081216, 20080213) when the Gaussiancentroidandstellarradialvelocityweremorecloselyaligned.Wedefinedthewingsasfollows:thebluewing(–125kms–1to–36kms–1)andtheredwing(36kms–1to125kms–1).Regionsoutsideofthesedefinedareasconsistentlymappedto(0,0) in thequ-plots.Thesedefinitionsaremaintainedthroughoutthefollowinganalysis. Thelineappearedasymmetricinthepre-eclipseepoch(Figure8)witharedabsorptioncomponentextendingbeyondthelinecore,atabout50kms–1.Alarge(c.1%)polarizationpeakwasnearlycenteredonthestarandasmaller(0.4%)linearpolarizationpeakwasassociatedwiththered-shiftedcomponent. The presence of two peaks in %p for this pre-eclipse epoch may beattributedtooneofthefollowing:(1)thelineisopticallythickatthelinecore(aswithH-alpha),(2)morethanoneasymmetricregioncontributestotheCaI422.6nmpolarization,or(3)thelinecontainsablendofspecieswithvaryingdegreesofpolarization.Twospecies,FeI(422.743nm,3.3eV,doublet)andTiII(422.733nm,1.13eV,multiplet33),arecandidatesforpossibleblendedspecies corresponding to the velocity offset of c. 50 km s–1. The possibleblended feature persisted at about the same polarization strength throughoutthetimeseries.ThecorrespondingFeIdoublet(422.545nm)toourcandidatelineexhibitednopolarizationinanyepoch.ThetwoothermembersoftheTiIImultiplet(421.818nmand420.592nm)didnotshowpolarizationfeatures.Hack(1959)identifiedaTiIIlineofcomparableenergytoourcandidateTiIIline(TiII,454.5nm,1.13eV,multiplet30)asasolelyFstarline.Thefeature


atc.50kms–1maybeaTiIIcomponentattributabletotheFstar. The qu-plot (Figure 9) describes two dominant position angles for thelinein thispre-eclipseepoch; theexcursionof(–%q,+%u;greendiamonds)correspondstothelinecoreandtheexcursion(+%q;redtriangles)correspondstotheredwing.Thepositionanglescorrespondingtotheexcursionsinthequ-plotdifferbyabout90degrees. TheCaI422.6nmlineincreasedin%pbymid-eclipse(peakpolarization>1% centered at the line rest wavelength. The polarization increased frommid-throughthelateeclipseandbroadenedonthebluewardsideastheblueabsorptioncomponentappearedinthespectra. Thequ-plot(Figure9)correspondingtomid-eclipsemaybecomplicatedbythepresenceofapossibleblendedline.Thelinecorecorrespondsto(–%q,+%u;greendiamonds),theexcursionof(+%q,+%u;redtriangles)correspondstotheredabsorptionwing(apossibleblend)andtheblue-shiftedabsorptioncorrespondsto(–%q,–%u;bluesquares).Asimilarscenariocorrespondstothelateeclipsequ-plot,withthenotableexceptionthatthedegreeofpolarizationhasobviouslyincreasedforthelinecenterat(–%q,+%u;greendiamonds). The%pdecreasedafter4thcontactandthelinereturnedtoitspre-eclipseshape.Thelinearpolarizationexhibitedtwopeaksin%p,onecenteredontheFstarandtheotheroffsetfromtheFstarvelocitybyabout+50kms–1,centeredonthepresumedTiIIfeature.Thequ-plot(Figure9)describestwodominantposition angles for the line in post eclipse; the excursion of (–%q; greendiamonds)correspondstothelinecoreandtheexcursion(+%q;redtriangles)correspondstotheredwing. WeexaminedotherCaI lines todiscover if thepolarizationbehaviorofthegroundstatetransitionwasconsistentwithotherenergytransitionsofthisatomicspecies.AnotherCaIline(restwavelength430.774nm)arisesfromahigherenergylevel(1.9eV)andexhibitedsimilarlineprofilechangesduringeclipse, however, there were insufficient data points corresponding to p/σ ≥ 4 to comparepolarizationchangesofthislinewithchangesobservedinthegroundstateCaIline.WeobservednolinearpolarizationsignaturesinotherCaIlinesofcomparableenergytransitionlevelstotheCaIlineat430.774nm. ThepolarizationbehaviorofthislinesuggeststhatCaI(422.6nm)tracespolarizationassociatedwiththeFstaritself,aswellasdiskeffects.Kim(2008)noted a 67-day out-of-eclipse light variation. We speculate that the F starpolarizationfeaturesweobservedmightbeassociatedwithupwellingandlargescalebrightconvectiveregions.

4.8.CircularpolarizationandStokesV WeidentifiednosignificantStokesV(circular)polarizationsignalinanyofthespectrallineswehavedescribed.Ourpreliminaryassessmentisthattherearenosignificantcircularpolarizationfeaturesinthedataset.Thepresenceofcircularpolarizationsignaturescouldindicatethatmagneticfieldsarepresent


andcontributetopolarization;thelackofsignalsuggeststhatmagneticfieldsarenotamajorcontributortothepolarizationweobserved.

5. Results

Thepresenceofpersistentpolarization inspectral linessuchasH-alpha,H-beta, and the Ca I 422.6 nm line out-of-eclipse suggests that asymmetrypersistsintheFstarforextendedperiods.H-alphapolarizationwasidentifiedinESPaDOnSobservationsofeAurdatedFebruary7and8,2006(HarringtonandKuhn2009),atphase0.925,morethanthreeyearsbeforetherecenteclipseand about two years before periastron. Those observations, as well as theH-alphaobservationspresentedhere,indicatedthattheblueandredemissionwingsarenotpolarized,suggestingpossiblesymmetryintheemittingregion(attheseshiftedvelocities/temperatures),orinsufficientopticaldepthtogeneratedetectablepolarizationfromscatteringintheregion.WealsoobservedthattheH-alphalinedoesnotsaturate,unlikeH-betaandothersintheBalmerseries.This suggests that a broad emission exists, contributing additional H-alphaphotonstothelinecore. WeobservedthatH-alphaandH-betaexhibiteddifferentpositionanglesinpre-eclipse.TheH-betaabsorptionmay indicate thepresenceofequatoriallyalignedhydrogengas—theopticallythickcomponentscatteringat90degreesperpendicular to the optically thin component. The H-alpha polarizationpositionanglesmayincludeacomponentfrominterstellarpolarization,ortheymayindicateamorecomplexdistributionofhydrogengasat thoseenergies.Chadimaet al.(2011)demonstratedthattheatmosphereofthediskstartstobeprojectedagainsttheFstarasearlyasthreeyearsbeforethebeginningofthephotometriceclipse;ourobservationsseemtocorroboratetheirfindings. H-alpha and H-beta showed similar mid- and late eclipse behavior inqu-space.The linecoresandwingsseem toagreeabout the rangeofanglesinvolved,suggestingthatthedominantfeaturesarisefromthesameorientationinthesky(gaseousmaterialaboveandbelowthedisk).Anoffsetof90degreesbetween linecoreandabsorptionwings is consistentwith theeffectopacitymayhaveonscattering. The polarization behavior of the K I 769.9 nm line confirmed that thislinehasnoF-starcomponent;thelinemaybeconsideredabellwetherforlowexcitationlinesaffectedbythediskduringeclipse.Limbpolarizationcannotbethesolecontributortopolarizationsignaturesduringeclipse(forexample,Kempet al.1986)becausethislinecannothavealimbpolarizationcomponent.Thedisk exhibited significantly strongerpolarization features in late eclipsethan in any other eclipse epoch. Many observers have noted the asymmetryintheline(forexample,Leadbeateret al.2012).Theincreaseinpolarizationmay indicate that thedensityof scatteringmaterial increased in lateeclipse.PearsonandStencel(2012)notethe“dawn”faceofthediskmayrotateintothe


line-of-sightduringlateeclipseepochs.Thewarmed,presumablysublimated,materialcouldcontributetotheincreasedresonantscatteringintheline.Theposition angles of scattering in late eclipse deviate from strict equatorial orpolaralignment;modelingisrequiredtoreplicatethelate-eclipseStokes%qand%ubehavior. The pre-eclipse polarization features of the Ca I 422.6 nm line showedcontributions from the F star as well as from the eclipse. The increase inpolarizationinlateeclipseisconsistentwiththeKIlinebehaviorandmayalsosuggestanincreaseinthedensityofscatteringmaterial. Thespectralandlinearpolarizationfeaturespresentedhereareasampleofthefeaturespresentinthedataset.Onlyafewepochshavebeenpresentedforbrevity.WefoundsignificantchangestolinearpolarizationinlinessuchasH-alpha,H-beta,CaI422.6nm,andKI796.6nmpresentedhere.

6. Conclusions and next steps

The analysis present here is awork inprogress and is not a finalword.There are many spectral features whose linear polarization characteristicsremaintobedescribed.WeareoptimisticaboutthepotentialinthesedatatohelpcharacterizepolarizationfeaturesthatmaybeattributedtotheFstaritself,aswellasthepolarizationthatarisesfromtheeclipsingdisk.Ournextstepsinasubsequentpaperwillincludeidentificationandclassificationofspectralfeatures that exhibit polarization, an analysis of the position angle of linearpolarizationfeatures(tofullydescribe the linearpolarizationvector),andananalysisofscatteringbehaviorwhentheFstarisnotuniformlyeclipsed.7. Acknowledgements

TheauthorsaregratefulforsupportofthisworkinpartfromabequestinsupportofastronomyfromtheestateofWilliamHerschelWomble.BasedonobservationsobtainedattheCanada-France-HawaiiTelescope(CFHT),whichisoperatedbytheNationalResearchCouncilofCanada,theInstitutNationaldesSciencesdel’UniversoftheCentreNationaldelaRechercheScientiqueofFrance,andtheUniversityofHawaii.WewouldliketothankRobertoCasini,Elizabeth Griffin, Philip Judge, Brian Kloppenborg, Bruce Lites, and JanStenfloforhelpfuldiscussions. The authors are very grateful to the referee, John Landstreet, for manyhelpfulsuggestionsandimprovementstothework.


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Vaillancourt,J.2006,Publ. Astron. Soc. Pacific,118,1340.Welty,D.,andHobbs,L.2001,Astrophys. J., Suppl. Ser.,133,345.


2006-01-07 3774.93 0.926 2008-08-25 4704.04 0.019 2008-10-18 4757.92 0.025 2008-12-07d 4807.82 0.030 2008-12-08d 4808.83 0.030 2008-12-09d 4809.83 0.030 2008-12-10d 4810.83 0.030 2008-12-16 4817.05 0.031 2009-02-13 4875.71 0.036 2009-02-14 4876.70 0.037 2009-02-17 4879.85 0.037 2009-05-04 4955.72 0.045 1stcontact 2009-08-22 5060 2009-09-04 5079.05 0.057 2009-09-05 5080.07 0.057 2009-09-08 5083.15 0.057 2009-09-11 5086.11 0.058 2009-09-25 5100.05 0.059 2009-09-26 5101.02 0.059 2009-09-29 5104.03 0.060 2009-10-02 5107.02 0.060 2009-10-07 5112.01 0.060 2009-10-10 5115.16 0.061 2009-11-29 5165.11 0.066 2009-12-02 5168.00 0.066 2009-12-04 5169.80 0.066 2009-12-07 5173.14 0.067 2009-12-08 5174.14 0.067 2010-01-02 5198.77 0.069 2ndcontact 2010-01-02 5200 2010-01-26 5222.71 0.072 2010-01-28 5224.70 0.072 2010-03-08 5263.72 0.076 mid-eclipse 2010-07-06 5390 2010-07-23 5401.12 0.090 2010-08-01d 5410.13 0.090 2010-08-05d 5414.11 0.091 2010-10-16 5485.91 0.098 2010-10-18 5487.90 0.098 2010-10-19 5488.99 0.098


Table1.Logofobservations. Commenta Gregorian RJDb Phasec


2010-10-21 5490.93 0.099 2010-11-15 5516.02 0.101 2010-11-16 5517.14 0.101 2010-11-17 5517.96 0.101 2010-11-22d 5522.89 0.102 2010-11-24d 5524.99 0.102 2010-12-19 5549.74 0.105 3rdcontact 2011-03-18 5620 4thcontact 2011-05-21 5720 2011-08-17 5791.13 0.129 2011-11-01 5867.13 0.137 2011-11-15d 5880.99 0.138 2011-11-16d 5882.16 0.138 2012-01-06 5933.00 0.143 2012-01-17 5943.78 0.144Notes: aRJD for eclipse taken from Stencel etal. (2011); bJulian date—2450000; cTime of periastron and period from Stefanik etal. (2010) 2434723+9896.0E; dEpoch binning as follows: early—binned 20081207, 20081208, 20081209, 20081210; mid—binned 20100801 and 20100805; late—binned 201122 and 20111124; post—binned 20111115, 2011116.

Table1.Logofobservations,cont. Commenta Gregorian RJDb Phasec

Figure1.TimeseriesofH-alpha(656.280nm)lineand%pprofilesforpre-,mid-,andlate-eclipseepochs.Velocityiscenteredonthelinerestwavelength.TheF-starradialvelocityisindicatedbyastarsymbol.Notethestarisslightlyred-shiftedpre-eclipseandblue-shiftedlateeclipse.Polarizationdataareepoch-(seetext)andwavelength-binned(binsize0.015nm).Averageerrorsin%pareshown.


Figure2.QU-plotsofH-alpha(656.280nm)forpre-,mid-,late,andpost-eclipseepochandwavelengthbinneddata.Thefirstdateofeachbinnedepochisgiven.Averageerrorbarsareshown.NotetheQU-plotisnearlylinearinpre-eclipse.Theprominentexcursion(–%q,–%u;greendiamonds)correspondstothelinecore(±25kms-1).Absorptionwingcontributionsappearinmid-andlate-eclipse.Thebluewingcorrespondsto(+%q,+%u;bluesquares)andtheredwingcorrespondsto(+%q,–%u;redtriangles)inmid-eclipse.Bylateeclipse,theredwingpolarizationhaslargelydisappeared(near0,0)andthelarge+%qexcursionisbluewingpolarization.Thelinecorepolarizationis(+%u,–%q;greendiamonds)inposteclipse.Thesedatahavebeenrotatedintothestellarframe(seetextfordescription).

Figure 3. Position angle calculated for (%q, %u) pairs for the H-alpha line in mid-eclipse.Thedataare rotated to thestellar frameandunbinned.Notice that the linearpolarization position angle appears randomly scattered outside of the line, which isexpected.Thepositionangles thatcorrespondto the linecore(±25kms–1 fromrestwavelength) are plotted in green; position angles corresponding to the blue-shiftedabsorptionwing(–125kms–1to–25kms–1)areplottedasbluestar-shapes;andpositionanglescorrespondingtothered-shiftedabsorptionwing(+25kms–1to+125kms–1)areplottedasredstar-shapes.Positionanglesonlyrangefrom0° to180°becauseof thenatureoftheStokesparameters;apositionangleof180°isconsistentwith0°.Noticethelinecorepolarizationisoffsetbyabout90°fromthewings.Thismaybeanopacityeffect.Comparethesedatatothemid-eclipseQU-plot(Figure2)andmid-eclipselineprofile(Figure1).


Figure4.TimeseriesofH-beta(486.135nm)lineand%pprofilesforpre-,mid-,andlate-eclipseepochs.Velocityiscenteredonthelinerestwavelength.TheF-starradialvelocityisindicatedbyastarsymbol.Polarizationdataareepoch-(seetext)andwavelengthbinned(binsize0.015nm).Averageerrorsin%pareshown.Thelineisclearlysaturatedinlateeclipse,fallingtojust1.6%intensityatthedeepestpointand,althoughS/N is nearly 200 here, the ratio p/σ is only1.2;therefore%p=0.Theratiop/σ ranges from 3 to 11 for %p > 0.4 outsidethesaturatedregion.

Figure5.QU-plotsofH-beta(486.135nm)forpre-,mid-,late-,andpost-eclipseepoch-andwavelength-binneddata.Thefirstdateofeachbinnedepochisgiven.Averageerrorbarsareshown.Absorptionwingcontributionsappearinmid-andlate-eclipse.Thebluewingcorrespondsto(+%q,+%u;bluesquares)andtheredwingcorrespondsto(+%q,–%u;redtriangles)inmid-eclipse.Linecoreis–%q(greendiamonds).Bylateeclipse,theredwingpolarizationhasdisappeared(centeredon0,0)andthelarge+%qexcursionisbluewingpolarization(bluesquares).Thelinecorepolarizationis+%uinposteclipse.Thesedatahavebeenrotatedintothestellarframe(seetextfordescription).


Figure6.TimeseriesofaKI(769.896nm)lineand%pprofilesforpre-,mid-,andlate-eclipseepochs.Velocityiscenteredonrestwavelength.Polarizationdataareepoch-(seetext)andwavelength-binned(binsize0.015nm).Theout-of-eclipselineisthoughttohaveaninterstellarorigin.Notethestarisred-shiftedpre-eclipse,butthelinecoreisnotred-shiftedandthelineexhibitsnopolarizationfeatures.Diskcontributionstothelineinlateeclipseareblue-shiftedandexhibitpolarizationfeatures.

Figure7.QU-plotsofKI(769.896nm)forpre-,mid-,late-,andpost-eclipseepoch-andwavelength-binneddata.Thefirstdateofeachbinnedepochisgiven.Averageerrorbarsaregiven.Theout-of-eclipselineisthoughttohaveaninterstellarorigin(forexample,WeltyandHobbs,2001).Notetherearenopolarizationfeaturespre-eclipseorposteclipse.Diskcontributionsappearaftermid-eclipse.The(–%q,+%u;bluesquares)excursioncorrespondstotheblue-shiftedabsorptionwing.Thesedatahavebeenrotatedintothestellarframe(seetextfordescription).


Figure8.TimeseriesofaCaI(422.673nm)lineand%pforpre-,mid-,andlate-eclipseepochs.Velocityiscenteredonthelinerestwavelength.Thislinecorrespondstoagroundstatetransition.Notethedramaticincreaseinlinearpolarizationinlaterepochs.Thedataareepoch-(seetext)andwavelength-binned(binsize0.015nm).Averageerrorsin%pareshown.

Figure9.QU-plotsofCaI(422.673nm)forpre-,mid-,late-,andpost-eclipseepoch-andwavelength-binneddata.Thefirstdateofeachbinnedepochisgiven.Averageerrorbarsareshown.Absorptionwingcontributionsappearinmid-andlate-eclipse.TheQU-loop(greendiamonds)largelycorrespondstolinecore,withsmallredwingcontributionsin+%qinmid-eclipse(redtriangles).Bylate-eclipse,theQU-loophasgrownwithsmall–%qcontributionsfromthebluewing(bluesquares)and+%qcontributionsfromtheredwing.The“flattened”QU-loopcorrespondstolinecore(greendiamonds)inposteclipse.Thesedatahavebeenrotatedintothestellarframe(seetextfordescription).

Cole, JAAVSO Volume 40, 2012 787

Polarimetry of e Aurigae, From November 2009 to January 2012

Gary M. ColeStarphysics Observatory, 14280 W. Windriver Lane, Reno, NV 89511; [email protected]; www.starphysics.com

Received March 20, 2012; revised May 17, 2012; accepted June 25, 2012

Abstract During the 2010–2012 eclipse of eAurigae, the author obtainedlinearpolarizationmeasurementsduring200nightsofobservationoverthreeobservingseasons.Theseobservationsbeganbeforesecondcontactandhaveextended some six months into the post-eclipse period. Measurements weremade in V, B, and R photometric bands. The polarization of eAurigae wasobservedtovarybynearly0.6%peaktovalleyduringthisperiodincyclesofvaryingduration.Thesevariationsresemble,ataqualitativelevel,thoseseenbyKempandHensonduringthe1984eclipseegress.Inparticulartheyshowevidenceoflocalpolarizationactivityextendingwellpast4thcontact.

1. Introduction

eAurigae is an F-type supergiant star approximately 2,000 light yearsdistant.Normallyseenatmagnitude3,itundergoesan18-month-longeclipseevery27years.Thesecondaryobjectactsasanopaquedisk,partiallycoveringtheprimary,whichdimsthesystem’slightbyapproximatelyonemagnitude.Whilethediskisassumedtocontainahotembeddedstar,thespectrumofthesecondaryhasnotbeenobserved. At the suggestion of Dr. Robert Stencel (University of Denver) in May2009,theauthorbeganaseriesofbroadbandpolarimetricobservationsofeAurduring its recenteclipse.Thepurposewas toextendmeasurementsobtainedduringthe1984eclipsebyDr.JimKempandcolleagues(Kempet al.1986)andfollowedupbyhisstudent,Dr.GaryHenson(Henson1989). Those observations had revealed significant variations in polarizationduring and after the eclipse. Dr. Stencel suggested that similar observationsduringtherecenteclipseshouldbeusefulforcomparison. Observationsreportedhereinweremadeoverthecourseofthreeobservingseasons. Season 1 from November 2009 to February 2010, season 2 fromSeptember2010toMay2011,andseason3fromJuly2011intoJanuary2012.Ongoinginstrumentdevelopmentledtosignificantimprovementsinthequalityofmeasurementsoverthecourseofthiswork.

Cole, JAAVSO Volume 40, 2012788

2. Instrumentation

There are no commercial sources for small telescope astronomicalpolarimeters.Myinstrumentshavebeenpurpose-builtforthisprojectfollowingthe general concepts used on the Hawaii 88-inch telescope as described inMasieroet al.(2007). An imaging telescope becomes a dual beam polarimeter with theintroduction of a rotating half wave retarder and a calcite beamsplitter.Thewaveplatematerial used is an achromaticpolymerof the same specificationasintheHawaiiinstrument.Thebeamsplitterisa13-mmcalciteSavartplatefabricatedbyHalboOptics,whichprovidesaseparationof1mmattheCCDfocal plate.This is approximately 135arcseconds at the plate scale used ontheC8telescopeand55arcsecondsontheC14.Thisismorethanenoughtocleanlyseparatetheslightlydefocusedandastigmaticstarimages.Theinitialwaveplate rotator was constructed with a USB-controlled servo motor andplasticgearing. TheSavartplateandafocalreducerweremountedintothenoseofanSBIGST6camera.Therotator,BVRfilterselector,andcamerawereattachedtoaC8opticaltubeandtheentireassemblywasmountedontoanexistingautomatedC14telescope. Thisarrangementwasusedforthefirstseasonofobserving.Forthesecondseason, the camera was replaced with a SBIG ST402 camera. This greatlyreduced thermal noise and reduced download time. The rotator, which hadfrequentbreakdownsandpoorgearing,remainedinuseuntilFebruaryof2010whenitwasreplacedwithahighprecisionrotatorengineeredbyOptec,Inc. Forthefinalseasonofthiswork,theinstrumentwasreconfiguredtoworkin the C14 optical system.The waveplate rotator was mounted between thefocuserandtheexistingfour-wayinstrumentselector.AdoublefoldorthogonalmirrorassemblyrelaysthebeamintotheSavart+cameraassembly. These ongoing changes have yielded significant improvements in dataqualityoverthecourseofthisproject.Inthefirstseasonofmeasurements,theuncertainty, ∆p, in the degree of linear polarization was ~ ∆p ± 0.1%; in the second season this was improved to ~ ∆p ± 0.05%, and further refined to ~ ∆p ±0.03%inthethird. Note: The Johnson BVR photometric filters are used in series witha 400-700nm luminance filter so as to match the effective range of theachromaticwaveplate.ThisresultsinaslightlyreddenedBandaslightlytruncatedRbandpass.

3. Calibration

APolarimetercanexhibitsystematicerrordueto1)instrumentalpolarization,2)co-ordinateframemiss-alignment,and3)modulationinefficiency.


Instrumentalpolarizationisdetectedbyobservingzeropolarizationstandardstars.Severalhundredmeasurementsofsuchstarsindicatethatsuchinstrumentaleffects, if present, are less than 0.03% and show no preferred orientation. Theangleofpolarization,q, isdefinedby IAUconventionsasananglefromtheNorth-Southline,towardsEast.Themeasuredangle,therefore,mustbeadjustedsoastomaintainthisconvention.Thefirstlevelofadjustmentistosetthe“zeropoint”ofthewaveplatetoreplicatetheconvention.Thiswasdoneusinganexternally-mountedsheetpolarizerorientedalongthedeclinationaxis.Asecondstepwastorefinethefiduciaryanglebyusingmeasurementsofstandardstars. Inpractice, theauthorhas found itverydifficult tomaintain theangularprecision of the instrument over the course of these observations. Frequentrotatorbreakdowns,mechanicalrotation,andreconfigurationshavedisturbedtheeffectivealignmentandhencethereportedangles.Frequentobservationsof HD 21291, whose stability was affirmed from HPOL measurements (U.Wisconsin2012),wereusedforangularcorrection. The modulation efficiency was checked by comparing large sets ofinstrumentalresultswithcatalogvaluesforstarsofknownhighpolarization.Theresultsobtainedmatchexpectedvalueswithintheexperimentaluncertainties.Nocorrectionsformodulationefficiencyhavebeenmade.

4. Observing procedure

Anautomatedprocedurehasbeendevelopedforcollectingandreducingthedataforeachmeasurementandpostingtheresultstoasummaryfileforthatobject.Adetailedcalculationreportandalldatafilesareretained. Thetelescopeisslewedtothetarget.Afilterisselectedandaninitialimageframeistaken.Theimageisdark-subtractedandthetargetstarpairislocated. Anappropriateexposuretimeiscalculatedbaseduponthemaximumpixelleveloftheoriginalimage.Threedarkimagesareobtainedfromwhichamediandarkimageisassembled.Thesystemthencollectsfromfourtoeightdatasets,eachconsistingoffourdataframestakenatdifferentwaveplatepositions.Eachframeisdark-subtractedusingthemediandarkfortheseries. Theentiresequenceisrepeatedusingashorterexposuretimeifanypixelinanyimageexceedsapresetsub-saturationthreshold. Theoriginalrotatorwassteppedthroughangularpositionsof0,22.5,45,and67.5degreesforeachsetbecausemovinginaconsistentdirectionminimizedgearerrors.Oncethenewrotatorwasinstalledtheimagesweretakenin0,45,22.5,67.5ordersothatthepairsofimagesusedtodetermineeachofthetwoStokesparametersweretakenascloselyintimeaspossible.Thewaveplatewasthensteppedby90degreesforeachsubsequentdatasettominimizetheeffectsofanyirregularitiesintheangularsettingofthewaveplate.


5. Data reduction

A floating square aperture that is aligned to the centroid of each star issizedtocapture97.5%ofthetotalsignalonthefirstframe.Thisaperturesizeisthenusedforallimagesinthedataset.Alargerconcentricapertureisusedto estimate thebackground signal.Thedualbeammethod is self-calibratinganddoesnotrequireflatfielding,butthisissubjecttotherequirementthatthestarimagesarerecordedontothesamepixellocationswithineachdatapair.Tomaintain this requirement,anydatasets thathaveexcessivemotionbetweenframesareexcludedfromcalculations. Once the intensity values have been extracted from all data sets of theobservation, thedegreeofpolarizationandanglearecomputedaccording tothemethodsofTinbergen(1996).Thesamearecalculatedforeachindividualdatasetforcomparison.TheerrorthatcanbeascribedtophotonstatisticsiscalculatedaccordingtothemethodofSerkowski(1974). The polarization value is adjusted for zero point bias according to themethoddescribedbyClarke(2010).Thevalueofthisadjustmentistypicallylessthan0.01%forourobservationsandinsignificantintermsoftheuncertaintyassociatedwitheachmeasurement;theS/Nratioishighandthevalueofpislargerelativetothemeasurementuncertainties.6. Target observations

In Table 1 the result for 200 nights of observation are presented. Eachmeasurement consists of multiple sets of four images taken at waveplatepositionsof0,22.5,45,and67.5degrees.Onmanynights inwhichseveralmeasurementswereobtained,thesehavebeenaveraged.Theerrorsestimatedfor each polarization measurement are stated in the adjoining columns.Theanglesareshownintherightmostthreecolumns.Theerrorsassociatedwiththeanglesarediscussedinthenextsection.

7. Sources of uncertainty

ObservationspriortoMarchof2011weresubjecttoimprecisewaveplatepositioning.Theoriginal rotatingdeviceusedplasticgears to translateservomotion.Aseachcogofthemaingearcorrespondstonearly3degrees,asmallrangeofrandomvariationisinevitable.Therewasalsoaninfrequentproblemof“hopping.”According to theanalysisdonebyRamaprakashet al. (1998),anyuncertaintyofangularpositioninggeneratesapolarizationuncertaintyofsimilarmagnitude.Henceifa±1degreeerroractuallyoccurredfromtimetotime,itwouldadd0.05%totheuncertaintyofanindividualmeasurement.Thissourceofthisproblemwasreducedbyatleastafactorof25whentheOptecRotatorwasinstalledlateinseason2.


Observations from this site encounter significant turbulence, bad seeing,windbuffeting,andimperfectguiding.Theeffectsofseeingaretomovethecenterofilluminationandtochangethedistributionoflightwithineachstarimage.Thesefactorsinducesmallrandomerrorsintotheresultsthataredifficulttoquantify.Anexaminationofthereportedvariationsinclosely-spacedtimesequentialmeasurementssuggest that thedatacarryerrorabout50%greaterthanpredictedsimplyfromthephotonflux. For the data presented in this paper, the errors reported in the table andchartsforeachmeasurementaredoublethosecalculatedbaseduponthephotonstatisticsoftheactualimages.Theauthorbelievesthisprovidesaconservativeestimateofthetrueuncertaintyintotalpolarization. Theuncertaintyinreportedanglesofpolarizationismuchworsethatthatofthemagnitudeofpolarizationbecause1)itisderivedfrommeasurementsofstandardstarswhichhaveatleastequivalentuncertainty,and2)becausetherewerefrequentmechanicaladjustmentsmadeduringthecourseofobservations.Theauthorbelievesthattheanglesreportedcontainbothrandomandsystematicerrorsthatmayreachthelevelof±1degree.

8. Discussion

The polarization measurements (%) in the BVR photometric bands areplottedasatimeseriesinFigure1.Thefirstseasonofobservationscoversthetimeapproachingthesecondcontactduringtheeclipse.Thepolarizationvalues(p)arehighandarematchedagainintheearlypartofthesecondhalfofthesecondseasonleadinguptotheendoftheeclipse.Thethirdobservingseasonisbeyond theeclipsephaseandshowsstrongpolarizationactivitywith fallsandrecoveriescoveringseveraltensofdayswithamplitudesmuchthesameasduringtheeclipse.Particularlyontheprotractedfallofsome70daysatthebeginningofthesecondseason,soonaftermid-eclipse,thecolordependenceofthepolarizationclearlyshowsinFigure1,withthevaluesofpfallingfromBthroughVtoR. Figure2displayspandthepositionangle,q,fortheVbandoverthethreeseasons.Thereappears tobeacorrelationbetween the threepeaksofpandtroughsinqduringthesecondseason,but this isnotquiteasapparentpost-eclipse.Thisbehavior indicates that thevariable intrinsicpolarization isatasignificantangletothatofthelargeinterstellarcomponent. Several researchers, including the teamat thePineBluffObservatoryoftheUniversityofWisconsin,havemadesynoptic,out-of-eclipseobservationsofthisbinarysystem.During1990to1996,theirmeasurementsrevealedp(V)valuesvaryingfrom1.96%to2.06%withq(V)~144degrees.Thisweassumetobetheinterstellarcomponent. Figure3displaysthenormalizedStokesparametersqanduasafunctionof time. Direct comparison of the polarimetric behavior of this eclipse with


thatreportedbyKempet al.(1986)ofthepreviousonecannotbemadeastheearlierauthorsprovidenormalizedStokesparameter time-lineplotswith theq,uvaluesexpressedinaco-ordinateframeat5degreesrelativetothestandardequatorialsystem.However,astheangulardifferencebetweenframesisverysmall,strongqualitativecomparisonscanbemade. Inparticular,thebehaviorofbothqanduduringtheegressphaseisextremelysimilar with small oscillations in q and a smooth rise in u in both data setsfollowedbyarapiddecline.Themagnitudeandfrequencyofvariationinbothdatasetsshowconsiderablesimilaritybutnotdirectrepetitionexceptategress. A standard method for investigation of polarimetric data is to plot thenormalizedStokesparametersq,uasCartesianco-ordinates.ThishasbeendoneinFigure4foralltheV-banddata.Althoughthescatteroftheplottedpointsisverylarge,simpleinspectionshowsthatthereisatrend.Thisbecomesmorereadily apparent when the data are grouped into smaller temporal segmentsas has been done in Figure 5.While each segment has a different origin intheq,u-plane,theslopesduringthesefourselectedtimeintervalsareclosetobeingparallel.ThisisshownmoreclearlyinFigure6wherethefoursegmentsareoverlaid.Translatingthesegradientsintocelestialangles,thepolarizationalmovementappearsalongpositionanglesbetween7and22degrees.Giventheleveloferrorintherawdata,thesevaluesareclosetothat(5degrees)takenbyKempet al.(1986)fromtheastrometricdataofvandeKamp(1978)asbeingrelatedtotheorbitalplanedirectionprojectedontothesky.TheuncertaintyofthisangleisnotgivenbyKempet al.(1986)anditisdifficulttoascertainthebestvaluefromthesketchprovidedbyvandeKamp(1978).Asthetrendanglesareclosetotheestimateoftheorbitalprojectionangle,short-termpolarizationchanges, chiefly affecting theqvalues, canbe surmised asoriginating fromscatteringbyclumpymaterialintheorbitalplane.Thedriftsmaybeaffectedbyintroductionofnewclumpsandtheirdecay,orbychangesintheirdistancefromtheilluminatingstar.Astowhytheoriginofthetrendlinesmovesaboutto produce the more blurred picture that Figure 5 presents, with significantchangesintheuparameter,amoresophisticatedmodelisrequired. Finally,thereappearstobecorrelationhoweverbetweenseveraloftheUbandphotometricmaximaoftherecenteclipse(eAurcampaign2011)andthepolarimetricmaximainthesedata.Inparticular,atJD2455460,atJD2455545,andategressthevaluesofUandpseemtomovetogether.

9. Future work

In future seasons it is the author’s intention to monitor the system inthe same frequentmannerasduring theeclipse toconfirm thenatureof thevariabilityandsearchforshort-termperiodicities.AsimultaneousprogramofUandBphotometrywillbeaddedtosearchforanydirectcorrelationbetweentheopticalandpolarimetricvariability.



Theauthorextendshis thanks toDr.RobertStencelof theUniversityofDenver,withoutwhosethoughtfuladviceandencouragementthisprojectwouldnothavebeencompleted.AlsothankstoDr.StencelforkindlyprovidingacopyofHenson(1989). ThanksalsotoBolderVisionOptik,ofBoulder,Colorado,forthewaveplatematerialsandtoOptec,Inc.,Lowell,Michigan,forthedesignandfabricationofthewaveplaterotator. ThisresearchhasmadeuseoftheSIMBADandVizieRdatabasesoperatedatCDS,Strasbourg,FranceandofNASA’sAstrophysicsDataSystem. TheauthoracknowledgestheCitizenSkyprojectof theAAVSOandtheNationalScienceFoundation.

References

Clarke,D.2010,Stellar Polarimetry,Wiley-VCH,Hoboken,NJ.eAurigaecampaign.2011,http://www.hposoft.com/Plots09/UBBand.jpg.Henson,G.D.1989,Ph.D.dissertation(September),Univ.Oregon.Kemp,J.C.,Henson,G.D.,Kraus,D.,Beardsley,I.,Carroll,L.,Ake,T.,Simon,

T.,andCollins,G.1986,Astrophys. J., Lett. Ed.,300,L11.Masiero,J.,Hodapp,K.,Harrington,D.,andLin,H.2007,Publ. Astron. Soc.

Pacific,119,1126.Ramaprakash,A.N.,Gupta,R.,Sen,A.K.,andTandon,S.N.1998,Astron.

Astrophys., Suppl. Ser.,128,369.Serkowski, K. 1974, in Planets, Stars, and Nebulae Studied With

Photopolarimetry, ed. T. Gehrels, Proc. IAU Collq. 23, Univ. ArizonaPress,136.

Tinbergen, J. 1996, Astronomical Polarimetry, Cambridge Univ. Press,Cambridge,100.

Univ.Wisconsin,SpaceAstronomyLaboratory.2012,HPOLspectropolarimeterwebsite(http://www.sal.wisc.edu/HPOL/).

VandeKamp,P.1978,Astron. J.,83,975.

2455145 2.474 0.07 — — — — — — —2455150 2.482 0.05 — — 2.381 0.1 — — —2455151 2.307 0.09 — — — — — — —2455154 2.259 0.11 — — 2.22 0.04 — — —2455155 2.454 0.14 — — 2.396 0.05 — — —


Table1.ObservationsofeAurigaepolarizationfromJD2455145to2455944inV,B,andRphotometricbands. JD V %Pol %Err B %Pol %Err R %Pol %Err V q B q R q



2455159 2.357 0.09 — — 2.334 0.1 — — —2455168 2.145 0.05 — — 2.147 0.09 — — —2455169 2.249 0.04 — — 2.206 0.07 — — —2455191 2.218 0.1 — — — — — — —2455201 2.201 0.14 — — — — — — —2455202 2.112 0.08 — — 2.208 0.09 — — —2455210 2.287 0.08 — — 2.271 0.07 — — —2455211 2.314 0.1 — — 2.246 0.14 — — —2455212 2.325 0.09 — — — — — — —2455220 2.271 0.04 2.299 0.06 — — — — —2455449 2.168 0.06 2.232 0.06 2.104 0.06 139.8 138.7 140.92455450 2.197 0.06 2.192 0.06 2.136 0.06 140.2 139.1 141.22455451 2.194 0.07 2.209 0.07 2.239 0.07 139.6 140.1 139.32455452 2.212 0.07 2.236 0.06 2.18 0.07 139.1 138.3 140.92455453 2.233 0.05 2.223 0.05 2.166 0.06 139 138.3 140.82455454 2.238 0.07 2.233 0.06 2.148 0.07 139.5 138.4 141.12455455 2.176 0.04 2.215 0.03 2.132 0.04 139.3 138.7 141.32455456 2.208 0.04 2.225 0.04 2.193 0.04 138.9 138.9 139.52455458 2.222 0.05 2.293 0.05 2.183 0.05 139.2 138.2 141.32455462 2.244 0.06 2.27 0.06 2.138 0.06 139.2 138.3 140.62455463 2.193 0.05 2.264 0.04 2.136 0.05 139.1 137.7 140.72455464 2.246 0.06 2.262 0.05 2.309 0.06 139 138.8 139.12455465 2.142 0.06 2.197 0.06 2.189 0.06 138.8 138.2 138.42455467 2.218 0.05 2.283 0.05 2.203 0.05 139.4 138.4 140.82455468 2.222 0.06 2.243 0.05 2.144 0.08 139.9 139 141.32455469 2.188 0.06 2.198 0.06 2.179 0.06 138.9 137.6 140.72455470 2.144 0.07 2.191 0.06 2.085 0.07 139.6 138.9 141.22455478 2.154 0.05 2.171 0.05 2.117 0.06 141 139.9 1432455479 2.12 0.06 2.193 0.05 2.127 0.06 141.2 140.3 142.32455480 2.118 0.07 2.105 0.07 2.119 0.06 140.5 140.7 140.72455481 2.125 0.06 2.135 0.06 2.07 0.06 141.2 139.9 142.72455482 2.13 0.07 2.149 0.07 2.117 0.07 141.8 140.5 143.12455483 2.142 0.06 2.142 0.06 2.097 0.07 141.8 140.8 143.52455484 2.133 0.06 — — 2.168 0.07 142 — 142.92455485 2.148 0.06 2.154 0.06 2.119 0.06 140.9 140.3 142.82455489 2.114 0.06 2.101 0.06 2.068 0.07 142 140.8 142.52455490 2.103 0.05 2.126 0.06 2.184 0.05 140.6 140.8 140.12455501 2.152 0.04 2.1 0.03 2.085 0.03 141.16140.56 142.362455502 2.083 0.04 2.113 0.04 2.015 0.04 141.8 141.4 143.1

Table1.ObservationsofeAurigaepolarizationfromJD2455145to2455944inV,B,andRphotometricbands,cont. JD V %Pol %Err B %Pol %Err R %Pol %Err V q B q R q


2455503 2.093 0.05 2.127 0.04 2.05 0.06 142 141.2 143.82455504 2.082 0.05 2.057 0.05 2.044 0.07 141.4 141 142.72455505 2.083 0.06 — — — — 141.8 — —2455507 2.063 0.04 2.065 0.03 2.029 0.04 140.8 140.1 142.92455509 2.083 0.05 2.081 0.07 2.076 0.06 142.2 141.8 1452455512 2.042 0.06 2.029 0.05 1.993 0.05 142.6 142 144.72455513 2.036 0.06 2.031 0.06 1.962 0.06 141.9 140.7 143.62455514 2.063 0.07 — — 2.041 0.09 141.2 — 142.92455515 2.111 0.08 2.043 0.07 2.004 0.07 141.2 141.6 143.42455516 2.1 0.06 2.025 0.05 2.022 0.06 141.2 140.4 142.52455517 2.061 0.06 2.045 0.06 2.026 0.06 141 141 142.32455518 2.031 0.06 — — — — 141.8 — —2455532 2.225 0.06 2.189 0.04 2.186 0.05 140 139.9 141.92455537 2.234 0.06 2.266 0.06 2.214 0.06 138.1 137.5 138.72455542 2.278 0.07 2.328 0.06 2.158 0.07 145.1 146 146.52455543 2.262 0.05 2.285 0.04 2.205 0.04 137.1 136.4 138.42455547 — — — — 2.175 0.06 — — 138.82455554 2.246 0.08 2.219 0.05 2.146 0.07 137.4 136.1 1402455555 2.246 0.06 2.243 0.06 2.174 0.06 137.3 136.3 139.32455558 2.154 0.07 2.199 0.06 2.207 0.08 138 136.9 140.72455565 2.115 0.05 2.15 0.05 2.091 0.05 139.7 139.5 141.62455566 2.122 0.05 2.124 0.05 2.021 0.05 138.7 137.8 140.72455567 2.122 0.06 2.104 0.05 2.064 0.06 138.4 137.6 140.22455568 2.113 0.05 2.102 0.04 2.015 0.05 139 138.2 140.92455569 2.149 0.05 2.112 0.06 2.088 0.05 138.3 138.5 1392455570 2.16 0.04 2.113 0.04 2.101 0.04 140.2 139.4 142.82455576 2.198 0.07 2.223 0.06 2.194 0.07 139.6 139.1 141.32455577 2.316 0.06 2.342 0.04 2.297 0.06 140.1 140.7 141.72455578 2.355 0.06 2.239 0.05 2.262 0.06 141.3 140.2 141.22455579 2.278 0.06 2.221 0.06 2.197 0.06 140.8 140.2 142.32455581 2.304 0.07 2.257 0.06 2.281 0.06 141.2 140.7 142.32455582 2.316 0.06 2.297 0.05 2.243 0.06 141 140.6 141.52455583 2.336 0.06 2.289 0.05 2.307 0.06 140.7 140.9 142.72455584 2.293 0.06 2.274 0.06 2.246 0.05 140.5 140.1 142.92455587 2.355 0.07 2.269 0.06 — — 140.6 140.2 —2455588 2.297 0.06 2.24 0.05 2.232 0.06 139.9 140.1 141.32455589 2.281 0.05 2.277 0.06 2.228 0.06 140.2 139.9 142.52455593 2.312 0.06 2.332 0.06 2.27 0.06 139.7 139.3 142.12455595 2.257 0.07 2.192 0.06 2.394 0.06 138.4 138.2 140.6




2455596 2.359 0.07 2.367 0.07 2.229 0.07 137.8 138.8 139.62455597 2.362 0.06 2.343 0.05 2.3 0.05 138.4 138.1 139.32455599 2.372 0.06 2.385 0.05 2.253 0.06 137.5 137.5 139.62455600 2.425 0.05 2.385 0.04 — — 137.7 137 —2455602 2.405 0.08 2.463 0.06 2.34 0.06 136.3 134.9 137.72455615 2.298 0.08 2.338 0.07 2.278 0.06 136.65137.35 136.452455616 2.312 0.05 2.289 0.03 2.264 0.04 137.15137.45 137.052455620 2.177 0.05 2.192 0.04 2.159 0.04 138.75138.85 138.552455621 2.184 0.07 2.193 0.04 2.221 0.05 138.85139.15 138.252455629 2.008 0.06 1.995 0.05 1.961 0.08 140.65141.15 139.352455630 1.971 0.04 1.971 0.04 1.949 0.05 140.31141.41 139.812455632 2.03 0.06 — — — — 139.21— —2455633 1.946 0.04 1.922 0.03 1.914 0.04 141.03141.23 140.732455638 1.913 0.07 — — 1.873 0.06 145.13— 145.132455643 1.872 0.07 1.9 0.06 — — — — —2455649 1.975 0.08 1.971 0.05 2.002 0.06 141.24141.14 140.542455651 2.019 0.05 1.988 0.05 2.012 0.05 143.04142.94 142.242455652 2.025 0.04 1.983 0.05 2.013 0.05 141.93142.03 140.832455653 1.979 0.07 2.011 0.06 1.991 0.08 139.63141.73 140.032455654 1.99 0.04 1.959 0.04 1.979 0.04 141.93141.93 140.832455655 1.978 0.07 2.003 0.09 2.005 0.08 141.73143.03 141.132455656 2.005 0.07 1.977 0.06 1.953 0.08 142.83143.53 141.532455657 1.994 0.08 2.01 0.07 2.006 0.07 144.13144.93 144.232455659 2.031 0.05 2.014 0.03 2.028 0.05 142.43141.73 141.932455661 1.96 0.07 — — — — 147.93— —2455662 2.011 0.07 1.996 0.08 2.037 0.06 141.98142.38 140.382455663 2.017 0.05 2.03 0.05 2.02 0.05 142.38141.88 140.682455665 2.021 0.03 2.008 0.04 — — 142.38141.68 —2455667 1.997 0.05 2.017 0.08 — — 141.38142.08 —2455670 1.959 0.08 1.924 0.06 — — 141.58140.98 —2455673 1.937 0.08 — — — — 140.68— —2455676 2.024 0.05 2.048 0.06 — — 139.68140.38 —2455678 2.025 0.05 1.925 0.07 — — 140.98140.88 —2455679 2.058 0.07 2.004 0.07 1.988 0.06 140.98140.58 140.182455682 2.034 0.06 2.004 0.06 2.004 0.06 141.58141.68 141.982455683 2.036 0.09 2.035 0.1 2 0.11 140.58144.28 139.682455684 2.005 0.09 2.069 0.07 — — 142.38141.08 —2455685 1.99 0.06 2.034 0.06 2.025 0.07 142.08141.58 141.482455686 2.017 0.07 — — — — 141.18— —




2455687 2.118 0.06 — — — — 141.28— —2455762 — — 2.111 0.04 2.026 0.04 — 144.5 146.62455765 2.108 0.03 2.133 0.03 — — 145.5 145.2 —2455766 2.094 0.03 — — 2.077 0.03 145.5 — 1442455767 2.172 0.03 — — — — 143.3 — —2455768 2.125 0.02 — — — — 142.8 — —2455769 2.187 0.03 2.181 0.03 2.091 0.03 143.7 144 145.62455770 2.161 0.03 2.162 0.02 2.099 0.02 143.4 143.2 144.82455771 2.175 0.03 2.148 0.03 2.143 0.03 143.9 144 144.82455775 2.203 0.03 2.178 0.03 2.106 0.03 143.8 143.6 1452455776 2.183 0.03 — — 2.086 0.02 142.7 — 143.42455777 2.137 0.02 2.151 0.02 2.148 0.02 142.5 142.3 142.72455778 2.114 0.03 2.132 0.02 2.107 0.02 142.4 143 142.62455779 2.118 0.03 2.086 0.02 2.052 0.02 142.9 142.4 144.52455780 2.085 0.02 2.086 0.02 2.026 0.02 142.7 142.1 143.72455781 2.068 0.03 2.087 0.03 2.051 0.02 143 142.8 144.42455782 2.069 0.03 2.072 0.02 1.997 0.03 142.4 141.3 143.62455783 2.062 0.03 2.015 0.03 2.056 0.03 141.3 141 141.32455784 2.047 0.03 2.077 0.03 2.025 0.02 141.5 141.5 141.22455785 2.058 0.03 2.053 0.03 2.018 0.02 142.6 141.8 140.72455788 2.054 0.02 2.015 0.02 1.988 0.02 141.8 141.1 142.82455789 2.026 0.03 2.003 0.02 1.968 0.02 143.1 142.8 142.72455790 2.012 0.03 2.011 0.02 1.986 0.03 142.1 141.2 143.12455791 2.063 0.03 2.012 0.02 1.998 0.02 141.6 140.6 142.62455792 2.047 0.03 1.992 0.02 1.988 0.03 141.3 140.9 141.72455793 2.047 0.02 2.025 0.03 2.006 0.02 141.2 140.6 142.32455794 2.05 0.03 1.948 0.03 2.012 0.03 141 140 142.22455795 2.057 0.03 2.054 0.03 1.948 0.04 140.8 139.8 141.82455796 2.033 0.03 1.973 0.03 1.984 0.03 141.3 141.3 142.42455798 2.015 0.03 1.962 0.03 1.935 0.03 141.4 140.4 141.82455799 2.003 0.04 1.94 0.03 1.935 0.03 142.6 141.9 143.42455801 1.999 0.03 1.939 0.03 1.453 0.03 141.7 141.2 —2455802 1.999 0.02 1.943 0.02 1.951 0.02 142 141.7 —2455803 1.976 0.03 1.96 0.02 1.944 0.02 143.1 142.9 143.82455821 — — 1.902 0.03 — — — 143.9 —2455822 1.974 0.03 1.862 0.03 1.91 0.03 143.8 144.2 145.32455823 1.947 0.03 1.891 0.03 1.924 0.03 145.4 145.5 145.52455824 1.946 0.03 1.878 0.03 1.91 0.03 145.3 145 1462455825 1.927 0.03 1.874 0.03 1.895 0.03 145.5 145.3 146.2




2455851 2.07 0.04 2.011 0.03 2.049 0.03 — — —2455853 2.043 0.04 2.019 0.03 2.001 0.03 — — —2455854 2.037 0.03 2.056 0.03 2.025 0.03 145.56144.36 143.662455856 2.036 0.04 2.03 0.04 2.037 0.03 142.41143.21 142.812455857 2.02 0.03 2.063 0.03 1.943 0.03 142.72142.22 152.922455858 2.034 0.02 2.056 0.02 2.041 0.02 143.02142.72 142.422455860 2.071 0.04 2.14 0.03 2.073 0.03 141.99142.09 141.892455861 2.157 0.04 2.189 0.04 2.064 0.04 142.05143.25 142.252455862 2.062 0.03 2.068 0.03 2.019 0.03 142.64142.64 142.442455863 2.065 0.03 — — — — 144.32— —2455865 2.008 0.03 1.964 0.02 1.977 0.03 143.31142.81 142.612455866 1.992 0.02 2.018 0.02 2.02 0.02 143.21143.01 143.012455867 2.01 0.03 1.975 0.02 — — 142.1 141.9 —2455876 2.057 0.03 2.091 0.03 2.061 0.02 — — —2455878 2.058 0.04 — — — — — — —2455881 2.029 0.04 1.983 0.03 2.011 0.03 142.8 141.8 144.22455882 2.032 0.03 1.988 0.02 2.032 0.02 143.2 142.3 144.52455894 2.005 0.03 2.022 0.02 1.999 0.02 138.1 138.3 138.72455895 2.057 0.03 2.005 0.02 2.03 0.03 143.5 143.2 144.82455897 2.082 0.03 2.067 0.02 1.989 0.02 143.5 142.6 145.62455898 2.128 0.03 2.069 0.02 2 0.03 143.7 143.1 145.62455899 2.067 0.03 2.078 0.03 2.039 0.03 143.3 142.7 145.32455902 2.091 0.03 2.044 0.02 2.049 0.03 143.2 142.6 144.62455903 2.073 0.04 2.064 0.03 2.037 0.03 148.2 142.7 144.92455904 2.067 0.03 2.057 0.02 2.018 0.03 144.1 142.7 144.72455905 2.078 0.03 2.066 0.02 2.065 0.02 142.8 143.3 145.62455906 2.123 0.03 2.06 0.03 — — 143.7 143 —2455907 2.105 0.03 2.07 0.04 2.048 0.03 143.6 142.3 144.82455908 2.098 0.03 — — 2.08 0.04 144.4 — 146.82455909 2.106 0.03 2.104 0.03 2.048 0.03 143.5 143.7 146.12455913 2.101 0.03 2.048 0.02 2.03 0.02 144.3 144 145.72455917 2.082 0.02 2.068 0.02 2.068 0.02 144.4 144.1 1462455918 2.08 0.03 2.089 0.02 2.044 0.02 142.8 142.3 144.12455936 2.004 0.03 1.944 0.02 1.919 0.02 145.1 144.6 146.82455938 2.04 0.06 2 0.03 — — 143.7 143.4 —2455939 1.972 0.02 2.014 0.02 — — 145.4 146.2 —2455940 1.951 0.05 1.969 0.03 — — — — —2455941 2.011 0.02 — — — — 145.1 — —2455944 2.028 0.03 — — — — — — —



Figu

re1

.eA

ure

clip

se:B

VR

per

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age

ofp

olar

izat

ion.

Va

rec

ircle

s,B

are

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ngle

s,R

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Figure3.eAureclipse:normalizedStokesparametersasafunctionoftime.

Figure 2. eAur eclipse:V percentage of polarization (p) andV positionangle(q).


Figure6.Overlayof1,utrendlinesforselectedepochs.

Figure5.eAureclipse:q,udiagramsforselectedepochs.

Figure4.eAureclipse:Stokesuasafunctionofqforallobservations.

Pearson and Stencel, JAAVSO Volume 40, 2012802

Modeling the Disk in the ε Aurigae System: a Brief Review With Proposed Numerical Solutions

Richard L. Pearson, IIIRobert E. StencelUniversity of Denver, Department of Physics and Astronomy, 2112 E. Wesley Avenue, Denver, CO 80208; address email correspondence to [email protected]

Received April 19, 2012; revised July 19, 2012; accepted August 7, 2012

Abstract Parameters associated with the opaque disk in e Aurigae areexplored in thecontextofcircumstellarandproto-planetarydisk theory.Theobservedblackbodytemperaturesofthedisk,at550and1150K,areprimarilydiscussed. Brief reviews of previous work are included that describe andattempttoexplainthistemperaturegradient.HeatingfromonlythecentralBstarprovidesabasaltemperatureofabout250K.Anaccretionrate(fromthedisktotheBstar)of10–7M

Ä/yralsoprovidesasimilarbasaltemperature;a

rateof1.5×10–5MÄ

/yrproducestemperaturesgreaterthan3000Kinthediskplane.ToincludetheFstarcontribution,MonteCarloradiativetransfertoolscanbeusedtoexaminenumerousseparationdistancesbetweenthetwostellarcomponents,withthegoalofmatchingtheobservedandmodeledtemperatures.AnestimationofthedistancetoeAurigaecanthenbeextracted.Theproposedmethodisdescribedhere.

1. Introduction

eAurigaeisasingle-linespectroscopicbinarythatfeaturesanopaquediskaroundacompanionthatcauseslengthyeclipsesevery27years(forareadinglist,seeCarrollet al.1991;Lissaueret al.1996;Stencelet al.2011).Figure1illustrates the configuration. Interferometric imagingproves the existenceofa disk andprovides somepreliminarydimensions for it (Kloppenborget al.2010), based on a highly uncertain Hipparcos distance of 625pc (Perrymanet al. 1997). The eclipse of 2010 provided a wealth of new data, from far-ultraviolettofar-infraredandsub-mmwavelengths(Hoardet al.2010;Stencelet al.2011;Hoardet al.2012).Forthiswork,wearespecificallyinterestedintheobservedsurfacetemperaturesofthediskasstatedinHoardet al.(2012)andprovidedhereinTable1. ThereisanunresolvedconcerninregardstopinpointingtheevolutionarystateofeAur.Twopartsofthisconcerndealwiththestellarmassesandthedistancetothesystem.First,themassesareunknown,butthebrightprimarystarresemblesanF0supergiantthatmaycontainasmuchas15–25M

Ä,oraslittle

as3–4MÄ

(ifitisanoverluminouspost-AGBstar,asinGuinanandDewarf

Pearson and Stencel, JAAVSO Volume 40, 2012 803

2002).Littletonoopticalspectrumexistsforthedisk-shroudedcompanionandthusitcannotbeclassifieddirectly.Spectroscopicinformationprovidesamassfunction value of 2.53 (Stefanik et al. 2010) and admits distance-dependentmassratiosof0.5–1.1.Eclipsedataandultravioletfluxessuggestthehiddencompanion could be a ≈ 6 M

ÄB5Vstar(Hoardet al.2010),with thebright

staranapproximately3MÄ

hyper-luminouspost-AGBstarinarapidstateofevolution(LambertandSawyer1986;Takeuti1986a;Saitoet al.1987;ShefferandLambert1999). Second, the actual distance to eAur is not well defined. The system isat the limitofavalidHipparcosparallacticdistance.Therealsoseemstobeintrinsic variability in the F star, which provides a varying star photocenterfor the parallactic measurements (Kloppenborg et al. 2011). Of course, anaccuratedistancemeasurementrefinestheconstraintsonthesystem’sphysicalparameters (forexample, stellarmasses, star-to-disk separations, andsoon).Someof the typicalparameters,using thehigh-errorHipparcosdistance,arelistedinTable1. Previous analytical and numerical modeling techniques have focused onresolvingthequestionablestateofeAur,byunderstandingthedisktoconstraincertainparametersoftheentiresystem.Theseincludediskthicknesslimitations(Lissauer et al. 1996), disk temperature studies (Takeuti 1986b; Hoardet al. 2010; Takeuti 2011), and spectral energy distribution (SED) matching(MuthumariappanandParthasarathy2012),forexample.ManyofthesemodelsusedtheHipparcosdistancetodefineparametersand/orusedonlyspecificpartsofthesysteminthemodeling(thatis,consideringonlythediskandBstar). In order to support the plethora of observations, modeling techniquesmustfurtherexplorethecompletenatureofthisdisk.Theobservedminimumand maximum disk temperatures (Tnoon = 1150 ± 50 K and Tmidnight = 550 ±50K)provideanavenueofinvestigation(Hoardet al.2012).Onecanlooktoreproducethesetemperaturesinanalyticalandnumericalstudies,byexaminingfoureAurdisk-heatingscenarios:

1.radiationfromthecentralstar(section2.1),

2.accretionalheatingfromthediskontothecentralstar(section2.2),

3.radiationfromthecentralandcompanionstars(section2.3),and

4.radiationfromstarsplusaccretionalheating(alsosection2.3).

Themotivationof thispaper is todescribe theneed tobuildacompletemodelof theeAur systembyusingnumericalmodeling techniquesand theobservedtemperatures.Fromthis,adistancecanbedetermined(asdescribedin section 2.3.2), thereby clarifying the evolutionary state. Sections 2.1 and2.2 establish possible disk basal temperatures and clarify that the observedtemperature gradient must be achieved by an external source. Section 2.3


describeshownumericalmodelingofallheatingcomponentscanaidinsystemconstraints.Thispaperpresentsabriefreviewofpreviousmodelingtechniquesandproposesadditionalnumericalsolutions.

2. Disk heating

A very useful tool in constraining certain parameters of the system arethe disk temperatures. By matching observationally constructed SEDs withblackbodytemperaturecurves,twotemperatureshavebeenestablished(Hoardet al.2012).HalfofthediskfacingoppositetheFstaristhe“midnight’’sideandfoundtobe550±50K.ThesidefacingtheFstar,“noon,”isfoundtohaveatemperatureof1150±50K.Decipheringhowandwhythediskexhibitstheobservedtemperaturegradientisimportantinunderstandingtheactualstateofthesystem. Weexploreheatingeffectsonthediskbythreedifferentsources:heatingfromthecentralstar,accretionalheating,andtheexteriorstellarsourceareallinvestigatedbelow.Briefreviewsofpriorworkareincludedaswell.

2.1.Centralstarinput We first consider a discussion concerning the effect of the central starradiationonthesurroundingdisk.Takeuti(1986b)analyticallysolvedforthetemperatureandscaleheightofthediskatspecifiedradii,basedonacentralBstarof4M

Ä,3R

Ä,andTeff=15000K.Blackbodyequilibriumtemperatures

of355and263Kwere foundatdisk radiiof2 and3AU, respectively.Nonumericalradiativetransferanalysiswasperformed.Thesignificanceofthesevaluesisdiscussedbelow. Morerecently,MuthumariappanandParthasarathy(2012,hereafterM&P)investigatedthecomposition,dustparticlesize,outerradiustemperature,andmass of the disk in eAur, using a two-dimensional, photon-tracking MonteCarlocode.TheirSEDresultswerebasedonenergyinputonlyfromaninternalB5V star. The system was assumed to be at the Hipparcos distance. Theycreatedmodelswithdustcompositionsofamorphouscarbon,ISMdistribution(60%silcatesand40%carbonates),andamorphoussilicates.Also,particlesizedistributions corresponding to minima--maxima ranges of 0.05–0.2mm and10–100mmwereapplied.AKuruczfluxmodelofa7700K,F0Iaepost-AGBstarwascombinedwiththeoutputSEDs.Then,comparisonsweremadewiththeobservationallydeterminedSED. TheirSEDfittingresultedina5×10–3M

Ädiskcomposedofcarbonates,

withgrain sizes10–100mm, andanouterdisk temperatureof252KatRout=3.8AU.Theothermodelsresult inouterdisk temperaturesof261–293K.These are, obviously, lower than the either of the observed Tmidnight or Tnoon.Takeuti (1986b)determinedaverycomparable temperature,asstatedabove.ThoughM&Pprovidenodiscussion concerning this, these findings indicate


thatmodelsbasedsolelyontheinteriorB5Vradiationprovideapossiblebasalheatinglevelwhichcanbecomparedagainstobservation.Furtherimplicationsofthisbasaltemperaturearediscussedinsection2.3.

2.2.Accretioninput Wenowexplorethedisktemperature,specificallyTmidnight,basedsolelyonaccretionalheatingfromthedisktothecentralstar.Armitage(2010,specificallysection3.3therein)describesasetofgeneraldiskequationsdescribingaccreting,Keplerian disk systems (for additional discussion, see Lin and Papaloizou1985).Turbulentmotionisusedastheprimarysourceofangularmomentumtransportwithinthedisk;itisportrayedasaturbulentviscosityinEquation1ofTable2.TheShakura-Sunyaevaparameter(ShakuraandSunyaev1973)isusedtodefinethedisk’sviscosity. The equations displayed in Table 2 have been adopted from Armitage(2010) and applied to the eAur disk.A previous iteration of this analyticalcalculationisfoundinTakeuti(1986b),whousesaformofEquations5,9,and10inTable2(alongwithacentralBstarasdescribedinthefirstparagraphofsection2.1) tocalculate temperaturesandscaleheightsatvariousdiskradii.Updatedtemperaturesandscaleheights,aswellasadditionalparameterssuchasdiskmassanddensity,arepresentedinTable3. If the central star mass (Mstar), accretion rate (M ), and disk radius (rdisk)are known, the equations inTable 2 depend only upon the mass absorptioncoefficient (k), the mean molecular weight (m), and the viscosity parameter(a).Therefore,bydefiningthesesixterms,afullsetofparametersdescribingthesystemcanbeoutput.Theopacitytemperaturedependence(k=k0T )andconstant(k=5×10–3cm2g–1)wereselectedfromLinandPapaloizou(1985)andPollacket al.(1985).Amolecularweightof1.5wasselected,whichislowenoughtoadmitthatthediskhasahighgas-to-dustratio,butshowsitisnotcompletelymadeofhydrogengas(m=1).Hartmannet al.(1998)determineda=0.01forTTauristardisksandthathasbeenadoptedhere.AccretionrateswereobtainedfromPequetteet al.(2011a),whoconcludesthathavingaM ≠ 0 was apossiblewaytoreproducecomparablemodelSEDstotheobserved.Pequetteet al.(2011a)statethatonlyahighaccretionrateprovidesanappropriateUV-to-IRratio.Fortheanalyticcalculationshere,twotypicalaccretiondiskratesof10–6and10–7M

Ä/yrwereusedalongwith1.5×10–5M

Ä/yrfromPequetteet al.

(2011a,2011b). Onceeachoftheinputvariableshavebeenspecified,allotherparametersbecomeuniquelydetermined.SelectedoutputvariablesaredisplayedinTable3.Ofnote,the10–6and10–7accretionratesproducediskmasses(2.9–9.25×10–3M

Ä)comparabletothemasspredictedbyM&P(5×10–3M

Ä);the1.5×10–5

accretionrateproducesadiskmassabouttentimesthatofM&P. Fordiskthickness-to-radiusratiocomparisons,anobservedvalueof0.08isgiveninTable1.Thisratiowascalculatedfromtheangularmeasurementsofthe


observedthicknessofthediskanditsradius.Lissaueret al.(1996)showsplotsofz/Rd,whichisequivalenttoN h/RoutwhereNisanintegernumberofscaleheightsinadistancez.TheanalyticalcalculationsinTable3showthatforthehighestaccretionrate,noneoftheN h/Routvaluesfallnear0.08.However,ratiosfromthe10–6and10–7accretionratesarecomparable.The10–6rateallowsforN=1orN=2,dependingonthecentralstarmass.The10–7rateseemstoprefereitherN=2orN=3,whichalsocoincideswiththeLissaueret al.(1996)models. Ifweassumeadustsublimationtemperatureof1500K,thentheTcvaluesforthehighestaccretionratearetoolarge,especiallyifparticlesaresupposedtobecoalescingintoprotoplanetaryobjects.However,asseeninFigure2,theonlyM tooutputaTdisknear theobservedmidnight temperature is the1.5×10–5 M

Ä/yr rate. If accretional heating was solely responsible for providing

the observed 550 K “midnight’’ temperature, then the predicted disk massfromthehighaccretionratemustbediscussed.Thediskmass fromTable3is41×10–3M

Ä,or43Jupitermasses,whichismuchlargerthananyprevious

prediction.WerethediskmassmorealongthelinesoftheM&P5×10–3MÄ

,thetimescaleforthediskwouldbeabout330years;sinceeclipselightcurvesofeAurhaveshownfairlyconsistantmagnitudedropsforalmost170years,a timescaleof only330years seemsveryunlikely.The existenceof amasstransferstream(fromtheFstartothedisk),however,couldextendthelifeofthedisk.Nevertheless,thepredictedmass,highTcvalues,andlarge h/RoutratiosdismissthelikelihoodofahighaccretionratepresentineAur.However,itdoesnotdismissthepresenceofaloweraccretionalrate. Accretionalheatingaloneisnotabletosupporttheobservedtemperaturedistribution(550–1150K)onthedisk.However,justasinsection2.1,thelowTdiskoutputfromtheloweraccretionratesmaybeabletoprovidealowerboundtemperatureforthediskintheeAursystem.Theeffectandrelationshipwiththeotherheatingmechanismsarediscussedattheendofsection2.3.

2.3.Companionstarinput ThetwoprevioussectionshaveillustratedtheimportanceofincludingtheF0star'sradiationinthemodelingtoexplainthedisk’sazimuthaltemperaturegradient.Thoughanexaminationofseparateheatingcomponentscanprovidespecificconstraints(thatis,abasaltemperature),thenextstepistoincludeallofthecomponentsofthesystem.Abriefreviewofpreviousworkrelatingtothedisktemperatureisdescribedtofurtherjustifytheneedfornewnumericalcomputations. The results of these new calculations will help provide anindependentmeasurementofeAur’sdistance.

2.3.1.Previousanalyticalstudies As previously mentioned, Takeuti (1986b) calculated disk temperaturesandscaleheightsfromtwoseparateradiationsources.Puttingthemtogether,Takeuti (1986b) postulates a possible disk configuration: a cool, thin disk


near “midnight” and subject only to the central star’s radiation; a crescent-shaped,opticallythickregiondominatedbytheFstar’sradiation;andasmall,optically thinregion,directlyopposite theFstarnear thedisk’sedge.Usingthisconfiguration,asteady-statediskassumption,andalimitingTmidnight=500K,anaccretionrateof2×10–11M

Ä/yrisfound.Thisaccretionratewouldnot

producetheobservedUVexcess(Hoardet al.2010).Takeuti(1986b)outlinesthat further ultraviolet and infrared observations are needed to resolve thequestionsconcerningthesystem. Twenty-five years later, Takeuti (2011) performed some analyticalcalculationsthatexploredtheouter-edgedisktemperaturevariationalongthediskplane,asheatedbyF0andB5Vstars.TheHipparcosdistanceof625pcwasusedtogeneratelinearseparationsinthesystem.Itisnotedthatsincethe“noon”temperatureistheaveragetemperatureoftheF0-facingsideofthedisk—similartotheaverage“midnight”temperatureoverthehalfofthediskfacingawayfromtheF0star—themaximumtemperatureat“noon”willbeslightlygreater than theaveragevalue,Tnoon (seeFigures1and2,aswellasTable2inTakeuti2011).Exploratorycalculationsconsistingofphysicallydescriptiveheatcapacitiesprovidedvariabletemperaturesaroundthedisk.However,theimplications(composition,particlesize,andsoon)oftheheatcapacitieschosenwerenotconsidered.Amaximumtemperatureof1200Kprovidedanupperlimitforthecalculations.Temperaturesatthe“midnight”positionwerefoundtobe250,500,and750K.Scaleheightswerealsocalculated toprovideanadditionalphysicalcorrelationwithprescribedmodels.Accretionalheatingwasignoredduring thiscalculation.TheworkofTakeuti (2011)provideshelpfulconstraintsthatcanbeusedinnumericalmodelcalculations.

2.3.2.Proposednumericalanalysis The processing power and speed of current computers allow numericalsimulationstoeffectivelydemonstratephysicalconfigurationsofastronomicalsystemsquickly.ForeAur,usinga three-dimensional (3D),photon-trackingMonteCarlocodewillpermitaninspectionofdisktemperaturesaccordingtoradiationfrombothstellarcomponents,aswellasaccretionalheating.However,the unknown (or rather, the known but highly uncertain) distance createssignificantproblemsinanalyzingtheradiationeffectsonthedisk.Therefore,adistance-—independentofanyobservationsotherthantemperature—canbedetermined, based on the reproduction of the known temperatures, Tnoon andTmidnight,onthedisk. Figure3displaystheprocessbywhichadistancecanbedetermined.First,adistance (dModel) is selected.Then,dModel isused toconvert allof thewell-determinedangularseparationsintolinearmeasurements.TheseparametersaretheninputintotheMonteCarlocode.Next,theMonteCarlocodeoutputsadusttemperaturefile(describedas“DiskTemperatures”inthefigure).ThepointsalongtheouteredgeofthediskfacingtheFstar,willbeaveraged— —Model

noonT< >


and compared with . If the modeled temperatures do not equal theobserved,anotherdistanceischosenandtheprocessiscontinued.However,ifthetemperaturesareequivalent,thenthesystemcanbedefinedbythechosendistanceandadditionalparametersarecalculated. Therewillbeaninherentrangeofdistancesthatarecapableofmatchingtheaveraged“noon”temperature,duetotheobservedtemperaturehavinganassociatederrorof±50K.However,thedistancerangesshouldbesufficientlysmalltoprovideconclusiveresults.Oncethedistancehasbeenestablished(withacertainamountofuncertainty),furthersystemsparameterscanbefinalized:themassfunction,themassratio,thetwostellarmasses,andthestellarradii.Knowingthese,theevolutionarystateofthesystemcanbeclarified. Anotherfeaturethatcanbeexploredisthedisk’scooling(andheating)rate.However,thenumericalmodelingonlyprovidesatemperaturesnapshotofthe“stable”system.Norotationofthediskisaccountedfor,andhence,thedustdistributed in thediskhasnoprior incidentheator radiation.Therefore, theoutputtemperaturesonlyaccountforthesnapshotofheatingthedustreceivesatthespecificmomentbeingexamined;atemperaturedistributionwillstillbepresentalongtheouterridgeofthedisk(forexample,Tnoon>Tmidnight),duetoshieldingeffectsoftheflareddiskandtheincreaseddistancefromtheFstarradiation.Atemperatureprofileofthediskcanbeconstructed(seeFigure4foranexample)andexamined. Comparisonsofthesnapshottemperatureprofilecanbecomparedagainstaprofileofarotatingdisk.Ifadiskrotationisassumed,thedustparticlesdirectlyinlinewiththecompanionFstar,at“noon,”willheatuptosometemperature,Tnoon.Asthedisk’sdustrotates,theamountofradiationfromtheFstardecreases;this allows thedust tobegin its coolingprocess.Thedustbegins toheatupagainwhenitagainreceivestheFstarradiation(seeTakeuti2011).Therateatwhichtheheatingandcoolingoccursishighlydependentonthecompositionof the dust. Once the maximum and minimum temperatures are acquired inthenumericalprocessoutlinedabove,temperature-timeprofilescanbecreatedfollowing Takeuti (2011). Various disk compositions will result in varioustemperature-time profiles. The shape and slope of profile can be comparedwiththesnapshottemperatureprofilestoassessthecompatibilityofthetwo. Thereareafewotherinputparametersthatwillneedtobefullyexplored.For instance, theaccretion rate.Since it isanunknown,numerous iterationswithvariousvaluesofM willneedtobecomparedateachchosendistance.Limitations have been placed on M previously, but since this is the firstcomplete3Dnumericalanalysisofthewholesystem,afullrangeofaccretionalrateswillbeexplored.Anotherrequiredinputisthedensity,composition,andparticlesizedistributionofthedisk.Theseaspectshavealargeimpactonhowthediskmaterialinteractswiththevariousheatingsourcesandhowitcools.Eachwillbeexploredwiththetechniquedescribedabove.Acompletesetofsolutionsareforthcoming.

ObservednoonT< >


Currently,two3DMonteCarlocodesareavailablethatpermittheinclusionofexternalradiationsources:Dullemond(2012)describesradmc-3d,whichusesacombinationoffortranandidlpackages;hyperionisoutlinedinRobitaille(2011),usingfortranandpythontocompleteitsanalysis.Bothhavetheabilitytomodelnon-symmetricsystems,whichillustratesthepowerof3Dmodeling.

2.3.3.Asimpleexampleofa3Dnumericalcalculation Todemonstrate theprimary results from this 3Dmethod, a hypotheticalexample is described here. Following the prescribed outline in Figure 3, anarbitrary distance of 830 pc was chosen. This places a user-defined F0 star(7750K,150R

Ä,3M

Ä)about30AUfromadisk-envelopedB5Vstar(15000K,

4RÄ

,6MÄ

)inradmc-3d.Asilicatediskwasmodeledwithinnerandouterradiiof1and4AU.Only10000photonpacketswerelaunchedduringtheradiativetransfercalculation,creatingaverystatisticallypoorsetofsolutions;however,thisissufficientforthisconjecturedcalculation. Theaveragedisk-planetemperatureatRout=4AUoftheF0-facingdiskwasabout1500K.ThistemperatureishigherthanthevaluespredictedbyTakeuti(2011)and ,butstillrelativelyreasonable.Theareaofthediskatthe“noon”positionmaxedatabout2500K,whichissignificantlyhigherthantheTakeuti(2011)estimationofabout1600K.Anaverage“midnight”temperatureofabout900Kwasfound,whichisalsolargerthanthe .Acompleteanalysis, as described previously, is not presently provided. A graphicalrepresentationisshowninFigure4. Itisnotedthatthisbriefexampleusesonlyasilicatediskandprovidesnoaccretionalheating.Afullanalysiswillexaminethediskcompositionandwillincludeanaccretionalrate.Still,thedisregardforaccretionalheatingmaybeaplausibleassumptionbasedontheB5Vtemperature:iftheoutwardradiationpressurefromtheB5Vstarislargeenough,itwouldseverelylimitthemassflowfromthedisktotheB5Vstar. A final note is made here concerning the and the coldesttemperatureof theradmc-3dmodel.Abasal temperatureofabout250Kwasfound in sections 2.1 and 2.2. The work by Takeuti (2011) place this basaltemperaturenearthe“dusk”positiononthedisk(refertoFigure1).Therefore,onecanexpect theobservedTmidnight tobelargerthanat“dusk.”However, inthishypotheticalcalculation,anaveragebasaltemperaturewasfoundatabout500K.Adjustments to the distance, separation, composition, transmissivity,and/orotherinputparametersofthesystemcanbemadetofindreasonableandcomparable“dusk,”“noon,”and“midnight”temperatures. Thoughjustahypotheticalnumericalcalculation,thisexampleshowsthatthetemperatureresultswillbeabletoprovidedistanceanddiskcompositionpredictions.Itoutlinestheusefulnessofincorporatingbothstarsinanumericalsimulationandtheneedtoexploretheeffectsofaccretionalheating.

ObservednoonT< >

ObservedmidnightT< >



3. Conclusion

WehavedemonstratedtheneedforfutureanalyticalandnumericalmodelsofeAur to include the radiationeffectsof thecompanionstar.Additionally,wehaveproposedawaytodeterminethedistancetothesystembyusingtheobservedtemperatures.Abriefreviewofpreviousdisktemperaturemodelingwas provided to give context to the proposed numerical solutions. Furtherclarification regarding theevolutionary stateof theeAur systemmay resultfromthedescribedanalysis.

4. Acknowledgements

Weappreciate the expert adviceprovidedbyBrianKloppenborgwhileconstructing this article.This work was supported in part by the bequestofWilliamHerschelWomble in support of astronomyat theUniversity ofDenver,forwhichwearegrateful.

References

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Carroll, S. M., Guinan, E. F., McCook, G. P., and Donahue, R. A. 1991,Astrophys. J.,367,278.

Dullemond,C.P.2012,RADMC-3D:Anewmulti-purposeradiativetransfertool(http://www.ita.uni-heidelberg.de/dullemond/software/radmc-3d/).

Guinan, E. F., and Dewarf, L. E. 2002, in Exotic Stars as Challenges to Evolution,ed.C.A.ToutandW.vanHamme,ASPConf.Ser.,279,Astron.Soc.Pacific,SanFrancisco,121.

Hartmann,L.,Calvet,N.,Gullbring,E.,andD’Alessio,P.1998,Astrophys. J.,495,385.

Hinkle,K.H.,andSimon,T.1987,Astrophys. J.,315,296.Hoard,D.W.,Howell,S.B.,andStencel,R.E.2010,Astrophys. J.,714,549.Hoard,D.W.,Ladjal,D.,Stencel,R.E.,andHowell,S.B.2012,Astrophys. J.,

Lett. Ed.,748,L28.Kloppenborg,B.K.,Hemenway,P., Jensen,E.,Osborn,W., andStencel,R.

2011,Bull. Amer. Astron. Soc.,43,230.05.Kloppenborg,B.,et al.2010,Nature,464,870.Lambert,D.L.,andSawyer,S.R.1986,Publ. Astron. Soc. Pacific,98,389.Lin,D.N.C.,andPapaloizou,J.1985,inProtostars and Planets II,ed.D.C.

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423,2075.Pequette,N.,Stencel,R.,andWhitney,B.2011a,Bull. Amer. Astron. Soc.,43,

225.05.


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Table1.AdoptedeAursystemparametersusingd=625pc. Parameter Value Comments*

Primary Star

Temperature,TF 7750K BasedonF0typeandSED Radius,RF 150R

Ä interferometricdiameter(1)

Mass,MF 3MÄ

diskradialvelocity(2)

Secondary Star

Temperature,TB 15000K DeterminedasB5V,from far-UVandHe10830(3) Radius,RB 4R

Ä BasedonB5V

Mass,MB 6MÄ

BasedonB5V

Disk

InnerRadius,Rin 1AU Assumed OuterRadius,Rout 3.8AU (4) Observed Inclination 89˚ (4) and (5) DiskTemperature 550–1150K Midnighttonoon,relative toFstarphase(6) ObservedThickness/Rout 0.08 (4) TotalnumberdensityatRout 1.6×1012cm–3 obtainedfromCOlines(7)*References: (1) Stencel et al. (2008); (2) Lambert and Sawyer (1986); (3) Stencel et al. (2011); (4) Kloppenborg et al. (2010); (5) Hoard et al. (2010); (6) Hoard et al. (2012); (7) Hinkle and Simon (1987).


Table2.Analyticdiskequations,adoptedfromArmitage(2010). Variable Equation Units Equ. No.

viscosity n=acsh cm2s–1 1

soundspeed c2s= cms–1 2

angularvelocity W2=G Mstar/r3disk s–1 3

density r= g cm–3 4

scaleheight h= cm 5

mid-planetemperature Tc4= K 6

opticaldepth t= 7

opacity k=k0Tc cm2g–1 8

massflow nS= gs–1 9

effectivedisktemperature T4disk= K 10

surfacedensity S4= g cm–2 11

kBTcmmp

1√2p

Sh

cs

W

34 tT 4

disk

12 Sk

M3p

9n8s SW2 1–√ Rstar

rdisk( )

64s27k

01–√ Rstar

rdisk( )W (mmp

akB)3M3p( )2

Table3.Analyticalsolutionsusingsilicatedust.

k = k0Tc, k0 = 5 × 10–3 cm2 g–1 K–1, a = 0.01, m = 1.5

MB=6MÄ

MB=8MÄ

M [MÄ

/yr] 1.5 × 10–5 10–6 10–7 1.5 × 10–5 10–6 10–7

S[102g cm–2] 67 17 5.5 70 18 57 Mdisk[10–3M

Ä] 34 8.9 3.5 41 9.2 2.9

Tdisk[K] 520 270 150 560 290 160 Tc[K] 3600 920 290 4000 1000 330 h[1012cm] 6.7 3.4 1.9 6.2 3.1 1.8 h[AU] 0.45 0.23 0.13 0.41 0.21 0.12 3h/Rout 0.36 0.18 0.10 0.32 0.17 0.093 2h/Rout 0.24 0.12 0.07 0.22 0.11 0.062 h/Rout 0.12 0.06 0.03 0.11 0.055 0.033 n[1013cm–3] 16 8.1 4.5 18 9.2 5.2


Figure 1. Side and top-view sketches (not-to-scale) of the e Aur system.ParameterscoincidewithvaluesgiveninTable1.

Figure2.Achartdisplayingdisktemperatures,Tdisk,attheouterradiusoftheeAurdisk.Theseareresultsofananalyticalstudyofthesystem.Twodifferentcentralstarmasseswereusedinthecalculations:MB=6M

ÄandMB=8M

Ä.

Thedottedlinerepresentstheknownobservedtemperature, .Notethattheonlymodeltoreachandexceedthisvaluepredictsaveryhighaccretingrateof1.5×10–5M

Ä/yr,whichisnotphysicalfortheeAursystem.Thoughthe

otheraccretionratesdonotprovideamatchingtemperature,theydocomparetotheminimumdisktemperaturesstatedbyMuthumariappanandParthasarathy(2012)andTakeuti(2011).



Figure 4.A plot describing the temperature distribution from a hypotheticalnumerical modeling reconstruction of e Aur, from radmc-3d. The average“noon’’ and “midnight’’ temperatures were calculated by averaging thetemperatureslocatedattheouteredgeofthedisk,intheassociatedareasofthedisk.Theminimumandmaximumtemperaturesassociatedwiththenumericalmodelingareshown,aswellasahypotheticaltemperaturegradientrepresentedbythesolidblackline.Again, thelineisnotafit toactualdata: it issimplyagraphical representationofapossible temperaturedistributionon thedisk,outlinedbytheminimumandmaximumtemperatures.Noaccretionalheatingordiskrotationwasused.

Figure 3. A schematic showing the process of solving for the distance toeAur.Notethatthereareafewotherinputparametersbesidesjustthebinaryseparation.These includedustcomposition,dustmolecularweight,anddustdensity distributions. See text for further information regarding analyticalstudiesandnumericalmodeling,specificallywithradmc-3d.


A Demonstration of Accurate Wide-field V-band Photometry Using a Consumer-grade DSLR Camera

Brian K. KloppenborgDepartment of Physics and Astronomy, University of Denver, 2112 East Wesley Avenue, Denver, CO 80208; [email protected]

Roger Pieri37 C rue Charles Dumont, 21000, Dijon, France; [email protected]

Heinz-Bernd EggensteinVogelbeerweg 34, 31515 Wunstorf, Germany; [email protected]

Grigoris MaraveliasPhysics Department, University of Crete, GR-71003 Heraklion, Crete, Greece; [email protected]

Tom Pearson1525 Beachview Drive, Virginia Beach, VA 23464; [email protected]

Received May 8, 2012; revised July 3, 2012; accepted July 3, 2012

Abstract TheauthorsexaminedthesuitabilityofusingaDigitalSingleLensReflex(DSLR)cameraforstellarphotometryand, inparticular, investigatedwidefieldexposuresmadewithminimalequipmentforanalysisofbrightvariablestars.Amagnitude-limitedsampleofstarswasevaluatedexhibitingawiderangeof(B–V)colorstakenfromfourfieldsbetweenCygnusandDraco.ExperimentscomparinggreenchannelDSLRphotometrywithVTphotometryoftheTycho2catalogue showed very good agreement. Encouraged by the results of thesecomparisons,amethodforperformingcolor-basedtransformationstothemorewidelyusedJohnsonVfilterbandwasdevelopedandtested.ThismethodissimilartothatrecommendedforTycho2VTdata.TheexperimentalevaluationoftheproposedmethodledtorecommendationsconcerningthefeasibilityofhighprecisionDSLRphotometryforcertaintypesofvariablestarprojects.Mostimportantly,wehavedemonstratedthatDSLRcamerascanbeusedasaccurate,wide field photometers with only a minimal investment of funds and time.

1. Introduction DigitalSingleLensReflex(DSLR)camerashavebeensuccessfullyusedbyastrophotographerssincetheadventoftheseimagingdevices.Shortlyaftertheirintroduction,severalstudiesexaminedthesuitabilityofDSLRsforphotometry.Becausetheyarenotdesignedforphotometry,thesecameraspresentauniquesetofchallenges.Forinstance,DSLRsensorsaremanufacturedwithaBayerarrayofred,green,andbluefiltersplacedoverindividualsensorpixels.Unfortunately,


thecenterwavelengthsofthesefiltersdonotmatchthewavelengthsofstandardJohnson filters. Furthermore, features that improve image quality like built-insoftwarenoisereductionalsodistortthetruephotometricsignatureofstarsof interest. Fortunately, camera manufacturers have given consumers accessto the RAW pixel data, which is often free of any on-camera processing ornoisereduction. ExamplesofphotometrytestingofDSLRsincludeworkbyHoot(2007).HetestedaCanonEOS350DasastellarphotometerbyimagingaseriesofLandoltfieldstars.UsingtheLandoltV,B,andRfilters,hecomputedoffsetsandcolorandextinctiontransformations.Hootfoundsignificant(~0.13mag.)uncertaintiesinthecolorcorrectioncoefficientsthatwerefarinexcessoftheinstrumentalRMS(~0.003mag.)values.Fromthisheconcludedtheremustbesomeoutlyingsystematiceffectcausingthelowqualityoffit.Furthermorehefoundthat“nosingleexposuresettakenwiththisDSLRfamilyofcameracanaccuratelyspanmorethan2.5magnitudes.’’Outsideofthisnarrowwindow,theerrorsincreaserapidly,thereforedecreasingtheutilityofusingDSLRcamerasforfieldswithwidemagnituderanges. SubsequenttopublicationofHoot’sarticle,DSLRcameraswereputtothetestonvariousastronomicaltargets.Littlefield(2010)andGuyonandMartinache(2011)haveshownDSLRcamerasarecapableof10milli-magnitudeorbetterphotometry that is suitable for tracking transiting exoplanets. Fiacconi andTinelli (2009)haveshownDSLRcamerascan trackpulsatingvariablestars,likeXXCyg.Allthreeofthesestudiesmadeuseofdifferentialphotometrythatdoesnotrequireaprecisetransformationtoastandardphotometricsystem.ArecentstudybyPataet al.(2010)showsthatsuchtransformationsareindeedpossible,providedthatthespectralpropertiesoftheobservedstarsareknown. AspartoftheAmericanAssociationofVariableStarObservers’(AAVSO)CitizenSkyProject,severalparticipantselectedtouseDSLRcamerastotrackthe2009–2011eclipseofeAurigae(Stencel2008;GuinanandDewarf2002).The success of this method (Kloppenborg and Pearson 2011; Kloppenborget al.2011)inspiredourworkwhichconfirmsthatDSLRcamerascanindeedbeusedas accurate, photometrically calibrated,wide-fieldphotometersoverawiderangeofcolorsandnearly fivemagnitudesofbrightnesswithaverymodestinvestmentoftimeandequipment.Whattheylackinflexibility,DSLRcamerasmakeupforinpriceandportability.

2. Procedure

2.1.Instrumentationandexperimentalsetup ForourworkweusedastandardCanon450D,withoutmodifications tothefilters,andtwoNikkor lensesadaptedto theCanonbody.The450Dhasa22.2×14.8mm,12-megapixelCMOSsensorand isequippedwitha14-bitanalog-to-digitalconverter.Weverifiedthecamera’slinearresponseovermost


ofitsdynamicrangebycomparingsensorresponsetoaseriesofilluminatedtargets.Targetbrightnesslevelsweremeasuredusingadedicatedphotometer.AtISO100,the450Dappearstobelinear(within±0.5%)upto14,300ADU,wherethecamerasharplydepartsfromthelineartrend(fullwellsaturation).TheADCclippingleveloccurredat~15,800ADU,ratherthantheexpected16,384fora14-bitcamera.ThecalibrationfactoratISO100hasbeenmeasuredto2.27e-/ADU.Thereforethe1electronto1ADUcalibrationsettingresidessomewherebetweenISO200andISO400.Abovethissetting,thedynamicrangeofthecameraisreduced.WeusedstandardNikkor200-mmand85-mmlenseswhosefieldsofvieware6.36×4.24degreesand15×10degrees,respectively. Wemeasured the spectral responseofourcamera’sRed (R),Green (G),andBlue(B)Bayerarrayfilters.Figure1aisaplotoftheCanon450DGfiltercomparedtotheJohnson’sVfilterdefinition(MaízApellániz2006).Wefoundthe G channel is shifted blueward by 12nm relative to Johnson’sV-filter.Atransformationequationis,therefore,requiredtoadaptDSLRmeasurementstothisphotometricstandard.Likewise,wefounda2-nmblueshiftbetweenTychoVTandDSLRG(seeFigure1b),butthisshiftisnearlynegligible.Thisresultisquiteinterestingasitshowsthereshouldbelittletonocorrectionbetweenthe450DGchannelandTychoVT.Thesepropertieswillbeverifiedanddiscussedingreaterdetailbelow. Ofnotearesomeusefulfeaturesofthiscameratoaphotometrist.Thecamerahas a 10× magnified live-view display that is very useful when defocusing.Unfortunately,wefounditisoftennotpossibletoframethefieldofinterestbyusingtheliveviewat1×zoom.Insteadweusedtheopticalviewfinderwitharightangleadapteradded.Additionally,weusedareddotfinderattimes.Tobestsimulatethefacilitiesavailabletootherobservers,wemountedourcameraon a small, undriven, equatorial mount to accelerate framing of the chosenfields.Asimpletripodcanalsobeused.

2.2.Choiceofstarfields Our star fields were selected to optimize testing the limits of DSLRphotometryandtherelatedpost-processingsteps.InchoosingourtestfieldweintentionallyexcludedregionsintheplaneoftheMilkyWaytoavoidblendingtargetstarswithpotentiallyunseen,butdetectable,backgroundstars.OurfourfieldsarefoundbetweentheconstellationsCygnusandDracoboundedbyR.A.19h48mto18h05m and Dec. +48˚ 07' to +54˚ 28'. These fields total 15.85 × 6.36 degreesor101squaredegreesandhave~283starsbetweenV=3.7and8.75with(BT–VT)valuesof–0.2to2(seeFigures2aand2b).Ofthese,VizierandVOPlotreport76starsareatriskofblendingwithinthephotometricapertureand27starsaresuspectedvariables(seeTable1).MoststarsinthefieldareAFGandK spectral types,with a fewB- andM-type stars (seeFigure2c).BecauseofthelimitednumberofM-stars,wewerenotabletochecktheknowntransformationissuesinvolvingtheseobjects(Perrymanet al.1997).Wealso


obtainedimagesfromasecond,largerregionusingthe85-mmlens.ThisareaextendedbetweenR.A.19h48mto17h10m and Dec. +44˚ to +59˚ in three fields. ThesedatahavesignificantfielddistortionsneartheedgeoftheFOVthatmustbedealtwithdelicately.Wewilldiscussthesedataandourmethodofreductioninafuturepublication.FortheremainderofourdiscussionweshallrefertoourobservedfieldsasCD3S,CD4S,CD5S,andCD6SassummarizedinTable2.

2.3.Dataacquisition OurobservationsbeganonJuly14,2011,andendedonSeptember28,2011.All imaging was done from the same location: +47˚ 19' N, +05˚ 01' E at 250 maltitude.Alldataweretakeningroupsof10to15images(hereaftera“series’’)withtheCanon450DandNikkor200-mmlensatf /4,ISO100with12.3-secondexposure times, except a few of the CD3S field which uses only 8-secondexposures.Thenumberofimagesperserieswerechosentoreducethenoisefromatmosphericscintillationtoafewmilli-magnitudes.Allimagesweredefocusedslightly(seeFigure3)sothatthestellarimagecoversroughlya10-to15-pixeldiameter(plustrailingduringtheexposure).Mostoftheimageswereacquiredwithin15to30degreesofthezenithwheredifferentialairmassisnegligible.FourseriesforCD5SandCD6Swere takenat40 to45degreesofzenithatabout1.5airmasses.Fromtheseimages,wefoundthatthebrighteststarsinoursample(V~3.7)haveaSNR>>1,000andstarsat7thmagnitudehaveSNR~200. Because we used a fixed focal length lens, it was possible to use a flatimagerecreatedeveryfewmonths.Theflatisobtainedbyimagingadiffuselyilluminated,non-glossy,fine-grainedwhitesurface(forexample, thebackofhighqualityphotopaper).A1%cross-surfaceuniformityofourflatfieldingsourcehasbeenverifiedusingadedicatedphotometer.

3. Data reduction

Toreduceourdataweemployedtwomainstages.Thefirststageextractsthe instrumentalmagnitudesandstatistical informationfromthe rawcameradata,correctingforflatfielding,whilethesecondstagecalibratesthedatatoanabsolutephotometricsystem.

3.1.Stage1 AnautomatedreductionpipelinehasbeenwritteninAPLlanguagerunningunderaDylogAPLenvironment.Thispipelinedoesthefollowing:

1. Extracts therawBayerdata inRGGBformat fromthecamera’sCR2files usingdcraw (fromDaveCoffin, http://www.cybercom.net/~dcoffin/dcraw/).

2. TheimageissplitintothreeplanesformedbytheR,(G+G)/2,andBpixelsfromtheBayercell.Thisyieldsa2145×1428RGBimage.


3. TheCanon’ssystematicoffsetof1024ADU(possiblyincludedindark)is first subtracted from the raw.The resultant image is then flat fielded.Eventhoughtheimagelooksveryuniform,wehavenoticedasmallnon-uniformity in the the outer perimeter of our images, and therefore weexclude a 50-pixel-wide border from photometric analysis. We do notapplyadarkimageaswehavefoundtheseshortexposuresatISO100haveminimaldarkcurrentnoise.Anyresidualcross-imagegradientswilleasilybedetectedinstage2,manifestingintheextinctioncoefficient.

4. Nextwecreateatemporaryluminance(R+G+B)imagetodetectstars.Theimageissampledatseveralpoints todeterminethebackgroundandisfitusingapolynomial.Thisfunctionisthensubtractedfromtheimage,removinganyremainingsystematicbackground.Theresultingluminanceis again measured and pixels residing above 3-sigma (noise) above thedarklevelareselectedascandidateobjects.Theareaaroundthebrightestpixelsareanalyzedtodetermineiftheyarepartofastar.Ifconfirmed,thefootprintof thestar ismeasuredand itsgeometriccentroidcalculated toensurepropercenteringduringaperturephotometry.

5. Because of diurnal motion, our star images are trailed.Therefore weperformaperturephotometryusingrectanglesratherthanannuli.Ourinnerapertureis21×13pixelsandtheouteris51×51pixels.Thebackgroundlevelforeachstar,determinedfromtheouteraperture,issubtractedfromtheforegroundapertureandtheRGBintensitiesofthestarareextracted.

6. Next, starsare identifiedusing theTycho 2 referencecataloguebaseduponimagecoordinatesanda“tentative”instrumentalmagnituderelativetotheensembleofstarsintheimageiscomputed.

7. LastlythestarID,RGBintensities(inelectrons),R.A.,Dec.,andimageposition(X,Y)arewrittentoafilealongwithaggregatestatisticslikeseriesmeanaltitude,means,standarddeviations,andsignal-to-noiseratio(SNR).

ForouranalysisweselectedonlystarswhoseSNRoveraseriesisgreaterthan40.Belowthislimit,astar’sSNRisnolongerabovethe3-sigmacriterionfortheautomatedextractionpipeline.

3.1.1.Stellarblending Onedownsideofwide-fieldDSLRphotometryisthatrelativelylowangularresolutionofthecameracanblendtwonearbystarstogether.Uponexaminingour instrumental output table from the steps above, we found a significantnumberofoutliersfromthecalibrationtrendweexpected.Someofthesestarswereundoubtedlyvariables,butinmostcasestheywereaffectedbyblendingwithfaintbackgroundstarsthatfellwithintherectangularaperture. Tosolvethisissuewewroteasmallpieceofsoftwarethatusesdatafrom


the Tycho 2 catalog down to VT=13.All stars that fall within the apertureare selected and their approximate flux is computed. If the background starcontributionexceeds0.012magnitude,weflagitinourdatatables.IfthePointSpreadFunction(PSF)responseof thecamerawerebettercharacterized,wespeculateitwouldbepossibletoremovethebackgroundstarcontribution,butthiswasbeyondthescopeofthispaper.Anystarsthatwereaffectedbyblendingwerenotusedinouranalysis.

3.1.2.Variablestars Inasimilarmannertoblendedstars,wehavealsoflaggedvariablestars.Wehavecollectedaggregatestatisticsonvariability,spectraltypes,andluminosityfrom the Tycho 2 (Høg et al. 2000a, 2000b), Hipparcos Input (Turon et al.1993),Hipparcos Main(Perrymanet al.1997),andtheTycho 2 Spectral Types(Wright2003)catalogues.Ofourtargets,twenty-fourwereflaggedasvariablestars from the input catalogs;however, sixof these stars showedno signofvariationwithinourmeasuredaccuracy.

3.1.3.Finalstarselectionandoutputquality These observations have provided 201 stars from the four fields fromVTmagnitude3.8to8.8.Ofthese,67havebeendeselected(18variables,52blended),yieldingatotalof134starsforfurtherprocessing.AggregatestatisticsofthesestarsareshowninFigures2a,2b,and2c.

3.2.Stage2 ThesecondstageofdatareductionmirrorsthetechniquesemployedintheCitizenSkyIntermediateReductionSpreadsheet.ThismethodtransformstheDSLRinstrumentalGmagnitude(denotedusingnhereafter)intothestandardphotometricsystem(denotedusingcapitallettersVandB)usingthestandardtransformationcoefficientmethod(comparetoHendenandKaitchuck(1982)andreferencestherein).Thismethodessentiallyfitstheobservedinstrumentalmagnitudes to a 3D surface todetermine the transformation coefficient (e),extinction coefficient (k' ), and zero-point offset (z

n).The remainder of this

section reviews this method by outlining the mathematics required to findtheseparameters.

3.2.1.Determiningeandzn

For differential photometry in which airmass may be neglected, thetransformation coefficient (e) and zero point offset (z

n) may be determined

usingthefollowingequation(HendenandKaitchuck1982):

(V – n)i=e(B–V)i+zn, (1)

whereBandV arethecatalogB-bandandV-bandmagnitudes,nistheobservedinstrumentalmagnitude,eisthetransformationcoefficient,andz

nisthezero-


point offset of the camera.The subscript i denotes the ith calibration star intheimage.BecauseofthewayinwhichCMOSsensorsaremanufactured,weassume,tofirstorder,thattheresponseofeachpixelinthecameraisnearlyidentical.Therefore, ifproperbackgroundand flat subtractionmethodshavebeenappliedeandz

nareconstantacrossthefield.Wemaytheneithersolve

thisequationgraphicallyorusealinearleast-squaresfit(seePaxson2010)inordertodetermineeandz

n.

Afterthecoefficientsaredetermined,theaboveequationmayberearrangedandtheV-bandmagnitudeforthejthtargetstarcomputedvia:

Vj = nj+e(B–V)j +zn, (2)

3.2.2.Airmasscorrections Theabovemethodofcalibratingisgoodforimagesofsmallangularextent(that is, those with < 3˚ FOVs) at zenith angles less than 34 degrees. Beyond thispoint,thedifferentialairmassacrossthefieldcancontributesignificantlytotheerror.FirstorderairmasscorrectionsmaybeappliedtoDSLRimagesusingthefollowingequation(HendenandKaitchuck1982):

(V – n)i=–k'nXi+e(B–V)i+z

n (3)

where thenewly introducedvariable,k'n, is theextinctioncoefficientandXi

is the airmass. This equation has the same functional form as a geometricplaneinthreedimensions:z=Ax+By+C.Ifweassumethattheinstrumentalmagnitude,ni,dependsonlyonthetermsontherightsideoftheaboveequation,thenwemaysolve theaboveexpressionfor thecoefficients (–k'

n,e,andz

n)

usingaminimumofthreecalibrationstarsinthefieldofview.However,ifonecalibrationstarisincorrectlyidentifiedortheairmassisincorrectlycomputed,thecoefficientswillbeskewedandtheresultingmagnitudesfortargetstarswillbe invalid.Thereforewealleviate thisproblembyusingmultiplecalibrationstarstocomputethecoefficients. Aleast-squaresfitofncalibrationstarstotheplanedefinedbytheequationz=Ax+By+Cisfoundbysolvingforthecoefficientmatrix,X,infollowingexpressions,usingtheinverseofA:

AX = B (4)

Sn

i=1x2i S

n

i=1xi yi Sn

i=1xi

Sn

i=1xi yi Sn

i=1y2i S

n

i=1yi

Sn

i=1xi Sn

i=1yi Sn

i=11

–k'u

e =

zu

Sn

i=1xi zi

Sn

i=1yi zi

Sn

i=1zi

(5)

⎡ ⎤⎪ ⎪⎪ ⎪⎪ ⎪⎪ ⎪⎣ ⎦

⎡ ⎤⎪ ⎪⎪ ⎪⎪ ⎪⎪ ⎪⎣ ⎦

⎡ ⎤⎪ ⎪⎪ ⎪⎪ ⎪⎪ ⎪⎣ ⎦

It isnotnecessary towriteacomputercode to solve theseequations,asmany spreadsheetprogramsandprogramming languages alreadyhavebuilt-


in routines forsuchapurpose.Forexample,excel/openoffice calchave the“linest’’ function which we have employed in the Intermediate ReductionSpreadsheetontheCitizenSkywebsite.Ifyouwishtowriteyourownreductioncode,Python’s“scipy.optimize.leastsq’’functioncanbeusedforthistask. After thecoefficientsaredetermined, themagnitudeof the jth star in thefieldofviewmaybedeterminedbyrearrangingEquation6:

Vj = nj+–k'nXj +e(B–V)j+z

n (6)

Note that these equations require that the color of the target stars mustbeknowna priori!ThisplacesaDSLRcameraatasignificantdisadvantagebecause even though the Blue and Red channels are measured, they do notcorrespond to any standard photometric filters. Furthermore, the spectralresponseoftheRedandBluepixelsoftenareasymmetricwithmodestredandblueleakscomparedtostandardfilters.ThisdisadvantagecanbemitigatedbyusingacatalogthatcloselyrespondstoDSLRG,therebyresultinginanear-zerovalueforeandmitigatingthecolorcontributiontofinalV-bandoutput.

3.3.Verification InadditiontotheAPL-basedpipelinedescribedabove,oneofus(H.B.E.)createdanalternativereductionmethodthatusesaip4win(BerryandBurnell2005)tostackimages,sourceextractor(BertinandArnouts1996)toautomaticallyfind and perform aperture photometry on stars, and scamp (Bertin 2006) toperformastrometricstarassociation.Theoutputisthenprocessedinthesamemannerasstep2describedaboveusingascriptwehavewritteninR(Matloff2011).This second pipeline produced results identical (within uncertainties)tothemethoddescribedabove.PleasecontactH.B.E.ifyouareinterestedinvirtualmachineimageofthefreelyredistributablecomponentsofthispipeline.

4. Results

Ourdatasetconsistsofnearly500imagestakeningroupsoften,12-secondexposures.These40seriesrepresentnearly80minutesofcombinedexposuretime.Fromtheinputcatalogofapproximately300starsbrighterthanV=8.8,wedetectedabout200starsinourfieldsthatare3-sabovebackgroundnoise.Fromthese,weselected134starsthatwerefreefromblendingandnotidentifiedasvariables(orsuspectedvariables)incatalogues.Overall,starswith3.5<V<7.5hadameanuncertainty<0.01magnitudeorbetter.Starsintherange7.5<V<8.0hadanaverageuncertaintyof~0.02magnitude.Beyondthismagnitude,photometricuncertaintiesrapidlygrew∝1/SNR.WeshowtypicalresultsforconstantandvariablestarsinFigure4.

4.1.Choiceofcalibrationcatalogue Followingourdiscussionattheendofsection3.2.2wehaveexploredthe


useofonehomogeneousphotometriccatalogandoneinhomogeneoussourceforstage2calibration.Inthenextfewparagraphswedescribethebenefitsofusingastandardizedsystemandcautionagainstusinginhomogeneouscatalogsforcalibration.

4.1.1.Tycho For our first calibration catalog we used the Tycho 2 Catalogue (Høget al. 2000a, 2000b). As discussed above, the difference in transmissionbetweenVTandDSLR-Gfilters isminimal. InFigure5aandFigure5bweadjustedDSLR-GtoVTusingonlyazeropointoffset,z

n.Theresiduals(that

is, transformed–catalog) appear normally distributed about zero and shownosystematictrendsasafunctionofcolor,confirmingthesuspicionthatthedifferenceintransmissionbetweentheVTandRGB-GfilterscanberegardedasminimalfortheCanon450D.

4.1.2.ASCC Unlike Tycho VT, the Johnson V measurements in the ASCC catalog(Kharchenko2001)shouldexhibitamodestcolor transformationcoefficient.Foralmostallofourtargetstars,ASCCcontainsVTmagnitudestransformedtoVJ . In Figure 6a we plot the instrumental magnitudeninst as a function oftheASCC2.5JohnsonV.Todemonstratethecolorcorrelation,thedifferencebetweeninstrumentalandcatalogmagnitudeisplottedasafunctionof(B–V)inFigure4b.NotethatunlikeouranalysisfortheVTphotometry,andunliketheanalysisinHoot(2007),wefindasignificantcorrelationbetweentheresidualsandcolor. NextweappliedthefullcolorcalibrationtothedatatoyieldFigures5cand5d.Asidefromasmallexcursionbetween0.4<(B–V)<0.5(whichcontainsonly stars with V > 8 with very poor SNR), we find the data are normallydistributed. Likewise, residuals as a function of magnitude appear normallydistributedwithinanenvelopethatis∝1/SNR.Combined,theseimplythatthetransformationequationsforDSLRGtoVJarevalidacrossourentirerangeofcolorsandmagnitudesinoursample.

4.1.3.SIMBAD InFigures5e,5f,and6cweessentiallyrepeattheASCCexperimentusingaheterogeneousreferencecatalogassembledfromSIMBADqueries.Boththemagnitude and color residual diagrams show a loss of precision of ~ 0.005mag.,with a few stars shiftingby asmuchas0.02mag.Althoughcertainlywithin the statisticaluncertaintiesquoted in thecatalog, thesedeviationsareoftenoutsideoftheinternalinstrumentaluncertainty,implyingthedeviationsareduetoerrorsinthecatalogmagnitudes.Wecautionthereaderthatusingaggregatecatalogs,likeblindqueriesfromSIMBAD,mayresultindegradedprecision.ThereforewesuggestthatDSLRphotometrybeperformedusingastandardreferencecataloglikeASCCor,preferably,TychoVT.


5. Conclusion and discussion

Wehaveshownthatconsumer-gradeDSLRcamerascanbeusedasaccurate(0.01mag.)photometersacrossawiderangeofmagnitudesandcolors.InthenextfewparagraphsweprovideafewcommentsconcerningDSLRphotometryanddiscusshowthereadermayalleviatetheseissues.

5.1.Onthenumberofreferencestars As discussed above, one may calibrate data using the simple method(Equation 2) using only two reference stars and the airmass-correctedversion(Equation6)withonlythreestars.However,whenusingtheselowerlimitsasaguide, the readermustbeaware thatan incorrect identification,bad instrumental magnitude, or incorrectly referenced catalog value willsignificantlydegrade (ifnot invalidate) the results.Asa ruleof thumb,werecommendsixtoninereferencestarsthatbracketthetargetobject(s)incolor,airmass,andmagnitudesothatthevaluesofk',e,andz

nmaybeinterpolated

ratherthanextrapolated. In many cases, satisfying all of these requirements is not possible. Thereadermaybetemptedtoincludefainterreferencestars,butwiththatcomeslargerstatisticaluncertainty.Inourwork,wefoundstarswithaSNR>100areoftenacceptableandstronglycautionagainstusinganystarwithaSNR<100asacalibrator.

5.2.Airmasscorrections Most of our images were taken fairly close to the zenith (with typicalairmasses not exceeding 1.2), therefore the differential extinction across theimagewasnegligible.TwoserieswiththegreatestairmassinfieldCD6Sdidshowasignificantcorrelationofresidualsasafunctionofairmass(compareequation 6). Including airmass correction in the (planar) fit did improve theresiduals significantly when compared to the (linear) color-corrected fit.In general, airmass corrections should be applied whenever the differentialairmassacrosstheentireFOVmultipliedbytheextinctioncoefficientexceedthedesiredlevelofaccuracy.

5.3.Stellarblending OfprimaryconcerntoaDSLRphotometrististheblendingofforegroundtarget/referencestarswithfainterbackgroundstars.Withthetechniquedescribedabove,starscanbecomeblendedinthreedifferentways:(1)theformalresolutionoftheopticalsetupcannotresolveblendedstars,evenunderidealatmosphericconditions,(2)defocusingtheimagecauseslightfromadjacentstarstooverlap,or(3)diurnalmotioncausesanoverlapoftrailsbetweentwonearbystars.Inallofthesecases,ifacomparisonstarisblended,itwillskewthecalibrationand,potentially,invalidatetheresults.Ifthephotometrictargetstar(s)areblended,themeasuredphotometrywillcertainlybeinvalid.


Beforeweconsiderthesethreecasesinfurtherdetail,wewishtodescribetwomethodsbywhichblendsmightbeidentified.Inalargeensembleofstars,blendswillonlyhavealimitedeffectontheresultantphotometry.Blendedstarscanbedetectedinatleasttwoways.Givenpositionsfromanastrometriccatalogand the formal resolution of the imaging setup, stars should be consideredblended if the photometric extraction apertures overlap. Software that doesthis is available from author H.B.E. by request. If the reader wishes to useanempiricalmethodfordeterminingblends,blendedstarsmaybeidentifiedbyfindingstarsthatskewthephotometryerrorhistogram.Typicallyavisualinspectionoftheplotthatcomparesmeasuredmagnitudestocatalogdatawillhave some obvious outliers. These are most frequently caused by blending,variability,orothersourcesoferror(forexample,smallclouds). Thethreesourcesofblendingdeservefurtherdiscussion.Themethodbywhichthephotometristchooses todecreaseblendingdependsonthescienceobjectivetheywishtoachieve.Inourwork,alossof25%ofoursamplewasinconsequentialaswestillobtainedphotometryon150starswithonlyten10-secondexposures.Ofthefifty-twostarsthatwerelostduetoblending,almostall of them were due to the limited resolution of the optics.We could havesimplyincreasedtheangularresolutionofoursetupbyzooming,butthenwewouldrequirealargernumberofexposures. Inthecasewherestarsareblendedduetodefocusingortrailing,themethodofresolvingtheblendbecomesmoredifficult.Inthecaseofdefocus-inducedblending, focusing the image is the obvious solution; however, defocusingensures an accurate measure of the star’s light. In the high photon regime,one shoulddecrease the exposure lengthwhileproportionally increasing thenumberofexposures.Whenanalyzingthedata,theimagesshouldbealignedand stacked. Likewise, for bright stars that become blended due to trailing,the exposure length can be decreased while the number of exposures isproportionallyincreased. Thisadvicewilllikelynotextendtothephoton-limited,faintstarregime.Indeed, theauthorsareunawareofanystudy that theoreticallydiscusses thetrade-offsbetweenchangingtheintrinsicresolution,focus,andtraillengthwhileprovidingexperimentalverificationofanypublishedclaims.Untilsuchaworkiscompleted,wesuggestthereadercarefullyconsiderthesciencetheywishtoachieveandchooseasetupbestsuitedforthejob.Theprocedurewedescribehereinisideallysuitedforwide-fieldbright-starphotometricmonitoring,butclearlynotforobservingfaintstarswithlittlephotometricvariation.

6. Acknowledgements

Theauthorswould like to thank theAAVSO’sCitizenSkyproject.B.K.acknowledges support from NSF grant DRL-0840188. B.K. thanks Dr.Doug Welch for discussions that piqued his interest in DSLR photometry.


The authors would also like to thankArne Henden for answering questionsconcerningphotometriccalibrationdatabases.Wearegratefultotheorganizersof theCitizenSkyworkshopsIandIIduringwhichwefirstdiscussed theseefforts.ThisresearchhasmadeuseoftheSIMBADdatabase,operatedatCDS,Strasbourg, France and several online collaborative tools like theAAVSO’sIRCchannel,GoogleDocs,andPastebin.

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Table 1. The 27 variable stars detected in our survey.1

Tycho VT Series Mean Typical SD Series Min. Series Max. No. Tycho Identification (mag). (mag.) (mag.) (mag.) (mag.) Sigmas Classif.

3528-2121-1 8.077 7.979 0.015 7.954 8.011 2 DA3529-1447-1 7.648 7.633 0.010 7.600 7.660 3 U3533-2577-1 5.219 5.195 0.003 5.182 5.209 5 1U3534-302-1 7.450 7.290 0.010 7.284 7.300 1 1D-3536-1939-1 7.359 7.379 0.006 7.356 7.420 7 M3536-2022-1 8.371 8.400 0.023 8.335 8.436 3 C3538-2150-1 8.436 8.415 0.015 8.351 8.483 53539-137-1 7.759 7.783 0.008 7.757 7.810 3 CU3539-1700-1 6.831 6.797 0.004 6.702 6.884 24 1U*0.513539-2623-1 8.313 8.389 0.015 8.345 8.461 5 3R3548-2346-1 7.227 7.234 0.005 7.225 7.246 2 U*2.793550-579-1 8.339 8.310 0.029 8.276 8.367 2 U*1.253551-1744-1 7.459 7.136 0.005 7.103 7.158 7 P3552-1543-1 8.438 8.464 0.014 8.427 8.513 33552-394-1 8.000 8.078 0.011 7.999 8.223 13 P3553-999-1 8.260 8.266 0.012 8.249 8.282 1 U3554-100-1 7.753 7.743 0.007 7.699 7.780 6 1U3554-1071-1 6.014 6.071 0.003 6.039 6.109 13 5U3555-686-1 7.559 7.551 0.008 7.525 7.582 4 U3564-1126-1 8.121 8.129 0.010 8.103 8.173 4 U3564-3159-1 6.231 6.215 0.003 6.151 6.256 21 5U3569-331-1 8.117 8.118 0.012 8.061 8.161 5 1U3908-1123-1 7.652 7.626 0.009 7.620 7.631 1 U3918-1829-1 5.867 5.932 0.003 5.921 5.943 4 3U3920-1660-1 8.451 8.401 0.014 8.367 8.431 2 D3920-1971-1 3.884 3.873 0.002 3.861 3.880 6 C53934-27-1 7.405 7.413 0.007 7.374 7.436 6 U1 Most stars have min./max. values that are 2+ times the typical nightly standard deviation. Of particular interest are TYC 3536-2022-1 which was labeled as “stable” in the Tycho 2 input and main catalogs. Stars TYC 3538-2150-1 and TYC 3552-1543-1 have no variability designation. All three stars have no variability designation in SIMBAD. Tycho classifications are: S=Standard, C=Stable in input/main catalog, U, P, M, R = confirmed variables. Numbers in Tycho classifications indicate variation type, see Perryman etal. (1997), and Wright etal. (2003) for designations.


Table2.Summaryoftheobservedfieldsandexposureinformation. Field* Center Near TYC No. No. No. No. Air-mass R.A. Dec. Series Images Days Stars h m ˚ ' V<8.8

CD3S“A” 1935 +5116 3568-2325-1 21 245 9 56 1.0–1.14CD4S“B” 1909 +5123 3554-275-1 6 76 3 40 1.02–1.2CD5S“C” 1843 +5130 3539-1697-1 6 76 3 48 1.05–1.34CD6S“D” 1815 +5130 3537-1538-1 7 85 4 57 1.13–1.53*Fields are 15.9 × 6.4 degrees. The instrumental magnitudes for each of the 40 series of observations are available from R.P. by request.

Figure1.Instrumentalresponsecurvesof thephotometricchannels(Photon-count)oftheCanon450Dusedinthisexperiment:(a)JohnsonVandDSLRG;(b)TychoVTandDSLRG.

(a)

(b)


Figure2.GeneralfieldpropertiesoftheCygnus-Draco15.85×6.36deg.fields,used in our experiment, and statistics for selected stars (after rejection ofblendedandvariablestars):(a)magnituderanges,Tycho2;(b)(BT–VT)colorranges;(c)Approximatespectraltypes.

(a)

(b)

(c)

Figure 3. A typical RAW star imagefromourdataset.Asmentionedabove,we use a non-tracking camera mount,hencethestarimageshowssignificanttrailing. The Red Green Blue natureof the camera’s Bayer array is clarlyvisible. The 21×13 pixel aperture isshownforreference.


Figure4.Examplesofvariableandnon-variablestarsseeninourdataset:(a)nearlyconstantstarTYC3564-3158-1andsuspected0.1mag.variableTYC3564-3159-1.(b)TYC3568-97-1andsuspected0.04mag.variableTYC3934-27-1.(c)0.1mag.suspectedvariableTYC3569-331-1andnearbystablestarTYC3560-3003-1.

(a)

(b)

(c)


Figure5(a,b,c).Residualsofthesimplecalibrationmethodasafunctionofcolor,magnitude,andcatalog:(a)Tychomagnituderesiduals;(b)Tychocolorresiduals;(c)ASCCmagnituderesiduals(figurecontinuedonnextpage).

(a)

(b)

(c)


Figure 5 (d, e, f). Residuals of the simple calibration method as a functionof color, magnitude, and catalog: (d) ASCC color residuals; (e) SIMBADmagnitude residuals; (f) SIMBAD color residuals.Aside from an increasedspread at fainter magnitudes (due to a lower SNR), there appears to be noremaining systematic residuals after application of the calibration procedurediscussedabove.Thestatisticaldistributionsofresidualsareshowntotheleftof they axes.All residuals followaGaussiandistributionwithavery smalloffset(~1mmag).Thedistributionistypifiedbyas=22mmaguncertaintywhichimprovesbynearlyafactoroftwoforstarswithV<8).ThisatteststothequalityofthecatalogandcapabilitiesoftheDSLRcamera.WebelievetheSIMBADresultsareskewedduetoinvalidcolordeterminationsinherentinainhomogeneouscatalogsystem.

(d)

(e)

(f)


Figure6.Rawinstrumentalmagnitudesasafunctionofcolorandcatalogmagnitudes.Thesedatashowverylineartrends,indicatingthetransformationmethodsdescribedaboveareapplicable:(a)ASCC2.5instrumentalmagnitudevs.cataloguemagnitude(singleexampleseries);(b)ASCC2.5residualsvs.cataloguecolor,withoutcolortransformation(singleexampleseries);(c)SIMBADresidualsvs.cataloguecolor,withoutcolortransformation(singleexampleseries).

(a) (b)

(c)

Pieri, JAAVSO Volume 40, 2012834

Stellar Photometry With DSLR: Benchmark of Two Color Correction Techniques Toward Johnson’s VJ and Tycho VT

Roger Pieri37 C rue Charles Dumont, Dijon, 21000, France; [email protected]

Received April 24, 2012; revised June 18, 2012; accepted August 17 2012

Abstract DSLRsarenowroutinelyusedformeasuringtheVmagnitudeofstarsthroughtheirGchanneloutput.ThisrequiresatransformationtoJohnsonV,usingacorrectionbasedonthecatalogue(B–V)colorindicesofthestars.Thispaperreviewstheresponsesof theinvolvedpassbandsandproposesanalternate solutionusinga synthetic filtermadebycombining the threeRGBDSLRchannels.Theassessmentofthetwotechniquesthroughexperimentationbeinguncertain,wehave chosen touse a computer simulation instead.ThissimulationcombinesthemeasuredspectralresponsesoftheDSLRchannels,theatmosphericreddening,andstarspectrafromthePickleslibrary.

1. Introduction

The recent ε Aurigae campaign (thanks to AAVSO’s Citizen Sky, hereafter “CS”)hasbeenagreatopportunitytoexperimentwiththeDSLR's(DigitalSingleLensReflex)photometrycapabilities.Wehavehadtoobserveunderverydifferentconditions,sometimesnearzenith,butalsoatverylowelevationandhighairmass,duringtheconjunctionperiodthatwasanimportantphaseoftheeclipse.ThetypicalCSDSLRobserverworkswithastandardDSLRequipped with a regular lens and mounted on a photo tripod.The author'slens is a 200 mm, f /4, but most people use shorter focal length, typically70mm, f /2.8.Accuratephotometryisachievabledowntomagnitude6withthisconfiguration.Lessaccuratedatacanbegathereddowntomagnitude8.Ideally,anobservationmadeeveryfewdays(whenweatherpermitted)wasneededtoobtaingoodcoverageofthephenomenonovertwoyears.Foranamateur this ispossibleonlynearhome,mostof the timeunderurbanskyconditions,withtypically15to20minutesofobservation.Thisalsomeansunder an extinction much worse than any professional observatory wouldencounter. Not only was neutral extinction a problem, but also reddeningathighairmasswasmakingthingsmorecomplex(unusualforprofessionalobservers).Aspecificobservingmethodanddataprocessing techniquehasbeendevisedbytheCitizenSky’sDSLRteamtofitallsuchconditions.Itisknown at CS as the “intermediate spreadsheet” method (hereafter “CSIS”)andcanbefoundontheCSwebsite(AAVSOCitizenSky2009). AsimplermethodisalsousedbyCSpeoplewhenobservationsaredonebelowairmass1.5.Itisknownasthe“beginnerspreadsheet.”Itinvolvesonly

Pieri, JAAVSO Volume 40, 2012 835

thecolorcorrectionsandnotthedifferentialextinctionacrosstheDSLRfield-of-view.

2. Present work

Initially,theauthorusedthetoolsandpublicationsprovidedbyC.Builonhiswebsite(Buil2012),hisbook(Buil1991),andthetutorialsfromCitizenSky(AAVSOCitizenSky2009),butsoondevelopedhisownsoftwarepipelinetomaketheoperationsmoreproductiveandtoexperimentwithvarioustechniquesincludingasyntheticJohnsonVfilter. Thegoalwastobetterextractusefuldatafromobservationsunderthepoorε Aur conjunction conditions. Another aim was to push the DSLR to perform at itsbestinbrightstarphotometry. TheDSLRitselfhasG-andB-colorfilterswhichdonotmatchthestandardCousins-JohnsonBandVpassbands(hereafterBJandVJ).TheDSLRRchannelistoofarfromtheCousinsRctobefaithfullytransformed.AspecifictransformationandextinctioncorrectiontechniquehasbeendevisedtotakecareofboththeGpassbandandtheCSamateurcontext(HendenandKaitchuck1982;KloppenborgandPearson2011).ThisCSIStechniqueisbasedonthecatalogue(B–V)andV-magnitudeofastar“ensemble”thatdeterminestherelatedcorrectioncoefficients. In the CSIS the differential neutral extinction is determined through amappingofthemagnitudedeviationsofstarsofalargeensembledistributedin the DSLR field-of-view (FOV). To do this, the fully “color corrected”instrumentalmagnitudeofthestarsisthencomparedtothecataloguemagnitudeof the stars. The resulting magnitude differences that are a function of thedifferentialairmassdeterminetheneutralextinctiongradientacrosstheFOV. Statistics have been extracted from the ε Aur observations and critical cases have been identified in this CSIS technique. The single-equationsystem(Equation5)usedbytheCSIShassomedrawbacksdependingonthedistributionofstars.ToovercomethatissuetheauthorsoonconsideredacolorcorrectiontechniqueindependentofthecataloguedatausinganRGBsyntheticfilterequivalenttoVJorVT(hereafter“VSF”).Itisimplementedbycombiningthe three RGB channel signals of the DSLR. The first experiments showedinterestingpossibilitiesbutitwasobviousthatanaccurateassessmentofthesetechniqueswasdifficulttoachievethroughobservations.Thenitwasdecidedtouseacomputersimulationforthatstudy. SeveraloptionsofprocessingoftheneutralpartoftheextinctionintheVSFtechniqueremainunderstudy.Theauthorplanstoaddressitinafuturepaperbasedonthebestoption. Bytheway,thepresentpaperaddressesonlythecoloraspectofboththeCSISandtheauthor’sVSFtechnique.ForsuchstudyonlytheDSLRresponseandtheslopeof theatmospheretransmissioncurveareusedinadifferentialphotometryschemewhereallstarsareatthesameairmass.


Carrying out such a simulation needed a library of stellar spectra. ThePickleslibrary(Pickles1998)hasbeenfoundtomeettheneedwithits131starsfromOtoM,atallluminositiesandseverallevelsofabundance.Otherinspiringsources have been the many papers from Bessell: in “UBVRI passbands”(Bessell1990)heanalyzed the issuesofvarious filter implementationsusedunderseveralphotometricsystems.Thepaperincludesasyntheticmagnitudecalculationusing theVilnius spectra library.Theapproach isvery similar towhatisreportedinthispaper.Hislastpaperhasaninterestingappendixpointingoutsomeissuesofsuchbroadpassbands(BessellandMurphy2011). Thepaperfrom(TokunagaandVacca2005),thephotometryintroductionof(Romanishin2006),andastudyofthecalibrationofTycho-2andJohnsonsystems(Apellániz2006)havealsobeenveryinformative. AnotherimportantsourcefortheDSLRapplicationistheHipparcosmission(Perrymanet al.1997).LookingatthevarioussystempassbandsrevealedthattheTychoVTpassbandiscomparabletotheDSLRgreenresponse.InadditiontheTycho-2catalogue(Høget al.2000)catalogueisauniform,veryaccurate,and reasonablyprecise reference.Thisopenedanewpossibility thatwillbeanalyzedhereafterandcomparedtoJohnsonVJusingboththeCSISandtheVSFtechniques. AtthispointtheauthorwouldliketodiscusstheaccuracyofthecataloguescomparedtowhatcanbeobtainedthroughDSLRphotometrytechniques.Suchtechniques,basedonmappingofmagnitudedifferences,areverysensitivetothecatalogueerrors.Fortunately,DSLRshavealargeFOVthatallowsonetoworkwithalargeensembleofstars(50to100starsaccessibleina6×4degreefield).ThisaveragesbothcatalogueerrorsandtheimperfectcolordistributionintheFOV.Ata1000signal-to-noiseratiotheDSLRprovidesresultsreproduciblewithinafewmillimagnitudes.Mostcatalogueshavelargeruncertainties,andfromcataloguetocataloguesuchuncertaintiesareoftenmuchlarger;thiscouldaffect the determination of both the color transformation coefficient and thedifferentialneutralextinctionwiththeCSIS(asitisbasedonamappingofitfromanensembleofstars).

3. Color Passband: DSLR’s RGB versus Johnson’s VJ and Tycho-2 VT

TheDSLRR,G,Bchannel responses are shown inFigure1.Theyhavebeenobtainedfromaclearday,sunlightobservationusingaslitandgratingmountedinfrontoftheDSLRlens,thencorrectedfromthestandardASTMsunspectrumat1.5airmass(ASTMInternational2008)andtheRGBbalanceofthegrating.ItistobenotedthatDSLRcurvesaretheresponsesofthefilterstack(R,G,B,IR,andUVcut)plusthesensorandthelens.ThelinearRAWoutput of the DSLR has been used; that excludes any processing from theDSLR—inparticular,anygammaapplicationoranytransformationtosRGBorothercolorprofile.TheDSLRwasastandardCanon450DwithaCMOS


sensor,14bits,equippedwithaNikkor85mmlens.ItsIRandotherfilterstackhasnotbeenmodified. IntheUBVRI(andother)photometricsystems(Bessell1990),magnitudesare calculated from the photon-count from photometric chains of severalpassbands.Figure2showstheJohnsonV(hereafter“VJ”)passbandanditsrelationshipwiththeDSLRGchannel.TheversionusedasreferenceinthisstudyistheonerecommendedinthePickles(Pickles1998)spectralibrary.ThisversionisverysimilartotheonerecommendedbytheCDS.Theyareusedinanumberofpublications,butotherversionsalsoexist(BessellandMurphy2011). Figure3showstherelationshipbetweentheTycho-2VTpassbanddefinition(Apellániz2006)andtheDSLRGchannelresponsecurve. OtherDSLRcolorchannelsresponsescouldbeseenatthewebsiteofC.Buil(Buil2012).Theyareverysimilar.Apparently,therearenolargedifferencesbetweenrecentDSLRorDSC(digitalstillcameras;largedifferencesmaybefoundinoldercameras). ThecolorfilterarrayoftheDSLRisoftheBayertype(Bayer1975)withasquareRG/GBarrangement.ThatmeanstheGsignalisobtainedfromtwosub-pixelsinsteadofonlyoneforRandB.Inaddition,asshowninFigure1,thetransmissionoftheredfilterismuchlowerthanGandB.AsaresulttheSNRoftheGchannelismuchhigherthantheBand,inparticular,theRchannel.TheRAWresultingcolorbalanceismoreorlessCIE(CommissionInternationaledel'Eclairage)typical(Greenet al.2002).Inmostcommonusage(sRGBandJpegoutput)theRGBlevelsarerealignedto1,1,1.Thentherepresentationisnon-linear(0.45gamma)codedon8bitsandtosomecolorprofilelikesRGB.ThisstudyusesonlythelinearRAWoutputofR,G=(G1+G2)/2andBdata(saidADUs,proportional tophoton-count,hereafterallphoto-countdataaredenotedas“G”,italicizeduppercase,andmagnitudesas“Gm”). The instrumentalmagnitude,Gm, isusuallycalculatedwith theequation(Equation3)fromtheDSLRG-channeloutput,G,thentransformedtoVJGtm usingEquation4.IfwecomparetheGresponsetotheVJresponse(Figure2),thereisalargecommonsurfacebetweenthemboth,butalsosignificantdifferences. Thebluesideroll-offisthelargestsignificantdifference.ThecentroidoftheGresponseisat530nmandtheVJoneat542nm.Buttheblueroll-offoftheGresponseisshifted26nmtothebluecomparedtothesteeproll-offoftheVJcurve.Inadditionthereisablueleakatthefootofthecurvebetween450and400nm. Ontheredsidethedifferenceislessimportantandopposite:missingredinsteadoftoomuchblue.TheredsideGroll-offisshiftedtothebluebyabout5nm.Figure3showstheTychoVTpassbandwhichismuchmoresimilartotheGchannel.Thecentroidspositionsaredifferentbyonly2nm.Theresultingcolorcorrectionbetweenbothshouldbeminimal.WewillalsostudythatcaseasitoffersarealopportunityforDSLRphotometry.


4. Atmosphere transmission

The bandwidths of all DSLR-involved passbands are not small. Besidestheimpactofthemeanextinctionatthecentroid,thepassband’sinternalcolorbalance is affected by the atmosphere transmission variation as a functionof the wavelength (essentially the slope of this function). The result is theproduct of both: the camera response S(l) and the atmosphere transmissionT(l).Thismore-or-lessmovestheresultingcentroidtothered.Theatmosphereaffects all passbands including the references, Johnson’sVJ, andTychoVT.The atmosphere attenuates the short wavelengths more than the long ones.This is shown in Figure 5, extracted from the Moon’s solar irradiance table(Desvignes 1991).That effect is weighted by the length of the light path intheatmosphereknownas theairmassnumber(AM),after theBeer-Lambert-Bouguerequation:

T(l,AM)=e–e(l)AM (1)

WheretheairmassAMisafunctionofthestarzenithaldistancez(orelevationh=90–z),ande(l)istheextinctioncoefficient.IntheDesvignestablee=0.23atl=550nm.ItcouldalsobeextractedfromthesolarirradianceatAM0andAM1.5 from theASTMstandard (ASTMInternational2008).The solarenergystandardsbetterfitoururbanamateurskyconditionsthanthedatafromprofessionalobservatories.

M=1/cos(z)AM=M–0.0018167×(M–1)–0.002875×(M–1)2–0.0008083×(M–1)3 (2)

Where M is the airmass in a planar homogeneous atmosphere model (validdownto10degreeselevation),andAMthecorrectedairmassaftertheHardie’sapproximation (valid down to 5 degrees elevation) (Ilovaisky 2006). Theseequationsarenotused in thesimulationwhere the inputof the transmissiontableisdirectlyAM. Inthefollowingsimulationonlythechromaticpartoftheextinctionisusedandstudied(thetransmissionslope).TheneutralpartofitanditsdifferentialeffectintheDSLRFOViseliminatedbythedifferentialphotometryandthefactallstarsaresetatthesameairmassinthissimulation.

5. CSIS color transformation from the DSLR Gm, instrumental magnitudes, to Gtm, VJ, or VT magnitudes

The CSIS color transformation (Henden 2000) is a linear interpolationbetweenthecolorindicesofthestars,thetargetoneandatleasttworeferencestars(an“ensemble”beingbetter).Thecolorindexisthemagnitudedifferencebetween two passbands like (B3 – V). (Pickles 1998; B3 denotes a specific


Johnson B filter adopted for the Pickles spectra. It is not far from the filterrecommendedbytheCDS.)Themagnitudedifferencefromathirdpassbandislinearlyinterpolatedfromtheknowncolorindices.Theinterpolationcoefficient“kD”isexpectedtobespecifictoagivenDSLR.Asimilartermshallalsoaccountforthereddeningduetothechromaticpartoftheatmosphericextinction“kK”.Itshallbereadjustedforeachstarfieldasafunctionofitsdistanceangletothezenith.Within40degreesofthezenithitaccountsforabout2millimagnitudesonlywithintheusual±0.7(B–V)range,thenitcouldbeignored.Atairmass1.5 ~ 4 the impact shall be taken into account (3 ~ 30 millimagnitudes).

Gm=m0–2.5log(G/G0) (3)Gtmi=Gmi+zp+kD(B3 – V )i+kK(B3 – V)i+kNXi (4)

GmistheinstrumentalmagnitudefromtheGandG0photon-countissuedfromthegreenchanneloftheDSLRrespectivelyforatargetstarandacomparisonstar.(B3 – V )isthecataloguecolorindexofthestar(i).Gtmisthetransformedmagnitudeof the star. zp is the zero-point, themagnitude constant from theinstrument.InagivenobservationkDandkKcan’tbeseparatedwhensolvingtheequationsystem(Equation5)andshallbereplacedbykC=kD+kK.IntheDSLRFOV,Xiisthedifferentialairmassofthestar(i)fromthereferencestarorensemble. InthesimulationreportedinthispaperG0isthephoton-countofanA0Vstarofmagnitudem0=0and(B3 – V )~0resultinginzp~0.ThenallstarsoftheFOVbeingsetatthesameairmass,allXi=0andkNarenotapplicable. Fromactualobservations, thecoefficientsforagivenDSLRandagivenFOV are determined from the catalogue values (B3 – V ) and Vjm of severalreferencestarsandtheirmeasuredGmvalues(orhereinafterBT – VTandVTminthecaseofTycho-2).

Vjmi=Gmi+zp+kc(B3 – V )i+kNXi (5)

ApplyingtherelationEquation5totheobservationofmorethanthreestars(i)formsanoverdeterminedequationsystemthatissolvedusingtheleastsquareerror algorithm. This method is used to determine zp, kC, and kN from thisensembleofstars.OnlykCisusedinthereportedsimulation. Characterizing the DSLR kD through observations instead of throughsimulation is tricky.Suchobservationsshouldbemadeunderverygoodskyconditions,nearthezenith,usingwell-documented,stablestarsofamatching(B – V)range,athighSNR(>300),andrepeatedseveraltimes.TheextinctionshouldbeindependentlycheckedusingtheBouguer’slinemethod(Ilovaisky2006). If the resulting extinction parameters are far from standard and/orirregular as a function of the star’s elevation, the sky conditions should beconsideredinadequateforacalibration.


6. Definition of a DSLR “VSF” synthetic filter delivering a VJ- or VT-like magnitude

Fromtheanalysisof thewavelength responseof theDSLRchannelswecandefineanothertechniquetoemulateaJohnsonVJchain.ThewavelengthdifferencebetweentheblueleakandtheBresponsecentroids,andsimilarlyforthered,leadsonetothinkthatacompensationwouldbepossibleintheformofasyntheticfiltercombiningtheRGBchannels:

Gc=G+a R–b B (6)

Gcm=–2.5log(Gc/G0) (7)

WhereG,R,Barethephoton-count(orADUs)fromtheDSLRrawoutput,GcandG0aretherespectivephoton-countsofatargetstarandtheA0Vcomparisonstar(m=0,B – V~0),bothVSF-filtered,andGcmisthecorrectedmagnitudeofthetarget. InthefollowingsimulationtheaandbcoefficientsareoptimizedfromtheRGBoutputsoftheDSLRG,R,B,andthestandardfilteroutput,Vj,ofthePicklesstarsspectra(allphoton-count;orVTinthecaseofTycho-2).Thisoptimizationof(a,b)acrosstheHRdiagramisdonebysolvingtheoverdeterminedequationsystemformedfromtherelation(Equation8)usingtheensembleofstars(i).

Vji=k(Gi+aRi–bBi ) (8)

ItisnotrecommendedtoapplyEquation8todataobtainedfromobservations.The various errors due to the observational conditions and the catalogueuncertaintiescanhaveasignificantimpactonthe(a,b)coefficients.SucherrorscanunbalancethecorrectionsfromtheBandRchannels.Thiscouldresultinagoodcorrectionforagivenstarsetbutonethatisnotoptimalacrosstheoverall(B–V)range.It’sbettertousethecoefficientsdeterminedfromtheRGBpass-bands. Theway(a,b)workscanbeunderstoodascontrollingthecentroidandthebandwidthoftheVSF.When(a,b)varyinoppositedirectionstheycontrolthebandwidth,otherwisetheyshiftthecentroidoftheVSF. This G,R,B combination results in a synthetic filter (VSF) which has aresponsesimilartoVJ(orVT)inthevisibledomain.TheVSFpassbandshapeisnotexactlythesameasVJbutrespondssimilarlytothespectrumcontinuum(Figure18).TheVSFresponsetospecificfeaturesofthespectra,likeBalmer’slinesofbluestarsormolecularbandsoftheredones,coulddiffer(Figure4).A first check has been made using the black body spectrum at various startemperatureswithexcellentresults(withinonemillimagnitude). TheproposedVSFtechniquehasalsobeenextensivelytestedonthestarfieldoftheeAurcampaignwithexcellentresults.Undergoodskyconditionsthestandarddeviationwithinanensembleoffivestars(B–Vfrom–0.18to1.22)


andtheircataloguevalueswasoftenaslowasacoupleofmillimagnitudes.Butthatfieldhadnospectrum-criticalstar.Next,therearefewreferencestarsofvarioustypeshavingVJmagnitudesknownwithhighaccuracyinasinglefieldof5~15degrees(DSLRFOV).Ithasbeenjudgedeasier,moreaccurate,andinformativetoassessthistechniquethroughacomputersimulationusingthecoherentPicklesspectralibraryandthemeasuredRGBresponsesoftheDSLR. IntheCSIStransformationthechromaticpartoftheextinctionisincludedinkC,andweseethatitshallbesetbeforethedeterminationofthedifferentialneutralextinctionintheDSLRFOV. ThiscanbeachievedwiththeVSFtechniquebyadaptingthecolorbalanceof thesyntheticfilter.This is justmakingthe(a,b)coefficientsadaptivetoameasureoftheatmosphericreddening(Equation9).TheBc/GcratiooftheB,GoutputsoftheDSLRisanexcellentmeasureofit.Itisverystableduringanobservationandlooksmuchmorereliablethananysinglechanneloutput.

a=a0+a1Bc/Gc b=b0+b1 Bc/Gc (9)

TheBc/GcratiousedisthatofareferencestarintheFOVorofanensemblecenteredonthe(B–V)range.ThisatmosphericreddeningcorrectionshouldnotbeconfusedwiththemainfiltersynthesisoperatedbyEquation6.Itproducesonly a limited centroid shift of the synthetic filter that compensates for thereddening,andafirstorderlinkto(a,b)hasbeenfoundaccurateenoughfortheCanon450D.AsecondordercouldbeneededforsomeolderDSLRshavingalargeblueleakintotheGchannel.

7. Pickles spectra library

ThePickleslibraryincludes131spectraofstarswith(B3 – V )from–0.38to1.816andO5toM10spectraltypes.AllluminosityclassesItoVarerepresented.Thespectracomprisewavelengths1150Åto25000Åataresolutionofabout500(Dl/l).Thelibraryhasbeenconstructedbycombiningthedatafromsixteenother libraries with a dedicated combination and verification methodology.DetailsmaybefoundinPickles(1998). ForthepurposeoftheDSLRsimulationtherangefrom350nmto750nmhas been extracted from the original data (Figure 4). The library providescalibrated spectra in energy density per Ångstrom; then the flux has to beconvertedtophoton-count.Theoriginalnormalizationat5556ÅofthespectrahasbeenreadjustedfornormalizingtheoutputoftheVJ(orVT)passbandtozeromagnitudeatzeroairmassforallstars.ThismakestheassumptiontheVJmagnitudesaredefinedontopoftheatmosphereaftertheJohnsondefinition(Bessell1990). MoststarsofMspectraltypeshowlargecolortransformationerrors.Thisisduetotheirspectrumhavinglargeabsorptionmolecularbandsresultingintheir(B3 – V )colorsnolongerreflectingtheblack-bodyfluxandpredictingthe


correctfluxcorrectiontoVJ.ForMstars,amagnitudecorrectionbasedonthe(V–Rc)colorismoreappropriate(RcisnotaccessibletoDSLRexceptifIRcutandIRdyefiltersareremoved).Mstarshavebeenprocessedseparatelyand110O-to-Kstarsremaininthemainanalysis. The ninth star of the library ofA0V spectral type has been used as thecomparisonstar(G0photon-count)inthemagnitudecomputations.ItsVJ(VT)magnitudehasbeensettozerobutthecolorindexdeterminedbyitsspectrumis0.015.Thisinducessomefewmillimagnitudesglobalshiftoftheendresult.

8. Computer simulation of the DSLR outputs and color processing

ThesimulationisjustthesoftwareimplementationofEquation10toeachsystempassbandofthatstudy:

GADU=kNp=—hck ∫

llF

l(l)T(l,Am)S(l)dl (10)

whereGisanyofRGBchanneloutputsoftheDSLR,kisthesensitivity(orcalibration factor) inADU/photon, andNp is thephoton-count.The spectralenergydistribution,F(l),ofthePicklesspectraistransformedinthephoton-countaslF

l(l)/hc.

S(l)istheoverallphotoniccameraresponseandT(l,Am)istheatmospheretransmission. S(l)issuccessivelysettotheresponseofthefivepassbandsVJ,VT,R,G,B,thecollectingareabeingarbitrarilysetat1cm2. InthisprocessthesoftwarecomputesGADUofallstarsatairmasszeroandnormalizesF

l(l) toputall starmagnitudesVjmorVTm tozeroat this level

usingthereferencepassbandsVJorVT.ThenB3 jmorBTmandtherelatedcolorindexesarecomputedforcheckingagainsttheoriginallibraryvalues. Next theGADUofallstarsare re-evaluatedateach targetedairmassfromthenormalizedF

l(l),theatmospheretransmissionT(l,Am),andthepassband

responseS(l).TheresultsafterintegrationarethenewVjorVTandR, G, B photon-counts. The lastphase is tocompute theendresultsofboth techniquesfromthephoton-countsusingEquations3–4and6–7.TheresultsarethefinalmagnitudesVjm(thereference,orVTm),Gtm,Gcm(thecorrectedresults). Hereweshouldbringtomindthatallstarsareatthesameairmassunderevaluation.Nodifferentialneutral extinction is involved in the result.Theseresults are the deviations due to the combined camera passbands and theatmospheric reddening, depending on the star’s color. They are graphicallyshownbelow. InafirstpassthesoftwareisalsousedtocomputeonlyR,G,BandcalibratethecoefficientskC,a,andbusingEquations5and8. Allthatcomputingchain,uptoEquation3orEquation7,usesthenotionoftransmissionandphoton-countinsteadofthelogarithmicprocessingusual


inastronomy.ThisisneededastheVSFtechniqueisadditiveatthephoton-countlevelandcannotbeprocessedusinglogs. ThissimulationhasbeenimplementedintheAPLlanguageandperformedunderaDyalogAPLsystem.

9. Benchmark results

9.1.Airmass1instrumentalresultsunderbothVJandVTsystems Johnson System—Figure 6 shows the respective instrumental magnitudedeviationsatairmass1oftheJohnsonVJpassband,Vjm,andtheDSLRgreenchannel,Gm.Vjmwasnormalizedto0atairmass0.Thedeviationsaremoreorlessalinearfunctionof(B3–V ).Thepeak-to-peakdeviationforGmisabout260mmgacrossthecolorindexrangeof2.2magnitudes.Theslopeisroughly0.118.ThisGm(B3–V )curveiswhatweshallusetotransformtoJohnsonVJ. Thereisasetofoutliersabove(B3–V )=1.1magnitude.ThosearetheMstars,whicharebluerthantheKstars,althoughtheyarecooler,duetolargemolecularabsorptionbandsintheirspectra.TheireffectivetemperatureismuchlowerthanexpectedfromtheircolorindexdefinedbytheBJandVJpassbands.Inthefollowingtheyareexcludedfromthemainanalysis.Thisissuehasbeendenoted in the Hipparcos and Tycho report (Perryman et al. 1997) and theauthorsrecommendnottotransformtheMstarmagnitudes(likeTycho,wecanonlyworkwithBandV,astheDSLRRistoofarfromRc). TheVjmJohnsonoutputitselfshowsasmalldeviationatairmass1duetothe star color—about10millimagnitudesacross the range.This is smallbutwouldneedalinearcorrectionwhenprecisephotometryisrequired. Tycho System—Figure7 shows the comparativedeviationsof theTychoVT passband VTm and the DSLR green channel Gm, without correction, atairmass1.VTmisnormalizedto0atairmass0.TheVTmdeviationatairmass1issomewhatlarger(19millimagnitudes)thanVjm.ThisisduetothelargerandbluerVTpassband.Theresponseof theDSLRgreenchannelshowsamuchsmaller deviation than under the Johnson system (23 millimagnitudes peak-to-peakinsteadof260).Thisconfirmstheanalysis(section3)madefromtheresponsecurvesandtheircentroids.TheoutliersaretheMstarsandafewKstarsasseenintheVJplot(Figure6),butwithasmallerscatter. This confirmation is important, showing the Tycho-2 catalogue shouldbe the reference for DSLR photometry. This catalogue is accurate in themagnituderangeaccessiblewithouta telescopeandprovideswell-quantifieduncertainties.

9.2.Airmass1to4andbothVJandVTpassbands Figures8and9,respectively,showtheresponsesof theJohnsonVJandTychoVTpassbandsatairmasses0,1,and4.Theyshowthestrongimpactoftheatmosphericreddeningevenonsuchstandardfilters.Atairmass4,thepeak-


to-peakerrorsare,respectively,40and65millimagnitudesforVjmandVTm.Theairmasscolorshiftneedsacompensationforthestandardpassbands. ThefollowingsectionscomparetheCSISandVSFdeviationsatairmass1and4underVJandVT.

9.3.Johnson’sVJ—airmass1and4—CSISandVSFtechniques Figures10to13showthedeviationsofGtmandGcmforthe110starsoftypeO-to-K. CSIS—TheCSIStransformationresult,Gtm(Figures10and12)hasbeenoptimizedwith respectively kC=0.135 and0.098 for airmass 1 and4.This0.135valueisingoodagreementwiththeonetypicallyused,atzenith,foroureAurobservations. Thedeviationpatternissimilaratbothairmassesandformstwolinesfroma maximum around 5 millimagnitudes at (B3–V ) = 0.33 and a range of 20millimagnitudes.Usingslightlydifferentcoefficientsforthecolorindexranges–0.4~0.33and0.33~1.8(twodifferentslopes)wouldimproveit.Thisshouldreducetheerrorrangetoabout8millimagnitudesexceptafewoutliers.ThoseoutliersareK-typestarsthatshowsomeproblemssimilartotheMtypes.OnthebluesidethereareoneB3IandoneF5Ioutlierwithoutclearreasontodeviate,althoughtheadditionalvioletfluxinsupergiantsissuspectedtobethecause. VSF—TheVSFresult,Gcm(Figures11and13)hasbeenoptimizedwith,respectively,(a=0.284,b=0.224)and(a=0.149,b=0.244)forairmass1and4.Thisisjusttheexperimentalvalueforb,andasomewhathighervaluefora.Buttheredcorrectioncoefficienthasalargevariabilitydependingontheexperimentalconditionsduetoitsweakeffect.aequaltoorabove0.284isnotuncommon. The airmass 1 deviation pattern differs from Gtm with a well containedsection above (B3–V ) = 0.3 within 7 millimagnitudes and no K outlier.Atairmass 1 the section below 0.3 shows more dispersed results (within 15millimagnitudes)oftheOBAstars. Thepatternatairmass4isreducedtoa12millimagnituderangebuthasthesameshapeasairmass1.BotharebettercontainedthanGtm,theresultoftheCSIStransformation.

9.4.TychoVT—airmass1and4—CSISandVSFtechniques Figures14to17showthedeviationsofGtmandGcmforthe110starsoftypeO-to-K. CSIS—TheCSIStransformationresult,Gtm(Figures14and15),hasbeenoptimizedwith,respectively,kC=0.009and–0.019forairmass1and4.This0.009iswellinagreementwiththevaluetypicallyused,atzenith,inanothermassivesurveyexperimentbasedonTycho-2. Thepatternofthedeviationsatairmass1ismoreorlesssimilartothatof VJ but with a reduced amplitude of 10 millimagnitudes excluding the


usualoutliers.Thepivotpointhasmovedabout(B3–V )=0.8.Theoutliersalsoshowareduceddeviation. TheoverallimprovementfromtheVJsystemismorethanafactortwo.Atairmass4,thepatternamplitudeisfurtherreduced,butdominatedbytheoutliers. VSF—TheVSFresult,Gcm(Figures16and17)hasbeenoptimizedwith,respectively,(a=–0.085,b=0.073)and(a=–0.136,b=0.030)forairmass1and4. Thedeviationpatternsatairmass1and4arenearlyidenticalshowingthelowestamplitudeofallabout8millimagnitudes(excludingsomeoutliers).AsintheVJsystem,usingVSF,thelateKstarsarenoproblemandthedispersionsarenotclearlylinkedtoanyspecificspectraltype.Atthatlevelofacoupleofmillimagnitudesitisverypossibleweareseeinglimitationsduetothelibrary.

10. Discussion of the simulation results

Theaccuracyofthesimulationresultsdependsuponthreeitems:thespectralibrary,thepassbandresponses,andtheatmosphereextinctionmodel.Thelastisjustastandardmodel,andtheobservationsclearlyshowlargedeviationsfromsuchamodel.TheBc / Gcratiodependencytotheairmassisusuallystableandtheneutralextinctionmuchmorevariable.Thisistheresultofthevariabilityofthehighaerosolcontentofoururbanskies.SuchaneutralcomponenthasnoimpactandanyslopechangeofT (l,Am)isacolorbalancedifferencethatwouldjustaffectthecorrectioncoefficients,nottheenderrorlevelshownbythesimulation(thechromaticanddifferentialneutralcorrectionsareindependentintheVSFtechnique). ThenextpointistheDSLRresponsecurveaccuracy.ThepassbandshavebeentestedbycomparingthesimulatedRGBoutputswiththephysicalRGBoutputs of theDSLRandhavebeen found tobewithin a coupleof percentandcorrected.Theresponsecurveshavebeenmeasuredusingthreedifferentreference light sources and found similar. The differences impacted thecorrectioncoefficientbylessthan2%. The spectral features: lines, bands, but also some small differences inlargebandsofthecontinuum,areexpectedtobethereasonforthestar-to-stardeviationsseen in thesimulation results.ThenwehaveastandarddeviationfromPickles(hereafterSD)ateachwavelengththatranksfrom5%to0.5%.Butwedon’tknowthecorrelationfromonewavelengthtothenextthatcouldformsuchsmall“bumps”ofthecontinuum(afewpercent)overabandwidthlarge enough to interact with the roll-off of the DSLR passbands. In thehypothesis,wherewepropagatethoseSDswithoutanycorrelation,wewillgetaworseSDof3millimagnitudesattheendwhichseemssomewhatoptimisticwithregardstothesimulationresults.Then,ifwetaketheworstcasepossiblecorrelation,wewillgetadeviationof50millimagnitudeswhichisobviously


fartoolargeandunlikely.Thisaspectwouldneedadeeperstudyofthelibraryconstruction,whichcombinesavariablenumberoforiginalspectradependingthewavelengthandthestarspectraltype.Therearecasesbasedonafewdataonly.Anyhow,thePickleslibraryisanexcellentresourceandthebestofthosetestedbytheauthorforthiswork. The VSF technique has been extensively used during the ε Aur campaign withgoodresults (reportscanbe foundunderPROCatCitizenSkyand theAAVSO). It permits us to achieve a fully VJ color response of the DSLRindependentlyfromthedifferentialneutralextinctioncorrection(andothererrorsources).ThisavoidspossiblecontaminationfromotherfactorsthatexistswiththeCSIStransformation.ThisCSISissuedependsonthestarcolordistributionandtheirpositioninthefieldofview.TheVSFtechniqueisalsoindependentofthecataloguesafteritscalibrationisset. The VSF technique has been very effective when we had to observe ε Aur at low elevation during the conjunction. It is also very helpful in cases ofcolorchangeofavariable.ThishasbeenrecentlythecaseofzAur,forwhichinterestingresultshavebeengathered. AfurtherimprovementoftheDSLRphotometrywillbetousetheTycho-2 catalogue as a primary reduction reference. The DSLR instrumental colorcorrection isvery lowunder thisphotometric system;only thehighairmasschromaticeffectissignificant.Thisshallfurtherimprovetheaccuracyofbothcolor and neutral extinction corrections thanks to the better uniformity andaccuracy of this catalogue. If a Johnson’s Vjm is needed the end result canbeconvertedusingtheTychorecommendedmethods(Perrymanet al.1997).Amoredetailed tableof corrections as a functionofBT–VT is provided in(Bessell2000).

11. Conclusion

Itispossibletoachieveacolorcorrectionoftheinstrumentalmagnitudesof a DSLR to Vj or VT, within ±5 millimagnitudes, with both the CSIStransformationandtheVSFtechnique.TheCSIStransformationwouldneedsomerefinement(secondordercoefficient,ortwoslopes)toachieveitacrossa wide B–V range under the Johnson system.The color and airmass of thereferencestarsusedintheCSISshouldbewell-balancedandbracketthetargetstarsinallaspects. M-starmagnitudesarenotwell-transformablefromtheDSLRpassbands,withpossibleerrorsaslargeas60millimagnitudes.SomelateKstarscouldalso deviate by 20 millimagnitudes after the CSIS transformation. Theluminosityandtheabundanceofthestarsseemnottobesignificantfactorsofdeviation. The VSF technique provides the best accuracy, and is independent ofthecatalogue(B–V),ofthedifferentialneutralextinctionandothervarious


errorsources.ItshowsnospecificerrorfortheKstarsandgenerallyworksbetterwith red stars.Using it under theTycho-2 systemprovides a furtherimprovement, reducing the color related errors and also providing a moreuniform reference for determining the differential neutral extinction in thefieldofviewoftheDSLR.


TheauthorwouldliketothanktheCitizenSkystafffortheirinitiativeandsupport during the ε Aur campaign, Brian Kloppenborg for his support and involvementinDSLRphotometry,andtherefereeMikeBessellforhisusefulcommentsonthepaper. This work has made use of the SIMBAD database, operated at CDS,Strasbourg,France.

References

AAVSO Citizen Sky. 2009, “DSLR Photometry Tutorial” (http://www.citizensky.org/content/dslr-documentation-and-reduction).

ASTM International. 2008, “ASTM G173—03(2008) Standard Tables forReferenceSolarSpectralIrradiances:DirectNormalandHemisphericalon37°TiltedSurface”(http://www.astm.org/Standards/G173.htm).

Bayer,B.1975,ColorImagingArray,U.S.Patent3,971,065.Bessell,M.S.1990,Publ. Astron. Soc. Pacific,102,1181.Bessell,M.S.2000,Publ. Astron. Soc. Pacific,112,961.Bessell,M.S., and Murphy, S. 2011, Publ. Astron. Soc. Pacific (accepted),

arXiv:1112.2698v1.Buil,C.1991,CCD Astronomy,Willmann-Bell,Richmond,VA.Buil,C. 2012, “Spectroscopy, CCD and Astronomy” (http://www.astrosurf.

com/buil).Desvignes, F. 1991, Rayonnements Optiques: Radiométrie, Photométrie,

Masson,Paris.Green, P., and MacDonald, L. (eds.). 2002, Colour Engineering: Achieving

Device Independent Colour, John Wiley & Sons, Ltd., Chichester,England.

Henden,A.A.2000,J. Amer. Assoc. Var. Star Obs.,29,35.Henden,A.A.,andKaitchuck,R.H.1982,Astronomical Photometry,Willmann-

Bell,Richmond,VA.Høg,E.,et al.2000,Astron. Astrophys.,357,367.Ilovaisky,S.2006,"OpticalPhotometry"(www.obs-hp.fr/ecole-ete/Photometry.

pdf).Kloppenborg,B.,andPearson,T.2011,Sky & Telescope,121,64(April).MaízApellániz,J.2006,Astron. J.,131,1184.


Perryman,M.A.C.,EuropeanSpaceAgencySpaceScienceDepartment,andtheHipparcosSciencTeam.1997,The Hipparcos and Tycho Catalogues,ESA SP-1200 (VizieR On-line Data Catalog: 1/239), ESA PublicationsDivision,Noordwiijk,TheNetherlands.

Pickles,A.J.1998,Publ. Astron. Soc. Pacific,110,863.Romanishin, W. 2006, An Introduction to Astronomical Photometry Using

CCDs,Univ.Oklahoma,Norman,OK.Tokunaga,A.T.,andVacca,W.D.2005,Publ. Astron. Soc. Pacific,117,421.

Figure1.PhotonicresponseoftheRGBchannelsoftheCanon450DDSLR(arbitraryunitsproportionaltoS(l)ofequation10).

S(l

) A.U

.

Wavelength (nm)

Table1.CSISandVSFcoefficientstotheVJandVTphotometricsystems.*

AM Gc mean Bc /Gc mean VJ/kc VJ/a VJ/b VT/kc VT/a VT/b

0 1027 0.805 0.145 0.340 0.217 0.020 –0.064 0.089 1 800 0.750 0.135 0.284 0.224 0.009 –0.085 0.073 2 624 0.701 0.125 0.235 0.231 –0.002 –0.103 0.058 3 488 0.656 0.110 0.190 0.238 –0.012 –0.121 0.045 4 382 0.616 0.098 0.149 0.244 –0.019 –0.136 0.030*Table 1 shows the various coefficients used in the simulation at various airmasses. “Gc mean” and “Bc /Gc mean” are the mean output intensities of the DSLR channels for the O-to-K spectra “ensemble”(orofaF6Vstar).Theextinctioncoefficientusedisε=0.23at550nm.TheBc /Gc ratio is used to measure the atmospheric reddening as a function of the airmass, AM. Gc mean results from the atmosphere transmission for the G channel after the Moon’s model (Desvignes 1991). “kc”, “a”, and “b” are the correction coefficients defined in sections 3 and 4, applied to both Johnson and Tycho standards. The values at AM0 are the correction coefficients of the DSLR G channel passband alone, normally invariant.


Figure 4. Pickles library (Pickles1998), samples of M3V andA0V starsof the131 spectranormalizedat555.6nm. Spectra are in energy density perwavelength(nm).

Figure 5. Transmission factor of theatmosphere at airmasses 1, 2, and4, computed from the solar energydensity (Desvignes 1991). Theextinctioncoefficientis0.23at550nm.

Figure 2. Photonic response of theJohnson VJ passband compared to theDSLRgreen(G).

Figure3.PhotonicresponseoftheTychoVT passband compared to the DSLRgreen(G).

Wavelength (nm)

S(l

) A.U

.

Wavelength (nm)

S(l

) A.U

.

Wavelength (nm)

F (la

mbd

a)

Wavelength (nm)

Tran

smis

sion

Fac

tor

Figure 6. Johnson’sVjm and DSLR Gmmagnitude deviation, without correction,atairmass1under theJohnson’ssystem.Vjm is normalized at airmass 0.The Gmerrorsare11timesthoseofFigure7.

Figure 7. Tycho VTm and DSLR Gmmagnitude deviation, without correction,atairmass1undertheTychosystem.VTmisnormalizedatairmass0.TheoutliersareMstarsandacoupleofKstars.


Figure 8. e_Vjm magnitude deviation ofthe VJ passband at airmass 0, 1, and 4,under the VJ photometric system. Theresultsshownarethoseofthe110O-to-Kspectraofthelibrary.

Figure9.e_VTmmagnitudedeviationofthe VT passband at airmass 0, 1, and 4,under the VT photometric system. Theresultsshownarethoseofthe110O-to-Kspectraofthelibrary.

Figure10.e_Gtmdeviationof theCSIStransformationoftheGmDSLRchanneltoJohnson’sVjmatairmass1.

Figure11. e_Gcmdeviationof theVSFfilteroftheDSLRagainstJohnson’sVjmatairmass1.

Figure12.e_Gtmdeviationof theCSIStransformationoftheGmDSLRchanneltoJohnson’sVjmatairmass4.

Figure13. e_Gcmdeviationof theVSFfilteroftheDSLRagainstJohnson’sVjmatairmass4.


Figure 15. e_Gcm deviation of the VSFfilteroftheDSLRagainstTychoVTmatairmass1.

Figure 14. e_Gtm deviation of the CSIStransformationof theGmDSLRchanneltoTychoVTmatairmass1.

Figure 16. e_Gtm deviation of theCSIS transformation of the Gm DSLRchannel to Tycho VTm at airmass 4.OutliersarefewKstars.

Figure 17. e_Gcm deviation of the VSFfilteroftheDSLRagainstTychoVTmat

Figure 18. Response of the synthetic filter for a correction toVJ at airmass 0.Thiscorrespond to the correction of the DSLR alone. The DSLR R and B outputs arecombinedtoGweightedwiththecoefficients“a”and“–b”fromTable1(a=0.34;b=0.217).Theresultingcentroidsofthetwopassbandskeepwithin1nminthe–0.4~1.8(B3–V )range.Thenegativesectionintheblueprovidesacompensationoftheresidualexcessoftheblueroll-offoftheVSF.Itworkslikeacomplementarytransformation.

Benn, JAAVSO Volume 40, 2012852

Algorithms + Observations = VStar

David Benn73 Second Avenue, Klemzig, South Australia; [email protected]

Received May 15, 2012; accepted June 25, 2012

Abstract vstar is a multi-platform, free, open source application forvisualizing and analyzing time-series data. It is primarily intended for usewithvariablestarobservations,permittinglightcurvesandphaseplots tobecreated,viewedintabularform,andfiltered.Periodsearchandmodelcreationaresupported.Wavelet-basedtime-frequencyanalysispermitschangeinperiodovertimetobeinvestigated.DatacanbeloadedfromtheAAVSOInternationalDatabaseorfilesofvariousformats.vstar’sfeaturesetcanbeexpandedviaplug-ins,forexample,toreadKeplermissiondata.Thisarticleexploresvstar’sbeginningsfromaconversationwithArneHendenin2008toitsdevelopmentsince2009inthecontextoftheAAVSO’sCitizenSkyProject.Scienceexamplesareprovidedandanticipatedfuturedirectionsareoutlined.

1. Introduction

AconversationwithAAVSODirectorArneHendonat the23rdNationalAustralian Convention ofAmateurAstronomers (NACAA ) in 2008 plantedtheseedforasuccessortoGrantFoster’sdos-basedvstarprogram(Figure1),initiallycreatedforusewiththeAAVSO’sHands-on Astrophysicseducationalmaterial, later renamed Variable Star Astronomy. The motivation for theauthorwassimple: theopportunity todevelopaneasy touse,powerfuldatavisualizationandanalysistoolthatamateurandprofessionalastronomerswouldwanttouse. CorrespondenceoverthenextyearculminatedinAAVSOstaff(includingAaronPrice,ArneHenden,andSaraBeck)comingupwithaninitialspecificationforanewJava-basedmulti-platform(windows, mac os x, linux, opensolaris)implementationofvstar.RegularcommunicationwithSaraBeckcommencedinMay2009.Sincethen,vstardevelopmenthasconsumedmostoftheauthor’ssparetime,familyandothercommitmentspermitting,andbroughtagroupofpassionatepeopletogether.

2. Feature overview

Fundamentally, vstar’s purpose is to permit time series data (ostensiblyvariablestarobservations)fromavarietyofsourcestobeloadedandanalyzed.The initial specification called for data to be loaded from the AAVSOInternational Database (AID), files conforming to the AAVSO Download

Benn, JAAVSO Volume 40, 2012 853

File format, and a simple subset of the latter for personal observations (JD,magnitude,andoptionally:error,observercode,andvalidationflag). Apartfromlightcurveandphaseplotcreation,theloadeddatasetcanbeviewed and searched in tabular form.Selectionof anobservationon a lightcurveorphaseplotissynchronizedwithobservationtablerowselection,andthereverseisalsotrue.ListsoffavoriteAIDobjectscanbecreated.Discrepantobservationscanbeexcludedand/orreportedtoAAVSOHeadquarters. Observationbandscanbedisplayedorhiddenthroughaplotcontroldialog,whichalsoaffectswhatisseenbydefaultintheobservationtable.Simplefilterscanbedefinedtoyieldanewseriesforanalysisandtheobservationtablecanbe searchedusing regular expressions.SeeFigures2 and3 for examplesofdifferent views. Plots can be zoomed and panned.The usual print and savefunctionsareprovided. Binnedmeanscanbecreatedfortherawlightcurveorphaseddata.Errorbarsformeansandobservationscanoptionallybedisplayed.Aninformationwindow shows a breakdown of the loaded dataset by band and a “signalsignificance”statistic in theformofANOVAfor thebandthat is thecurrentsourceforbinnedmeans. Theotherbroadcategoryoffunctionalityisanalysis.Thefirstsub-categoryisperiodanalysis.Invstar,thisisanimplementationoftheDateCompensatedDiscreteFourierTransform(DCDFT)algorithm(Ferraz-Mello1981),yieldingapowerspectrumandtableof“top-hits”foraspecifiedseries, frequencyorperiodrange,andresolution. From within the DCDFT result window, a phase plot can be created. Inaddition,oneormoreperiodseachwithoneormoreharmonicscanbeselectedto create a model.A model’s Fourier coefficients can be viewed along withrelativeamplitudesandphases.Multipleperiodscanoptionallyberefinedviathe CLEANest (Foster 1995) algorithm.When a model is created, it is alsosubtracted from the series on which the DCDFT was performed to yield asecond,“residuals,”series.DCDFTcan thenbeapplied to theseresiduals tolookforfurthersignals(periods),aprocessoftencalled“pre-whitening.”SeeFigure8forasampleDCDFTpowerspectrumandphaseplotresultingfromatop-hitselection. Thesecondmajoranalysiscapabilityistime-frequencyanalysisintheformoftheWeightedWaveletZ-Transform(WWZ;Foster1996).Theuserspecifiesaseries,periodorfrequencyrange,andresolution,andananalysisofchangeinperiodovertimeistheresult.Thiscanbeviewedasa2Dgraph,acontourplot,arotatable3Dgraph,orintabularform.Periodscanbeselectedforphaseplotcreation.Figure4showsperiodchangeforTUMibetween1913and2009.HerethecolorrepresentstheWWZstatistic,thestrengthofaperiodicity,ataparticulartime.ThisexampleisdiscussedinFoster(2010). Anotherkindofmodelthatcanbecreatedisapolynomialfit,alongwiththecorresponding residuals series (forexample, for finding theminimumor


maximummagnitudeinacycleofaMiradataset).Figure5showsapolynomialfit of degree7 foroCet in the JD range2451460 to2451560alongwith a5-daybinnedmeansseries.Thecross-hairsareonthehighestpointofthecurve,atamagnitudeofaround3.315andaJDofaround2451492.8.ThisexampleisbasedupononefoundinFoster(2010). vstar’sin-builtfeaturesetcanbeenhancedbycreatingplug-ins(injava).Thiswill be elaboratedon in another section.Thebeginningsof a scriptingcapabilityexist,permittingcertainoperationstobeautomated.

3. Early development

The original specification led to an initial round of questions. A keydecisionearlyonwas tomovethecontentfromaworddocument toaWiki(initially hosted byAAVSO).This facilitated a dialogue between the authorandtheAAVSOthroughSaraBeck,resultingintheWikibeingannotatedwithquestions and answers. By the end of May 2009, a set of requirements wascreatedthatdeterminedwhatwouldbedevelopedduringphaseone. ItwasdecidedthattheprojectwouldbehostedonSourceForge.AAVSOstaffmemberRichardKinnehelpedestablishthisandarguedthatvstarshouldbelicensedundertheAfferoGNUPublicLicense,aweb-deployment-friendlyversionofthenormalGNUPublicLicense.FeedbackonearlyuserinterfaceprototypeswassoughtfromAAVSOstaffmembers. Itwasrewardingtoreachthepointatwhichvstarcouldbeusedtoloadadataset(fordCep)andcreateaphaseplot.Althoughasimplefeature,itwasatthispointthattheauthorbegantoglimpsehowpowerfulatoollikethiscouldbe.

4. Citizen Sky team

LeadinguptothefirstCitizenSkyworkshopin2009,thevstarSoftwareDevelopment team became the first Citizen Sky project, facilitated byRebeccaTurner. In July 2009, Michael Umbricht, an astronomer at Brown University’sLadd Observatory, contacted the author through Citizen Sky to say that hewanted tohelpon theproject as a tester.After about threemonthsof initialdevelopment,Michael’sdomainknowledgeandearlyfeedbackontheproto-vstarwasvaluable.Leadinguptothefirstworkshopandforquiteafewmonthsthereafter,Michaelplayedakeyroleintesting,promotingvstar,andtriallingitinaclassroomsetting. Soonafterthefirstworkshop(aroundSeptember2009)AdamWeberjoined.He and the author had worthwhile design and implementation discussions.Adamcontributedanumberofbugfixesandhelpedtoimprovethelookandfeelofvstar,especiallyundermac os x. NicoCamargo,ayoungartistlivinginChicago,attendedthefirstCitizen


Skyworkshopandwecorrespondedafterward.Hehasplayedanimportantroleinimprovingvstar’sappearancebycreatingtoolbarbuttonanddesktopicons.Hiswillingnesstohelp,oftenatshortnotice,hasbeenmuchappreciated. Overthelifetimeoftheprojectnumerouspeoplehaveexpressedinterestin contributing. Following through was not always possible due to othercommitmentsorbecausethetimeandeffortrequiredtolearnenoughabouttheexistingcodebasetomakeacontributionwasprohibitive.Manywhodidnotdirectlycontribute todevelopmentor testoften stillprovidedsuggestionsorencouragement.TheCitizenSkyvstardevelopmentteamforumcapturestheteam’sinteractions.Testinganddocumentationarenotespeciallypopularanditwasnotgenerallyeasytointerestpeopleintheseactivities.Astheteamsizegrew,communicationoverheadsrose,withlesstimeavailabletotheauthorforsoftwaredevelopment,comparedwiththefreneticpaceofthefirstfewmonths.Overheadsreducedastheteamstabilized. Themostimportantaspectoftheteamwastheconfluenceofdiverseskills,knowledge,andexperience.Asleaddeveloper,theauthorcoulddefertootherswithgreaterdomainexpertiseorartisticskill.CommunicationmediasuchasWiki, instantmessaging,email,andoccasionalcalls largelycompensatedforthedistance across thePacific separating the author frommost of the team.Questions left with Sara and other team members would often be answeredduringtheauthor’snight.AnAASposterpapercoverstheteamaspectinmoredetail(Hendenet al.2010).

5. Workshops and talks

5.1.CitizenSky1 ThefirstCitizenSkyworkshop,heldattheAdlerplanetariuminChicagoinAugust2009,wasanopportunitytoreceiveearlyfeedbackfromabroaderaudienceabouttheearlyimplementationofvstar.FeedbackfromArneHendenandothersledtoimprovementsandbugfixesbeforethefirstinternaldeploymenttotheCitizenSkyvstardevelopmentteamonNovember13,2009.

5.2.NACAA2010workshop TheNationalAustralianConventionofAmateurAstronomers(NACAA)isheldeverytwoyearsandhasalreadybeenmentionedinrelationtoitsroleingettingvstarstartedin2008.Twoyearslatertheauthorranafull-dayworkshopatthe24thNACAA.Version2.0wasreleasedandannouncedontheAAVSOwebsiteinconjunctionwiththatevent. Feedback from Australian and New Zealand amateurs and members ofVariableStarsSouth (VSS) led to severalnewSourceForge tracker items. Italsoreinforcedtotheauthorcertainuserinterfacechangesthatwouldimprovetheenduserexperience,primarilybyincreasingtheamountofrealestateforplotsandtablesinthemainwindowandmovingsecondaryfunctionstodialogs(seeFigures6and7).


5.3.CitizenSky2 At the secondCitizenSkyworkshop,heldat theCaliforniaAcademyofSciences, San Francisco, in September 2010, the author gave a presentationshowing how vstar could be used to carry out period analysis, minimaidentification with a polynomial fit, and an overview of other capabilitiesaddedsince2009.Again,theresultingfeedbackwasimportantforimprovingthetool. Leadinguptothisworkshop,AaronPricecreatedthe“5StarTutorial”fordataanalysis,acompaniontotheCitizenSky“10StarTutorial,”forobservationofvariablestars.The5StarTutorialshowedhowtousevstartocreateabinnedmeansseries,carryoutperiodsearchwithDCDFT,andcreatephaseplots. Heinz Bernd-Eggenstein was present at the workshop and showed theauthorabuginwhichvstarmisbehavedwithnumericinputinthepresenceofaGermanlocalebeingsetonthehostoperatingsystem.Fixingthisseeminglysimple problem took some weeks after the workshop. Additional localeimprovements are on the roadmap, such as providing language specific (forexample,German,Spanish,andPortuguese)versionsofvstar.

5.4.NACAA2012update Four years after the initial conversation with Arne Henden, a talk anddemonstrationofprogresssincethe2010fulldayworkshopwasgivenatthe2ndVariableStarsSouthColloquiumheldinconjunctionwiththe25thNACAAinBrisbane. TimespentduringbreakswithVSSmembers,inparticularMarkBlackford,DavidMoriarty,AlanPlummer,andTomRichards,wasbeneficialaswetalkedabouttheiruseofvstar.Forexample,theneedforanASASdatasourceplug-inwasexpressed.

6. From fortran to java

Evenbeforedevelopmentofvstarhadbegun,MatthewTempletonpointedtheauthortoapaperabouttheDCDFTalgorithm(Ferraz-Mello1981).GrantFosterhadpreviouslywrittenanimplementationofDCDFTinbasicwhichwassubsequentlyconvertedtoafortranversionbyMatthewaspartofAAVSO’sTSconsole-basedprogram. When the time came to implement DCDFT for vstar, there were a fewchoices:

• ImplementDCDFTpurelybaseduponthepublishedliterature.

• Convert the fortran ts code to java. The author experimented withfortrantojavatranslators,butatthetime,nonewasfoundtobewithoutimportantbugs.


• Convert the fortran TS code to c and call from vstar as “nativemethods.”

• Convertthefortran tscodetocandthentojava.

fortran toc translatorsexist, inparticularf2c.Thiswasmadeuseof inordertobeabletosource-leveldebugthetscodeincformwhenpossiblebugsinthefortrancodewerefound.Thecodegeneratedbysuchtranslatorstendstobecrypticandhavedependenciesuponspeciallibraries.Callingccodethroughjava’s native interface mechanism would have required natively compiledlibrariesforeachoperatingsystem,somewhatantitheticaltovstar’sgenerallyplatform-independentimplementation. Otherthanthis,therearesufficientincompatibilitiesbetweentheconsoleandtextmenudrivennatureanddatastructuresofthetsprogramcomparedwithvstar’sinternalsanduserinterface,thatintheend,amixtureofthefirstandsecondoptionswasemployed. First,theappropriateliteraturewasreadtogetanunderstandingofDCDFT(Ferraz-Mello 1981). Next, a perl script was written to perform a partialtranslationof thets fortrancode into java.Next,each lineofemitted javacodewas inspected for logicalequivalencewith the fortran code.Thecorealgorithmswere translatedandextracted in thiswayandexposed to the restof vstar through the appropriate menu items and dialog boxes. For testingpurposes, ts was treated as a reference implementation for DCDFT. Unittestswerewrittenfor the java implementationof thealgorithmandchecked(automatically,aftersomeinitialmanualchecking)againsttheresultsgeneratedbyts for thesame input.Thesamestrategywasused to implementand test wwzinvstar. There is a difference in emphasis between implementing and testingalgorithmsfromapublicationsuchasMeeus(1991)—whichwasusedforJDcalculationsinvstar—anddoingsofromtheliterature.ThepurposeofabooksuchasMeeusistounambiguouslydescribeanalgorithmandprovideatleastminimaltestcases.Apaperthatdescribesanalgorithmdoesnothavequitethesame obligation. Hence the approach of using “battled-tested” fortran as areferenceimplementationandsemi-automatedtranslationasopposedtowritingfromscratchfromtheliterature,whilemakinguseofittobolsterunderstandingofthealgorithm.Intheend,thekeybenefitisthatthepowerfulfunctionalityofthefortran tsand wwzcodehasbeenmadeavailableinvstar,andalongtheway,somebugswereuncoveredintheoriginalfortrancode.

7. Plug-ins

vstarplug-inscanbecreatedusingthejavaprogramminglanguage(orinfact,anylanguagethatcanbecompiledtojavavirtual machineclassfiles)inorderto:


• Loadobservationsfromanarbitrarysource.

• Performacustomdatasetfilteringoperation.

• Implementanewperiodanalysisalgorithm.

• Carryoutanarbitraryoperationontheloadeddataset.

• Createageneralpurposetool.

• Implementamodelcreationtool.

Perhapsnottoosurprisingisthatobservationsourceplug-inshavesofarbeenthemostcommonlywrittenorrequested,sincethismakesitpossibletoloaddatasetsfrommorediversesourcesthanthosedefinedbytheAAVSO. Todate,observationsourceplug-inshavebeenwrittenforKeplermissionpublicdatareleaseFITSfilesandSuperWASPsurveyFITSfiles.BothofthesewerewrittenincollaborationwithDougWelch.OtheruserssuchasKenMogulandAlanPlummerpromptedthedevelopmentofanAAVSOsimpleandextendeduploadfileformatobservationsourceplug-in.Thisformatcanbehand-craftedor generated by an application such as vphot for use in uploading multipleobservationstotheAAVSOInternationalDatabase.Someplug-ins,ifcommonlyusedlikethisone,mayeventuallybeaddedintothecoreofvstar’scodebase. Anexampleofthesecondcategorywasaplug-inwrittenbySaraBecktoshowwhichobservationsina loadeddatasetweremadebyobservers in,forexample,Ireland. Asfarastheauthorisaware,noperiodanalysisplug-inshavebeenwrittenyet,buttwocandidatesareAoV(Schwarzenberg-Czerny1989)andFastChi-squared(Palmer2009).Internally,DCDFTandWWZaretreatedasplug-ins,implementingtherequiredinterfaces,theonlydifferencebeingthattheyarenotdynamicallyloadedwhenvstarstarts. Anexampleof the“arbitraryoperation”plug-in typewascreatedby theauthor when AAVSO member Mike Simonsen expressed a need to selectdatapoints on a light curve plot to determine mean time between selectedobservations (along with mean magnitude).An example of the last plug-incategoryisaJDtocalendardatecalculator.Thevstarplug-inlibrary(http://www.aavso.org/vstar-plugin-library) and the vstar webpage (http://www.aavso.org/v-star-overview)canbeconsultedformoreinformation.

8. Deployment

java webstart™isthedeploymentmechanismusedwhenlaunchingvstarfromtheAAVSOwebpageandremainstheeasiestwaytobeginusingvstar.webstart™imposes“securityconstraints”similar to that imposedbya javaapplet.Ittooksometimetomakevstarworkproperlywithintheseconstraints,especiallyinthepresenceofdynamicallyloadedplug-ins.


For each formal release, there were one or more testing releases madeavailable to the Citizen Sky team through webstart™. Each formal releasehasbeenaccompaniedbyadownloadablearchive(fromSourceForge)thatcanbeunzippedandrunasanormallocalapplication.Morerecently,operating-systemspecificlauncherprograms/scriptswereaddedtoimprovethelocalrun-timeexperience,inparticularbymakingstart-upmemoryallocationequivalenttothewebstart™deploymentandbyaddingadesktopiconfordos/windowsandmac os x.

9. Science examples

ThissectiongivesbriefexamplesofhowvstarhasbeenusedforCitizenScience.Theseexamplesarenotexhaustive,buttheyarerepresentative.

9.1.Cepheididentification Inanexampleofprofessional-amateurcollaboration,amateurastronomerKen Mogul has partnered with Doug Welch, a professional astronomer atMcMasterUniversity,onalong-termprojectusingtherobotictelescopenetworkAAVSOnettoobtainhigh-qualityphotometrictimeseriesofType2CepheidsinSloangrizfilters.Ambiguouslyclassifiedvariables(CEP,CEP:)werealsoincludedtoensurethattheirclassificationscouldbeimproved(Welch2012).vphot is used to process images and vstar is used to help eliminate targetsthatdon’tmeettheprojectcriteria.InKen’swords:“Ihavealsobeenabletodataminethedatafornewvariablesoutsidethegoaloftheproject.vstarhasenabledmetomakeintelligentsuggestionstotheprofessionalonwhattolookatandwhattodismisstherebysavingtheprofessionaltimetofocusonthebigpicture”(Mogul2012). By using vphot and vstar together, Ken was easily and quickly able tofirstreducethedataforeveryotherstar,apartfromtheoriginaltarget,inthefield-of-view being studied, to look for possible variability. Then vstar’sDCDFT and phase plot features (see Figure 8) enabled him to immediatelyphasethedataintoaclassification-revealinglightcurve,suchasintheexampleinFigure8ofstar2MASSJ03145502+5618172(Mogul2012).KenwasalsoabletoreclassifyGVAurasaClassicalCepheidasshowninFigure9. Again, inKen’swords:“Eventuallywithenoughdata,vstarwillenablemetobeatthecenteroftheactionconceptually,withoutmyhavingtospendagreatefforttolearnandunderstandthingslikeIRAF.Thesetoolsareashiningexampleofhowtomakecitizenscienceaviableforcegoingforward.AAVSOnet,vstarandvphothaveenabledme,withnoequipment…togofromobservingtoorganizingtoanalyzinganddrawingusefulconclusions…withonlyacomputerandInternetconnection…apossibilitywhichwasalmostunimaginableevenadecadeago,excepttotheveryfarsighted”(Mogul2012).


9.2.Keplerdatamining Using vstar’s Kepler data source plug-in and DCDFT and phase plots,KevinAltonhasexploredeclipsingvariablestarsystemsobservedbytheKeplerspacecraft,lookingforchangesinminima/maximaacrosscycles.AccordingtoKevin,thisisapreludetopotentiallymappingmagneticactivitycyclesand/orstarspotmigrationinselectedcontactbinaries(Alton2012).

9.3.LongtermeAurigaelightcurve BrianKloppenborghasusedvstar’sWWZfeaturetolookforchangingormultipleperiods ineAur’s long-termphotometricarchive lightcurve.Briancommented that nothing has been found so far, as others before him havediscovered (Kloppenborg 2012). Brian’s use ofWWZ exposed a bug in thefortran and java implementation (in thepresenceof significantgaps in thedata).Thisisnowontheinevitablelistofthingstofix.

9.4.Lightcurvesforillustrationinarticles Articles containing light curves saved from vstar have appeared inAustralian Sky & TelescopebyVSSmemberAlanPlummerandbyothersinVSSnewslettersandelsewhere.

9.5.MiraFouriercoefficientteam(CitizenSky) ApartfromactingasatestinggroundforDCDFT,Fourierseriesmodelling,andWWZinvstar,theCitizenSkyMiraFouriercoefficientteamneededtobulk-downloadaround400MiradatasetsoffixeddurationfromtheAID.vstarcanbescripted(onlythroughjavascriptcurrently)toautomatesomeoperations,suchasdatafileorAIDdatasetloading.ThisfeaturewasusedtobulkdownloadtheseMiraobservationdatasets.

9.6.Periodsearchandphaseplots Aspartoflearningaboutvariablestarphotometryandanalysisinhisworkon the SPADES project (Richards 2012), VSS member David Moriarty hascarried out period search with vstar on photometric data obtained for thecontacteclipsingbinarysystemTWCruandcomparedittoperiodandepochvaluesfoundinGCVS,Dvorak,andKrakowrepositories.

10. Future directions

Althoughstillunderactivedevelopment,vstarisalreadyprovingtobeausefultoolforactivitiesrangingfromsimplyexploringlightcurvesinAIDtoanalyzingphotometricdatasoastodetermineastar’speriod.Theinitialgoalforvstarwastocreateafree,easy-to-usetoolforbasicvariablestarobservationvisualizationandanalysis.Useranecdotessuggestthatthishasbeenachieved. Muchhasbeendone,butthereisstillplentytodo.Whatfollowsgivessomeindicationofvstar’sfuture:


• ParallelizationofDCDFTandWWZtomakeuseofmulti-coremachineswithconcurrentjavathreadsmappingtocores.

• Memory footprint reduction.Forexample,eachobservationdata-pointis represented by an object that consumes more memory than it should.Addressingthiswillpermitlargerdatasetstobeloaded.

• Betterdocumentation, in the formof ausermanual asopposed to thecurrentminimalHelpmenuitemandoccasionalarticles.

• More analysis features, for example: time of minimum/maximum, forexample,foreclipsingbinaryepochdetermination;alternativestoDCDFT,suchasAoVandFastChi-Squared.Thesecanalsobedevelopedbyothersasplug-ins;O–Canalysis;Lowessfit,forexample,forminimadetermination(Foster2010).

• AAVSO download files can be generated as lines of comma-, tab-, orspace-separatedvalues.Unlessvaluesarequoted,ambiguityispossible(forexample,commasincommentsfields).Thishasbeenflaggedasanissueandwillbepursuedsincesomefilescontainlinesthatcannotbeunambiguouslyparsedbyvstar(oranytool),somustbeomittedatloadtimeandreportedaserroneoustotheuser.

• Permittogglingbetweenmagnitudeandfluxvaluesforparticularkindsofanalysis.

• Makeplug-ininstallationandmanagementalessmanualprocess.

• Improvethequalityofplotsforpublication.

• Localization(forexample,Spanish,German,Portuguese,orPersian).

• Increasing the power of models, for example: addition of arbitraryterms,suchasforobserverbias(aspermittedbyTS);makingiteasiertoaccumulateperiodsthroughouttheprocessofpre-whiteningforsubsequentmodelcreation;mergingtwoormoreexistingmodels;modelcreationfromWWZ.

• Althoughplug-inscanbecreatedtoperformarbitraryfilteringoperations,the current in-built filtering capability is limited to the equivalent of anexpression language over a subset of an observation’s fields, supportingconjunction (logicalAND), relational operations (>, <, =, <=, >=), andnegation. This could be made more powerful by permitting expressionscontainingdisjunctions(logicalOR)andallowingallobservationfieldstobeused.

• The scripting API should grow to permit more operations to beautomated.


• ReplacementofdirectAIDdatabaseaccesswithawebservice.ThiswouldalsoopenupprogrammaticaccesstoAIDtoabroaderrangeofapplicationsanddevices,butthisissomethingthatcannotbedoneinisolationandisadecisionforAAVSOsinceithasinfrastructureimplications.

• Otherdatasourceplug-ins,suchasforASAS.

• Bugfixes!SeetheSourceForgetrackerforthese,theissuesabove,andothersbesides(https://sourceforge.net/projects/vstar).

• Ingeneral,theSourceForgetrackerandchangelog(updatedeachrelease)willcontinuetodocumenttheprocessofchange.


TheauthorwouldliketothankArneHendenandAaronPriceforgettingitallstartedandforongoingencouragement;andSaraBeckformentoring,beingan AAVSO liason, and providing regular support and enthusiasm. RebeccaTurnerhasbeensupportiveasCitizenSkyprojectmanager.DocKinneprovidedsystemadministrationsupport,helpedestablish theSourceForgeprojectsite,andsortoutlicenseissues.MatthewTempletonpatientlyansweredquestionsaboutalgorithms.Allprovidedencouragement. MichaelUmbricht,AdamWeber,NicoCamargo,HeinzBernd-Eggenstein,Jaime Garcia, Doug Welch, Ken Mogul, and Mike Simonsen—vstar teammembersandusers—providedfeedback,assistance,testing,andencouragement.ThanksalsotoGrantFosterforwritinghislightcurveanalysisbook(Foster2010), introducingme to theR statistical analysis language, and for helpfultechnicaldiscussions.Thesepeoplehavegivengenerouslyof their timeandtalentsinresponsetomyquestions. Members of VSS have also provided encouragement, advice for futuredirections,andbetterstill,havemadeuseofitintheirresearch(forexample,MarkBlackfordandDavidMoriarty). Alittlemorethantwoyearsafterthevstarprojectstarted,IreceivedemailfromArneHendentosaythatIwastherecipientofthe2011AAVSODirector’sAward.Considering theprevious recipientsof thisaward, Iamhonoredandhumbledtohavereceivedthis.Membersofthevstarteam,andothers,helpedtomakethispossible. MysupportivewifeKarenandchildrenNicholasandHeatherhavebecomevery tolerantof theirhusband’s/father’snocturnalnature,especiallyover thelastfewyears.Nicholasalsohelpedwiththedos/windowslauncher. The author greatly appreciates the opportunity to develop vstar, toparticipate in the Citizen Sky andAAVSO communities, and to attend bothCitizenSkyworkshops. Thetitleforthispaperwasinspiredbya1976bookbycomputerscientistNiklausWirth—Algorithms + Data Structures = Programs.


OnbehalfoftheAAVSOandtheCitizenSkyProject,theauthoralsogratefullyacknowledgesgrant000379097fromtheNationalScienceFoundation.

References

Alton,K.2012,privatecommunication.Ferraz-Mello,S.1981,Astron. J.,86,619.Foster,G.1995,Astron. J.,109,no4,1889.Foster,G.1996,Astron. J.,111,1,555.Foster,G.2010,Analyzing Light Curves, a Practical Guide(http://www.lulu.

com/shop/grant-foster/analyzing-light-curves-a-practical-guide/paperback/product-11037112.html).

Henden,A.,Benn,D.,Beck,S.,Price,A., andTurner,R. 2010,Bull. Amer. Astron. Soc.,42,510.

Kloppenborg,B.2012,privatecommunication.Meeus,J.1991,Astronomical Algorithms,Willmann-Bell,Richmond,VA.Mogul,K.2012,privatecommunication.Palmer,D.M.2009,Astrophys. J.,695,496.Richards,T.2012,“SearchforPlanetsAroundDetachedEclipsingSystems,”

(SPADES; http://www.variablestarssouth.org/index.php?option=com_content&view=article&id=59&Itemid=49).

Schwarzenberg-Czerny,A.1989,Mon. Not. Roy. Astron. Soc.,241,153.Welch,D.2012,privatecommunication.

Figure1.GrantFoster’soriginaldos-basedvstar(providedbyAAVSO).


Figure2.AplotofhCar,anobservationselectedinthecross-hairs,andadetaildialog.

Figure3.ThetabularviewofthehCardatasetshowninFigure2withthesameobservationrowselected.

Figure4.WWZplotforTUMishowingperiodchangeoveralmostacentury.


Figure5.Apolynomialfitofdegree7foroCetwith5-daybinnedmeans.

Figure6.Ascreen-shotofvstaratthetimeofNACAA2010.

Figure7.vstar’smodifiedinterfaceasithasbecomesinceNACAA2010.


Figure8.AvstarDCDFTpowerspectrum(upperpanel)andphaseplot(lowerpanel)resultingfromtop-hitperiod,for2MASJ03145502+5618172.

Figure9.PhaseplotforGVAurresultingfromDCDFTperiodanalysis.

Camargo, JAAVSO Volume 40, 2012 867

An Artist’s Note on Art in Science

Nico Camargo4233 N. Hermitage Avenue, #3A, Chicago, IL 60613; [email protected]

Received May 14, 2012; revised October 22, 2012

Abstract Idecidedtowriteaboutartinsciencebytellingpersonalanecdotessurroundingmyinvolvementinastronomy.Theseportraywhatdroveme(withacareerintheFineArts) totryscientificillustrationthroughinvolvementintheAmericanAssociationofVariableStarObservers’CitizenSkyproject toobservetheeclipseofeAurigae.TheseaccountsdefinewhatIbelievetobeatthecoreofbeingascientificillustrator:theimportanceofmaintainingaccuracyand factual detail without compromising the compelling visuals that evokecuriosity.This,asmostpeoplerealize,isanimportantfactorinbeingabletosuccessfullyengagethepublicinscience—particularlyinastronomy.However,myintentionintellingtheseanecdotesgoesdeeperthanstatingtheimportanceof disseminating scientific knowledge through imagery—for which ampleexamplesandliteraturealreadyexist.Instead,I’mreallyaftercontrastingtheroleofascienceillustratorversusthatofanartist.Indoingso,IwillunderscorewhatIbelieveillustratingphenomenainsciencereallyisallabout.ThisnoteisnotintendedasascholarlytreatisebutratherpersonalreflectionsrelativetomyinvolvementinCitizenSky.

1. My introduction to astronomy

Ononesummermorningin2009,whileIwaspreparingtobeginapainting,IplayedadailypodcastIsometimeslistenedto,called365DaysofAstronomy.Thatday,awelcomingvoicewassayingsomethingaboutanorganizationcalledCitizenSky.Sheproceededtodescribewhatwasknown,atthattime,aboutapeculiarstarsystemintheconstellationofAuriga,whichhadbeenshroudedinmysteryforhundredsofyears.Then,shewentontoexplainthatthiscelestialspeck,dubbedeAurigae,wouldbevisiblebytheunaidedeye(evenundercitylights),andmostinterestinglywouldbeundergoinganeclipselastingabouttwoyears.Becausethiseventonlyhappenseverytwenty-sevenyears,sheurgedthepublictoassistherorganizationbycollaboratinginanyrelevantwaytoachieveitsmission—tofindoutmoreaboutthisstar’sstrangedisc-likecompanionasittransitsacrosssaidstar.AsIbecameintriguedwiththisweirdeclipsingbinarysystem,thenarratormentionedthatCitizenSkywouldbehavingaworkshopattheAdlerPlanetariuminChicago(justacoupleofmilesfromwhereIlived),andcalledonthosewhowishedtolearnmoreabouteAurtohelptheastronomycommunityunderstandthisrarephenomenon.Imarkedmycalendar,andwhenthedatecame,Ieagerlyjumpedonthetraineachmorningforwhatwouldbea

Camargo, JAAVSO Volume 40, 2012868

funweekendoflecturesandconversationswithpassionate,brightindividualstrying to set up anunprecedented campaignof observationsduring thenext640–730daysofeclipse. My enthusiasm for astronomy was entrenched in curiosity about howtheuniverseworks.VeryearlyrecollectionsofCarlSagan’sCosmosandtheSTS Challenger disaster on television are embedded in my memory to thisdayandhadimpactedthewayIviewscience.Particularlyspaceexplorationintrigued me—from the standpoint of human achievement and engineeringadvancement—becauseitwasacommontopicatthedinnertablegrowingup.Thatfamousimageofanastronautwearingajet-pack,floatingaloneinspaceaboveEarth,wasinmygrandfather’shomeoffice,andalate1980stelevisionmini-seriesabouttheApollomissionscementedmyutmostadmiration,wonder,andthirstforlearningaboutspaceandtheuniverse.Whatallofthesememorieshave in common is awe-inspiring imagery.Whether on television or in stillpictures, these images, aswell asmanyothers (certainly some fromsciencefictionmoviesaswell)wouldstirmycuriositytolearnaboutwhatisbeyondourhome. BackinChicagoattheAdlerPlanetarium,Iwassoakinginalltheinformationavailable about eAur: light curves from past observation campaigns, crudeillustrations,dataanalyses;that,andmuchmoreinformation,providedseveralpossibilitiestoillustratewhatwaspresumedtobeaneclipsingbinarysystemthatwasjusttoofartobecapturedinphotographicformat—notevenwithourmost powerful observatories.What eAur was remained a mystery awaitingresolution,andtome,thismeantanopportunitytoinspireotherswithmyownspace images—ones that would tell what would otherwise be a difficult-to-comprehendcelestialconundrum.Imetthepodcast’svoice,RebeccaTurner,andtherestofCitizenSkycrewthatweekendandfromthatpointon,Iwascommittedtoprovidingthemwithillustrationsthatwouldhelptosupporttheirmission.

2. Nature has better imagination

In 2010 Citizen Sky met again, that time in San Francisco, to discussprogress on eAur’s eclipse and analyses of new data.After lectures, onceagain,IengagedinconversationswithheadastronomersandexpertsoneAurtofindoutwhatthenewleadinghypothesesworthillustratingwere.Iwantedtodepictexactlywhat theyenvisioned,ormoreappropriately,what thenewinformationwastellingthem.About2,000light-yearsaway,theonlywaytobringthiseclipsingbinarysystemtolifeisbyimaginingandillustratingit,andeverynewpieceofthepuzzlemeantthatwecouldhaveamoreconcreteideaof the system’s objects. Evidence of the system’s objects’ approximate size,positioning,molecularcomposition,andshapealreadycreatedanexactmodelofhoweAurcouldlook,however,therewerenewdetailsthatdismissedearlierhypotheses.

Camargo, JAAVSO Volume 40, 2012 869

When I began illustrating e Aur, I looked at earlier illustrations of thesystem,aswellasonesofothersimilarsystems.Onehadablackholewithspewing jets of energy coming from the middle of this companion disk—acompelling image that was negated by data confirming that there were noblackholesineAur.(That’snottosaythatimpressivejetsofenergyspewingfromblackholesdon’texist,orhaven’tbeenseen—theyhave.)AnothereAurillustrationhaditsvisiblestar(whatcametoberecognizedasalargeF-typestar)pullingmassfromtheobscurecompanionthroughtheinnerLagrangianpointandcreatingadiskofmaterialifitsown—thatideawasalsorejectedaftermoresoliddatacametolight.Again,traffickingmaterialbetweentwocelestialobjectsthattrespasstheirRocheLobedoesexist.Mypointisthatatthetime,itwasanybody’sguesswhatwasgoingonineAur,butasmoreknowledgewasacquired,theseguesseswereappropriatelymarginalized.Iwassupposedtoillustratethenew“guesses,”anditwasmydutytomakeanattractiveimagewhilekeepinginmindthatanyextrapolationofmyownwouldwronglymaketheillustrationbecomesomethingotherthaneAurigae—justliketheonespriortomine,justlikemyfirstones. Today, my favorite eclipsing binary system remains much of a mysterydespitehard-earnednewdata.Itsdark,humongousdisc-likecomponentcouldbe a planetary system in its infancy, or one in limbo that will never formplanets due to gravitational pulls from its inside (where a small B star wasfound)andtheF-starcompanion.eAurcouldendupbeingseveralsurprisingthings(butnot toomany).However, theseplausiblesurprises, I’msure,willbefascinating.Naturehasawayofrevealingherself,inthemost“out-there”ofways—sheoutdoesevensciencefictionflicks.Fromplanetswithfourstars,to planetary formation itself, we should just illustrate natural phenomena ashonestlyaspossible,sincethoseimagesarecertainlyas(ifnotmore)creativeandimaginativethananyartistcouldimagine.

3. Artwork created in support of Citizen Sky and the AAVSO

TheworkIdidrelatedtoCitizenSkyandeAurwasmyfirstinscientificillustrationandmyfirstrelatedtoastronomy.ArtworkIcreatedonbehalfofCitizenSkyandtheAAVSOincluded:

•potentialdesignsfortheCitizenSkylogo•sevendepictionsoftheeAursystem•iconsforthedataplottingandanalysissoftwarevstar,acrucialelementofCitizenSkythatisbeingusedbyvariablestarobserversandanalystsfarbeyondtheoriginalCitizenSkyaudience•illustrationforaCitizenSkyparticipationcertificate•charactersforaCitizenSkycomicstrip

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• illustration commemorating the receipt of the AAVSO’s 20 millionthvariablestarobservation• October page in the American Astronomical Society’s 2011 calendar,commemoratingtheAAVSO’scentennial•potentialdesignsfortheAAVSOlogo

4. Not apples and oranges, more like apples and onions

Asanemergingvisualartist,Iunderwentanintentionalshiftfromnebulousabstractconceptualismtotheconstrictionsofimperativepredestinarianisminpicture-making.Thatshifteffectivelyconvertedmeintoanillustratorforthetimebeing.Thisdualitymustbeaddressedbecause,whilethejuxtapositionofthesetwodifferentfieldshasprovidedanabundanceofintellectandcreativityinmyart,onemustunderstandtheextentsandlimitationsthatthesetwofieldsimpose on each other. To say that a scientific illustrator took some artisticliberties when rendering a natural phenomenon implies misdirection—suchas fabrication of facts, exaggeration, and image entitlement, to name a few.Conversely,whenanartistrendersideasasvisualexplanationsofthemselves,withoutcontextambiguity,orabstractionofanykind, thisartistbecomesanillustrator. There are certain things in the universe that can’t be directly translatedinto visual form, so we use symbols, approximations, and the imagination.But,scientificillustratorsfillinthisgap,andtheymustderivetheirworkfromresearchandscientifichypotheses.Ascientificillustratorhastheobligationtoexplainascientificsubjectconcisely,thoroughly,andaccurately,whetherthemediumisanimationorillustration,andindoingso,heorshemustexcitetheimaginationwithoutmisleadingtheviewer. Beauty and aesthetics are very important aspects of scientific imagery.Undoubtedly, science illustrators must make their subject matters visuallyattractive and unforgettable. That being said, scientific imagery should alsobereserved,humble,andhaveananonymousquality.Itshouldbeeconomicand focused solely on its depictions, without compromising on its scientificaccuracy. Scientific illustrators are not making art; they are not making apersonal statement; they are not trying to convey an idea indirectly or perambiguitiesandinsinuations,noraretheyspeakingaboutthemselves,abstractconcepts (like loveor life),or society. Instead, theyareprovidingaprecise,hyper-realistic representation(asbestas theycan)of thephysicalworldandits natural occurrences. Scientific illustrators have formal and conceptualconstrictionsandareobligedtocapturethesubjectmatterexplicitly.Theartistryinscientificimageryliesinhoweffectiveandwell-executedthesubjectmatteris,inordertomakelearningfaster,easier,andmoreenjoyable. MyhopeisforothercreativeindividualstofollowthepointsIlayoutinthisnote,andtorememberthattheessenceofscientificillustrationliesinthecomprehensionofknowledge.

JAAVSO Volume 40, 2012 871

JAAVSO Volume 40, Number 2—other papers received

Richmond and Smith, JAAVSO Volume 40, 2012872

BVRI Photometry of SN 2011fe in M101

Michael W. RichmondPhysics Department, Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY, 14623; [email protected]

Horace A. SmithDepartment of Physics and Astronomy, Michigan State University, East Lansing, MI 48824; [email protected]

Received March 19, 2012; revised April 4, 2012; accepted April 11, 2012

Abstract We present BVRI photometry of Supernova 2011fe in M101,starting2.9daysaftertheexplosionandending179dayslater.Thelightcurvesandcolorevolution show thatSN2011febelongs to the“normal’’ subsetoftypeIasupernovae,withadeclineparameterDm15(B)=1.21±0.03mag.Aftercorrectingforthesmallamountofextinctioninthelineofsight,andadoptinga distance modulus of (m – M ) = 29.10 mag to M101, we derive absolutemagnitudes MB = –19.21, MV = –19.19, MR = –19.18, and MI = –18.94.WecomparethevoluminousrecordofvisualmeasurementsofthiseventtoourCCDphotometryandfindevidenceforasystematicdifferencewhichdependsoncolor.

1. Introduction

Supernova(SN)2011feinthegalaxyM101(NGC5457)wasdiscoveredbythePalomarTransientFactory(Lawet al.2009;Rauet al.2009)inimagestakenonUT2012Aug24andannouncedlaterthatday(Nugentet al.2011a).AstheclosestandbrightesttypeIaSNsinceSN1972E(Kirshneret al.1973),and moreover as one which appears to suffer relatively little interstellarextinction,thiseventshouldprovideawealthofinformationonthenatureofthermonuclearsupernovae. WepresentherephotometryofSN2011feintheBVRIpassbandsobtainedattwosites,startingonedayafterthediscoveryandcontinuingforaspanof179days.Section2describesourobservationalprocedures,ourreductionoftherawimages,andthemethodsweusedtoextractinstrumentalmagnitudes.Insection3,weexplainhowtheinstrumentalquantitiesweretransformedtothestandardJohnson-Cousinsmagnitudescale.Weillustrate the lightcurvesandcolorcurvesofSN2011feinsection4,commentbrieflyontheirproperties,anddiscussextinctionalongthelineofsight.Insection5,weexaminetherichhistoryofdistancemeasurementstoM101inordertochoosearepresentativevaluewithwhichwethencomputeabsolutemagnitudes.UsingaverylargesetofvisualmeasurementsfromtheAAVSO,wecomparethevisualandCCDV-bandobservationsinsection6.Wepresentourconclusionsinsection7.

Richmond and Smith, JAAVSO Volume 40, 2012 873

2. Observations

This paper contains measurements made at the RIT Observatory, nearRochester, New York, and the Michigan State University (MSU) CampusObservatory, near East Lansing, Michigan. We will describe below theacquisitionandreductionoftheimagesintoinstrumentalmagnitudesfromeachsiteinturn. TheRITObservatoryislocatedonthecampusoftheRochesterInstituteofTechnology,at longitude77:39:53West, latitude+43:04:33North,andanelevationof168metersabovesealevel.ThecitylightsofRochestermakethenortheasternskyespeciallybright,whichattimesaffectedourmeasurementsofSN2011fe.WeusedaMeadeLX200f /1030-cmtelescopeandSBIGST-8E camera, which features a Kodak KAF1600 CCD chip and astronomicalfiltersmade to theBessellprescription;with3×3binning, theplate scale is1.85secondsperpixel.TomeasureSN2011fe,wetookaseriesof60-secondunguidedexposuresthrougheachfilter;thenumberofimagesperfilterrangedfrom10,atearlytimes,to15or20atlatetimes.Wetypicallydiscardedafewimages in each seriesdue to trailing.Weacquireddark and flatfield imageseachnight,switchingfromtwilightskyflatstodomeflatsinlateOctober.ThefilterwheeloftenfailedtoreturntoitsproperlocationintheR-band,so,whennecessary,weshiftedtheR-bandflatsbyasmallamountinonedimensioninordertomatchtheR-bandtargetimages.Wecombined10darkimageseachnighttocreateamasterdarkframe,and10flatfieldimagesineachfiltertocreateamasterflatfieldframe.Afterapplyingthemasterdarkandflatfieldimagesintheusualmanner,weexaminedeachcleanedtargetimagebyeye.WediscardedtrailedandblurryimagesandmeasuredtheFWHMofthoseremaining. TheXVista (TreffersandRichmond1989) routines starsandphotwereused to find stars and to extract their instrumental magnitudes, respectively,usingasyntheticaperturewithradiusslightlylargerthantheFWHM(whichwastypically4"to5").AsFigure1shows,SN2011feliesinaregionrelativelyfreeoflightfromM101(seealsoSupplementaryFigure1ofLiet al.2011).Asacheckthatsimpleaperturephotometrywouldyieldaccurateresults,weexaminedhigh-resolutionHSTimagesofthearea,usingACSWFCdataintheF814Wfilteroriginally takenaspartofproposalGO-9490 (PI:Kuntz).Thebrightesttwosourceswithina5"radiusofthepositionoftheSN,R.A.=14h03m05.733s, Dec, = +54˚ 16' 25.18" (J2000) (Li et al. 2011),haveapparentmagnitudesofmI~_21.8andmI~_22.2.Thus,evenwhentheSNisatitsfaintest,inourfinalI-bandmeasurements,itismorethanonehundredtimesbrighterthannearbystarswhichmightcontaminateourmeasurements. Between August and November 2011, we measured instrumentalmagnitudes from each exposure and applied inhomogeneous ensemblephotometry (Honeycutt 1992) to determine a mean value in each passband.StartinginDecember2011,theSNgrewsofaintintheI-bandthatwecombined


thegoodimagesforeachpassbandusingapixel-by-pixelmedianprocedure,yieldingasingleimagewithlowernoiselevels.Wethenextractedinstrumentalmagnitudesfromthisimageinthemannerdescribedabove.Inordertoverifythatthischangeinproceduredidnotcauseanysystematicshiftintheresults,we also measured magnitudes from the individual exposures, reduced themusingensemblephotometry,andcomparedtheresultstothosemeasuredfromthe median-combined images.As Figure 2 shows, there were no significantsystematicdifferences. The Michigan State University Campus Observatory lies on the MSUcampus,atlongitude05:37:56West,latitude+42:42:23North,andanelevationof 273 meters above sea level. The f /8 60-cm Boller and Chivens reflectorfocuses light on anApogeeAlta U47 camera and its e2V CCD47-10 back-illuminated CCD, yielding a plate scale of 0.56 arcsecond per pixel. FilterscloselyapproximatetheBessellprescription.Exposuretimesrangedbetween30and180seconds.Weacquireddark,bias,andtwilightskyflatfieldframesonmostnights.Onafewnights,highcloudspreventedthetakingoftwilightskyflatfieldexposures,soweusedflatfieldsfromtheprecedingorfollowingnights.TheI-bandimagesshowconsiderablefringingwhichcannotalwaysberemovedperfectly.Weextractedinstrumentalmagnitudesforallstarsusingasyntheticapertureofradius5.4seconds.

3. Photometric calibration

In order to transform our instrumental measurements into magnitudesin the standard Johnson-Cousins BVRI system, we used a set of localcomparisonstars.TheAAVSOkindlysuppliedmeasurementsforstarsinthefieldofM101(Henden2012)basedondatafromtheK35telescopeatSonoitaResearchObservatory(Simonsen2011).WelistthesemagnitudesinTable1;notethattheyareslightlydifferentfromthevaluesintheAAVSO’son-linesequenceswhichappeared in late2011.Figure1shows the locationof thethreecomparisonstars. TheAAVSOcalibrationdataincludedmanyotherstarsintheregionnearM101.Inordertocheckforsystematicerrors,wecomparedtheAAVSOdatatophotoelectricBVmeasurementsinSandageandTammann(1974).ForthefivestarslistedasA,B,C,D,andGinSandageandTammann(1974),whichrange 12.01 <V < 16.22, we find mean differences of –0.013 ± 0.038 maginB-band,and–0.009±0.022maginV-band.WeconcludethattheAAVSOcalibrationsetsuffersfromnosystematicerror inBorVat thelevelof twopercent. Unfortunately, we could not find any independent measurements tochecktheRandIpassbandsinasimilarmanner. InordertoconverttheRITmeasurementstotheJohnson-Cousinssystem,we analyzed images of the standard field PG1633+009 (Landolt 1992) todeterminethecoefficientsinthetransformationequations


B=b+0.238(043)*(b–v)+ZB (1)

V=v–0.077(010)*(v – r)+ZV (2)

R=r–0.082(038)*(r – i)+ZR (3)

I=i+0.014(013)*(r – i)+ZI (4)

Intheequationsabove,lower-casesymbolsrepresentinstrumentalmagnitudes,upper-case symbols Johnson-Cousins magnitudes, terms in parentheses theuncertaintiesineachcoefficient,andZthezeropointineachband.WeusedstarsA,B,andGtodeterminethezeropointforeachimage(exceptinafewcasesforwhichGfelloutsidetheimage).Table2listsourcalibratedmeasurementsofSN2011femadeatRIT.ThefirstcolumnshowsthemeanJulianDateofalltheexposurestakenduringeachnight.Inmostcases,thespanbetweenthefirstandlastexposureswaslessthan0.04day,butonafewnights,cloudsinterruptedthesequenceofobservations.ContactthefirstauthorforadatasetprovidingtheJulianDateofeachmeasurementindividually. The uncertainties listed in Table 2 incorporate the uncertainties ininstrumentalmagnitudesandintheoffsettoshifttheinstrumentalvaluestothestandardscale,addedinquadrature.Asacheckontheirsize,wechosearegionofthelightcurve,875<JD–2455000<930,inwhichthemagnitudeappearedtobea linear functionof time.Wefitastraight line to themeasurements ineachpassband,weightingeachpointbasedon itsuncertainty; theresultsareshown inTable3.The reducedc2values,between0.9and1.6, indicate thatouruncertaintiesaccuratelyreflectthescatterfromonenighttothenext.Thedecline rate is smallest in the blue, but it is still, at roughly 130 days afterexplosion,significantlyfasterthanthe0.0098mag/dayproducedbythedecayof56Co. TheMSUdataweretransformedinasimilarway,usingonlystarsAandB.ThetransformationequationsforMSUwere

B=b+0.25(0.03)*(b – v)+ZB (5)

V=v–0.08(0.02)*(b – v)+ZV (6)

I=i+0.03(0.02)*(v – i)+ZI (7)

Intheequationsabove,lower-casesymbolsrepresentinstrumentalmagnitudes,upper-case symbols Johnson-Cousins magnitudes, terms in parentheses theuncertaintiesineachcoefficient,andZthezeropointineachband. Table4listsourcalibratedmeasurementsofSN2011femadeatMSU.DuetothelargerapertureoftheMSUtelescope,exposuretimeswereshortenough


thattherangebetweenthefirstandlastexposuresoneachnightwaslessthan0.01day.

4. Light curves

WeadopttheexplosiondateofJD2455796.687±0.014deducedbyNugentet al.(2011b)inthefollowingdiscussion.Figure3showsourlightcurvesofSN2011fe,whichstart2.9daysaftertheexplosionand1.1daysafterNugentet al.(2011a)announcedtheirdiscovery. In order to determine the time and magnitude at peak brightness, wefit polynomials of order 2 and 3 to the light curves near maximum in eachpassband,weightingthefitsbytheuncertaintiesineachmeasurement.Welisttheresults inTable5, includingthevaluesfor thesecondarymaximuminI-band.Weagainuselow-orderpolynomialfitstomeasurethedeclineintheB-band15daysafterthepeak,findingD15(B)=1.21±0.03.Thisvalueissimilartothatofthe“normal’’SNeIa1980N(Hamuyet al.1991),1989B(Wellset al.1994),1994D(Richmondet al.(1995),and2003du(Stanishevet al.2007).ThelocationofthesecondarypeakinI-band,26.6±0.5daysafterand0.45±0.03magbelowtheprimarypeak,alsoliesclosetothevaluesforthoseotherSNe. AlthoughthereisasyetlittlepublishedanalysisofthespectraofSN2011fe,(Nugent et al. 2011b) state that the optical spectrum on UT 2011 Aug 25resembles that of the SN 1994D; on the other hand, (Marion 2011) reportsthat a near-infrared spectrum on UT 2011Aug 26 resembles that of SNe IawithfastdeclineratesandDm15(B)>1.3.Wemustwaitfordetailedanalysisofspectraofthiseventasitevolvestoandpastmaximumlightforasecurespectralclassification,butthisverypreliminaryinformationmaysupport thephotometricevidencethatSN2011fefallsintothenormalsubsetoftypeIaSNe. WeturnnowtotheevolutionofSN2011feincolor.Inordertocompareits colors easily to those of other supernovae, we must remove the effectsof extinction due to gas and dust within the Milky Way and within M101.Fortunately,thereappearstobelittleinterveningmaterial.Schlegelet al.(1998)useinfraredmapsofdustintheMilkyWaytoestimateE(B–V)=0.009inthedirectionofM101.Patatet al.(2011)acquiredhigh-resolutionspectroscopyofSN2011feandidentifiedanumberofnarrowNaID2absorptionfeatures;theyuseradialvelocitiestoassignsometotheMilkyWayandsometoM101.Theyconvertthetotalequivalentwidthofallcomponents,85mÅ,toareddeningofE(B–V)= 0.025±0.003usingtherelationshipgiveninMunariandZwitter(1997).Note,however,thatthistotalequivalentwidthisconsiderablysmallerthanthatofallbutasinglestarinthesampleusedbyMunariandZwitter(1997),sowehavedecidedtodoublethequoteduncertainty.AdoptingtheconversionsfromreddeningtoextinctiongiveninSchlegelet al.(1998),wecomputetheextinctiontowardSN2011fetobeAB=0.11±0.03,AV=0.08±0.02,AR=0.07±0.02,andAI=0.05±0.01.


Afterremovingthisextinctionfromourmeasurements,weshowthecolorevolutionofSN2011feinFigures4through6.TheshapeandextremevaluesofthesecolorsaresimilartothoseofthenormalTypeIaSNe1994Dand2003du.InFigure4,wehavedrawna line torepresent therelationship(Lira(1995);Phillipset al.(1999))forasetoffourtypeIaSNewhichsufferedlittleornoextinction.The(B−V)locusofSN2011feliesslightly(0.05to0.10mag)totheredsideofthisline,especiallynearthetimeofmaximum(B−V)color.GivenourestimatesoftheextinctiontoSN2011fe,thissmalldifferenceisunlikelytobeduetoourunderestimationofthereddening.

5. Absolute magnitudes

InordertocomputethepeakabsolutemagnitudesofSN2011fe,wemustremove the effects of extinction and apply the appropriate correction for itsdistance.Theprevioussectiondiscussestheextinctiontothisevent,andwenowexaminethedistancetoM101.SincethefirstidentificationofCepheidsinthisgalaxy26yearsago(Cooket al.1986),astronomershaveacquiredeverdeeperand larger collectionsofmeasurements.Shappee andStanek (2011)providea listof recentefforts,whichsuggests thatCepheid-basedmeasurementsareconvergingonarelativedistancemodulus(m – M)=10.63magbetweentheLMCandM101.Ifweadoptadistancemodulusof(m – M)LMC=18.50magtotheLMC,thisimpliesadistancemodulus(m – M)M101=29.13toM101.Thisissimilartooneofthetworesultsbasedontheluminosityofthetipoftheredgiantbranch,(m – M)M101=29.05±0.06(rand)±0.12(sys)mag(ShappeeandStanek 2011), though considerably less than the other, (m – M)M101 = 29.42± 0.11 mag (Sakai et al. 2004). We therefore adopt a value of (m – M)M101= 29.10 ± 0.15 mag to convert our apparent to absolute magnitudes. Notethattheuncertaintyinthisdistancemodulusisourroughaverage,basedonacombinationoftherandomandsystematicerrorsquotedbyotherauthorsandthescatterbetweentheirvalues.ThisuncertaintyinthedistancetoM101willdominatetheuncertaintiesinallabsolutemagnitudescomputedbelow. Using this distance modulus, and the extinction derived earlier for eachband,wecanconverttheapparentmagnitudesatmaximumlightintoabsolutemagnitudes.WelistthesevaluesinTable6. Phillips (1993) foundaconnectionbetween theabsolutemagnitudeof atypeIaSNandtherateatwhichitdeclinesaftermaximum:quickly-decliningevents are intrinsically less luminous. Further investigation (Hamuy et al.1996; Riess et al. 1996; Perlmutter et al. 1997) confirmed this relationshipand spawnedseveraldifferentmethods toquantify it.Weadopt theDm15(B)method,whichcharacterizesaneventbythechangeinitsB-bandluminosityinthe15daysaftermaximumlight.ThelightcurveofSN2011feyieldsDm15(B)= 1.21 ± 0.03 mag, placing it in the middle of the range of values for SNeIa.Prietoet al.(2006)computelinearrelationshipsbetweentheDm15(B)and


peak absolute magnitudes for a large sample of SNe. If we insert our valueofDm15(B)intotheequationsfromtheirTable3forhostgalaxieswithsmallreddening,wederivetheabsolutemagnitudesshownintherightmostcolumnofTable6.TheexcellentagreementwiththeobservedvaluessuggeststhatourchoiceofdistancemodulustoM101maybeagoodone.

6. Comparison with visual measurements

PerhapsbecauseitwasthebrightestSNIatoappearintheskysince1972,SN 2011fe was observed intensively by many astronomers. The AAVSOreceivedover900visualmeasurementsoftheeventwithinsixmonthsoftheexplosion.SinceitwasobservedsowellwithbothhumaneyesandCCDs,thisstarprovidesanidealopportunitytocomparethetwodetectorsquantitatively. WeacquiredvisualmeasurementsmadebyalargesetofobserversfromtheAAVSO;notethatthesehavenotyetbeenvalidated.Weremovedasmallnumber of obvious outliers, leaving 880 measurements over the range 799<JD–2455000 < 984. For each of our CCD V-band measurements, weestimatedasimultaneousvisualmagnitudebyfittinganunweightedlow-orderpolynomialtothevisualmeasurementswithinNdays;duetothedecreasingfrequencyofvisualmeasurementsandthelesssharplychanginglightcurveatlatetimes,weincreasedNfrom5daysto8daysatJD2455840andagainto30daysatJD2455865.WethencomputedthedifferencebetweenthepolynomialandtheV-bandmeasurement.Figure7showsourresults:thereisacleartrendforthevisualmeasurementstoberelativelyfainterwhentheobjectisred.Ifwemakeanunweightedlinearfittoallthedifferences,wefind

(visual–V)2011fe=–0.09+0.19(04)*(B – V) (8)

wherethenumberinparenthesesrepresentstheuncertaintyinthecoefficient. WeknowoftwoothercasesinwhichvisualandothermeasurementsoftypeIaSNearecompared.PierceandJacoby(1995)retrievedphotographicfilmsofSN1937C,whichwereoriginallydescribedinBaadeandZwicky(1938),re-measured themwithaphotodensitometer,andcalibrated theresults to theJohnsonV-bandusingasetoflocalstandards.TheycomparedtheirresultstothevisualmeasurementsofSN1937CmadebyBeyer(1939)andfound

(visual–V)1937C=–0.63+0.53*(B – V) (9)

WeplotthisrelationshipinFigure7usingadottedline.JacobyandPierce(1996)discussedthedifferencesbetweenvisualmeasurementsofSN1991TfromtheAAVSO to CCD V-band measurements made by Phillips et al. (1992). WehaveextractedthemeasurementsofPhillipset al.(1992)fromtheirFigure2andcomparedthemtothevisualmeasurements,usingthemedianofallvisual


measurementswithinarangeof0.5daytodefineavaluecorrespondingtoeachCCDmeasurement.WeshowthesedifferencesascircularsymbolsinFigure7;anunweightedlinearfityields

(visual–V)1991T=–0.28+0.68(10)*(B – V) (10)

Wefindtheslopetobethemoreinterestingquantityintheserelationships,sincetheconstantoffsettermmaydependonthechoiceofcomparisonstarsforvisualobservers.Althoughatfirstblushtheslopesappeartobequitedifferent,ifoneexaminesFigure7carefully,onewillseethatthetrendisquitesimilarforallthreeSNeifonerestrictsthecolorrangeto(B – V)>0.5.Themaindifferencebetween these three events, then, lies in the measurements made when theSNe were relatively blue. Could that difference be real? We note that SNe1991T (definitely) and 1937C (probably) were events with slowly declininglightcurvesandhigher thanaverage luminosities,whileSN2011fedeclinedat an average rate and, for our assumed distance to M101, was of averageluminosity.AsPhillipset al.(1992)describes,thespectrumofSN1991TwasmostdifferentfromthatofordinarySNeIaatearlytimes,beforeandduringitsmaximumluminosity;itisalsoattheseearlytimesthatSNeshinewithbluelight.CouldthecombinationofphotometrybythehumaneyeandphotometrybyCCDreallydistinguishordinaryandsuperluminousSNeIaatearlytimes?Theevidenceisfartooweakatthistimetosupportsuchaconclusion,butwelookforwardtotestingtheideawithfutureevents. Stanton(1999)undertookamoregeneralstudy,comparingthemeasurementsofasetofroughlytwentystarsnearSSCygmadebymanyvisualobserverstotheJohnsonVasafunctionof(B – V).Hefoundarelationship

(visual–V)=0.21*(B – V) (11)

whichweplotwithadash-dottedlineinFigure7.TheslopeofthisrelationshipisconsistentwiththatderivedfromtheentireSN2011fedataset.

7. Conclusion

OurmulticolorphotometrysuggeststhatSN2011fewasa“normal’’typeIaSN,withadeclineparameterDm15(B)=1.21±0.03mag.AftercorrectingforextinctionandadoptingadistancemodulustoM101of(m – M)=29.10mag,wefindabsolutemagnitudesofMB=–19.21,MV=–19.19,MR=–19.18,andMI=–18.94,whichprovidefurtherevidencethatthiseventwas“normal’’initsopticalproperties.Assuch,itshouldserveasanexemplaroftheSNewhichcan act as standardizable candles for cosmological studies.Acomparisonofthe visual and CCD V-band measurements of SN 2011fe reveals systematicdifferencesasafunctionofcolorwhicharesimilartothosefoundforothertypeIaSNeandforstarsingeneral.


8. Acknowledgements

WeacknowledgewiththanksthevariablestarobservationsfromtheAAVSOInternational Database contributed by observers worldwide and used in thisresearch.WethankArneHendenandthestaffatAAVSOformakingspecialeffortstoprovideasequenceofcomparisonstarsnearM101,andforhelpingtocoordinateeffortstostudythisparticularvariablestar.MWRisgratefulforthecontinuedsupportoftheRITObservatorybyRITanditsCollegeofScience.WithoutthePalomarTransientFactory,theastronomicalcommunitywouldnothave received such early notice of this explosion.We thank the anonymousrefereeforhiscomments.

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Table1:Photometryofcomparisonstars. Star R.A. (J2000) Dec. (J2000) B V h m s ° ' " R I

A 140313.67 +541543.4 14.767±0.065 13.832±0.027 13.290±0.030 12.725±0.037

B 140254.17 +541629.5 14.616±0.080 13.986±0.037 13.627±0.039 13.262±0.044

G 140231.15 +541403.9 15.330±0.084 14.642±0.042 14.283±0.042 13.931±0.073


799.56 14.072±0.038 13.776±0.016 13.728±0.011 13.696±0.022 * 800.58 13.321±0.046 13.025±0.013 12.955±0.024 12.942±0.026 802.56 12.148±0.028 12.049±0.011 11.941±0.020 11.882±0.022 803.55 11.690±0.023 11.643±0.016 11.512±0.015 11.471±0.024 804.56 11.310±0.025 11.300±0.009 11.170±0.012 11.147±0.017 806.54 — 10.659±0.020 10.572±0.028 10.569±0.052 * 808.54 10.346±0.045 10.466±0.029 10.336±0.011 10.402±0.025 814.53 10.034±0.039 10.014±0.003 10.042±0.084 10.260±0.030 * 815.53 9.981±0.015 10.012±0.012 10.011±0.025 10.320±0.027 816.53 10.072±0.052 9.998±0.008 10.006±0.035 10.362±0.036 817.58 10.060±0.072 9.903±0.059 10.031±0.031 10.307±0.019 * 820.53 10.171±0.010 10.082±0.013 10.080±0.014 10.505±0.018 * 822.52 10.326±0.017 10.134±0.006 10.181±0.002 10.630±0.026 823.53 10.405±0.015 10.185±0.014 10.283±0.015 10.691±0.013 825.52 10.623±0.030 10.311±0.009 10.428±0.027 10.840±0.018 827.51 10.829±0.028 10.459±0.016 10.580±0.024 10.918±0.025 829.51 11.043±0.057 10.574±0.019 10.655±0.017 10.898±0.020 830.52 11.167±0.014 10.629±0.011 10.672±0.021 10.894±0.015 832.51 11.423±0.058 10.739±0.011 10.731±0.012 10.855±0.018 * 839.53 12.228±0.016 11.116±0.016 10.850±0.008 10.699±0.033 * 840.50 12.312±0.039 11.180±0.013 10.865±0.024 10.661±0.026 841.50 12.407±0.049 11.237±0.011 10.925±0.016 10.672±0.031 842.50 12.503±0.038 11.294±0.006 10.958±0.015 10.680±0.026 844.50 12.688±0.035 11.430±0.016 11.054±0.016 10.738±0.045 * 852.90 13.098±0.021 11.921±0.014 11.615±0.033 11.255±0.022 858.48 13.314±0.034 12.144±0.020 11.862±0.013 11.564±0.024 * 859.49 13.290±0.016 12.157±0.010 11.879±0.012 11.634±0.047 * 864.90 13.340±0.037 12.332±0.012 12.085±0.013 11.884±0.010 868.49 13.364±0.017 12.441±0.014 12.190±0.016 12.038±0.040 870.90 13.375±0.011 12.478±0.016 12.256±0.008 12.141±0.005 872.88 13.371±0.041 12.509±0.016 12.343±0.021 12.179±0.008 * 883.92 13.584±0.006 12.826±0.010 12.688±0.011 12.676±0.014 887.92 13.598±0.012 12.927±0.006 12.796±0.005 12.832±0.013 889.92 13.699±0.037 12.968±0.019 12.904±0.026 12.909±0.012 890.93 13.658±0.021 12.988±0.019 12.902±0.011 12.957±0.018 898.91 13.761±0.037 13.217±0.014 13.155±0.019 13.245±0.027 905.94 13.831±0.033 13.398±0.013 13.353±0.017 13.470±0.036 907.92 13.877±0.026 13.442±0.018 13.445±0.027 13.580±0.039 913.89 13.919±0.035 13.559±0.019 13.624±0.027 13.732±0.025 * 924.92 14.078±0.036 13.811±0.016 13.945±0.025 14.066±0.032 *

Table2.RITphotometryofSN2011fe. JD–2455000 B V R I note



932.94 14.191±0.032 14.006±0.022 14.145±0.020 14.256±0.045 * 935.98 14.219±0.041 14.054±0.017 14.280±0.027 14.384±0.039 * 937.92 14.253±0.026 14.124±0.015 14.325±0.026 14.423±0.036 942.72 14.298±0.038 14.204±0.025 14.402±0.058 14.506±0.043 * 945.89 14.377±0.033 14.272±0.033 14.523±0.036 14.627±0.045 * 948.86 14.420±0.036 14.336±0.023 14.639±0.031 14.702±0.050 954.82 14.524±0.044 14.465±0.021 14.757±0.028 14.803±0.040 966.90 14.716±0.033 14.623±0.024 14.951±0.032 15.034±0.053 973.67 14.792±0.044 14.754±0.039 15.165±0.060 15.174±0.056 978.67 14.884±0.046 14.894±0.026 15.340±0.048 15.242±0.054

Table2.RITphotometryofSN2011fe,cont. JD–2455000 B V R I note

* clouds

Table3.Linearfittolightcurves2455875<JD<2455930. Passband Slope (mag/day) reduced c2

B 0.0117±0.0006 1.2 V 0.0247±0.0004 1.6 R 0.0312±0.0004 0.9 I 0.0346±0.0006 1.0

801.58 12.66±0.02 12.42±0.02 12.36±0.03 803.56 11.69±0.01 11.60±0.01 11.48±0.02 806.58 10.80±0.01 10.74±0.01 10.66±0.02 809.56 10.36±0.02 10.30±0.01 10.28±0.02 811.56 10.17±0.03 10.08±0.03 10.22±0.02 * 820.54 10.13±0.02 10.06±0.01 10.44±0.02 822.53 10.27±0.02 10.10±0.01 10.55±0.01 825.54 10.55±0.03 10.27±0.02 10.87±0.02 * 837.52 11.93±0.02 10.97±0.02 10.66±0.03 851.50 13.04±0.03 11.83±0.02 11.16±0.03 857.90 13.18±0.05 12.09±0.04 11.42±0.04 * 867.48 13.27±0.04 12.37±0.03 11.96±0.03 889.46 13.61±0.03 12.92±0.03 12.89±0.03 898.47 13.67±0.10 13.14±0.06 13.22±0.08

Table4.MSUphotometryofSN2011fe. JD–2455000 B V I note

* clouds


B 816.0±0.3 10.00±0.02 V 817.0±0.3 9.99±0.01 R 816.6±0.4 9.99±0.02 I 813.1±0.4 10.21±0.03 I(sec) 839.7±0.5 10.66±0.01

Table5.Apparentmagnitudesatmaximumlight. Passband JD–2455000 Magnitude

B –19.21±0.15 –19.25±0.03 V –19.19±0.15 –19.18±0.03 R –19.18±0.15 –19.19±0.04 I –18.94±0.15 –18.92±0.03 I(sec) –18.49±0.15 —

Table6.Absolutemagnitudesatmaximumlight,correctedforextinction. Passband Observed Based on Dm15

b magnitude a

a Based on (m – M)M101 = 29.10 ± 0.15 mag.b Using the relationship from Prieto etal. (2006).

Figure1.AV-bandimageofM101fromRIT,showingstarsusedtocalibratemeasurementsofSN2011fe.Northisup,Easttotheleft.Thefieldofviewisroughly13by9arcminutes.


Figure2.Differencebetweeninstrumentalmagnitudesextractedfrommedian-combinedimagesandfromindividualimagesatRIT.Thevalueshavebeenshiftedforclarityby0.4,0.0,–0.4,–0.8magnitudeinB,V,R,I,respectively.

Figure3.LightcurvesofSN2011feinBVRI.Thedataforeachpassbandhavebeenoffsetverticallyforclarity.

Figure4.(B–V)colorevolutionofSN2011fe,aftercorrectingforextinction.


Figure5.(V–R)colorevolutionofSN2011fe,aftercorrectingforextinction.

Figure6.(R–I)colorevolutionofSN2011fe,aftercorrectingforextinction.

Figure7.ThedifferencebetweenvisualandCCDorphotographicmeasurements,asafunctionof(B–V)color,forSNeIaandforvariablestarsingeneral.

Luberda and Osborn, JAAVSO Volume 40, 2012 887

New Light Curve for the 1909 Outburst of RT Serpentis

Grant LuberdaWayne OsbornYerkes Observatory, 373 W. Geneva St., Williams Bay, WI 53191; email correspondence should be sent to [email protected]

Received October 6, 2011; revised October 24, 2011; accepted October 24, 2011

Abstract Anew light curve for the1909outburst of theunusual novaRTSerpentis hasbeenderived.Publishedobservationshavebeen compiled andnew brightness measures determined from archival photographic plates.ModernphotometryhasbeenusedtoplacetheobservationsapproximatelyontheUBVsystem.Theoutbursthadanoverallincreaseofatleast5magnitudesandreachedmaximumin1917MaywithB=11.0andV=10.1

1. Introduction

TheunusualvariableRTSerpentis(=AN7.1917=NovaSer1909;J2000coordinates=R.A.17h39m51.98s,Dec.–11°56'39.0")wasdiscoveredbyWolfin1917(Wolf1917)andindependentlydiscoveredbyBarnardtwoyearslater(Barnard1919a).Asearchofarchivalphotographsshowedtheobjectwasnotvisibleonanyplatespriorto1909butafteroutburstremainednearmaximumbrightnessforseveralyears(Bailey1919,Wolf1919,Shapley1919)afterwhichitbeganaslowdecline(Shapley1927).RTSerisnowclassifiedasoneoftheraresymbioticnovaeobjects(Nussbaumer1992). OurinterestinthisobjectbeganwhenwecameacrossaplateintheYerkescollectionwiththeenvelopenotation“Remarkablevariable.”SomesleuthingrevealedthephotographwasoneofBarnard’sobservationsofRTSerduringoutburst.Oursearchfora lightcurveof theevent revealedonly theoldonepublished by Payne-Gaposchkin and Gaposchkin (1938). It seemed obviousthatderivinganewlightcurvemorecloselytiedtothetraditionalUBVsystemwouldbeworthwhile.

2. Observational Data

WehavecollectedavailableobservationsofthemagnitudeofRTSerpentiswithin twenty-five years of its outburst in 1909, i.e., data prior to 1935.The observations are of two types: magnitudes determined from images onphotographicplatesandvisualestimates.

2.1PhotographicObservations MagnitudesfromphotographicplateshavebeenpublishedbyWolf(1919),

Luberda and Osborn, JAAVSO Volume 40, 2012888

Barnard(1919a,1919b),Bailey(1919,1921),andShapley(1919,1923,1927).Thepublisheddatahavebeensupplementedinthreeways.First,wehavemadeeyeestimatesofthebrightnessofRTSeronforty-twoplatesfoundintheYerkesObservatorycollection.Second,wehaveusedthedigitalcopiesoftheplatesof the University of Heidelberg’s Bruce Telescope that are available online(http://www.lsw.uni-heidelberg.de/projects/scanproject/) both to make eyeestimatesandtodeterminemagnitudesthroughaperturephotometry.Third,wehavedeterminedroughmagnitudesandepochsforthe“unpublishedHarvardobservations”plottedonthePayne-GaposchkinandGaposchkin(1938)lightcurve.

2.2VisualObservations VisualobservationsofRTSeraround the timeof itsoutbursthavebeenpublished by Mundler (1919), Barnard (1919b), Graff (1919, 1921, 1922,1927), and Lacchini (1921, 1929, 1933). We also downloaded the 121 datapointsforRTSerintheAAVSOInternationalDatabase(AAVSO2011)thatarewithinourtimewindow.AreviewoftheAAVSOobservationsshowedthatallbutthreearevisualestimatesbyLacchini.Theyincludehisthirteenpublishedmagnitudeestimatesbutwithmoreaccurateepochs.Forsomereason,however,his first eight observations have AAVSO magnitudes between 0.2 and 0.3magnitude systematically fainter thanhispublishedvalues for those epochs,withthepublisheddatabeingmoreconsistentwithhissubsequentbrightnessestimates.Thereisalsoonecaseofanepochwithaten-daydifference.Wehaveadoptedthepublisheddatainthediscrepantcases.

3. Reductions

We endeavored to place the diverse observations approximately on theUBVsystem.Specifically,pseudo-Bandpseudo-Vmagnitudeswerederivedfor the photographic observations and the visual measures, respectively.WebeganbydeterminingBandVmagnitudesforacomparisonstarsequencethatincludedthestarsthathadbeenusedbytheearlierinvestigators.TheadoptedBandVdataaregiveninTable1alongwiththeidentificationofthestarsandthesourceoftheBVphotometry.TychocataloguedataweretransformedtotheUBVsystemusingtherelationsofBessell(2000);AAVSOdataarefromCCDphotometry on the UBVRcIc system. Given the uncertainties in the RT Sermagnitudes,thecomparisonsequencevaluesareusuallygivenonlytoatenthofamagnitude.

3.1Photographicdata ThephotographicdatasetsarefromtheYerkes,Heidelberg,andHarvardplatecollections.EyeestimatesofthebrightnessofRTSerusingourcomparisonsequencehavebeenmadefortheYerkesplates.ThesedataaregiveninTable2


whichliststheplatenumber,theJuliandateofmid-exposure,andthepseudo-Bmagnitude.Thefirstdigitsoftheplatenumberindicatetheapertureofthecameraemployed,withtwoormoreexposuresoftenbeingtakensimultaneouslywithdifferentlenses. Wolf (1919) published magnitudes from Heidelberg plates taken withtelescopes of three different apertures. Some plates—those taken with the41-cm (16-inch) Bruce Telescope—have been digitized and are availableonline.Wedownloaded thedigitized imagesofplatesshowingRTSerandboth performed aperture photometry and made eye-estimates using ourcomparisonsequence;ourresultsaregiveninTable3.Thesedatashowedthatacorrectionof+2.0magisneededtoconvertWolf’spublishedmagnitudestoapproximateBones,andthisfactorwasusedtotransformthepublisheddatafortheundigitizedplates. The observations from the Harvard plates were more difficult to adjust.Magnitudesaregiveninsixdifferentreferences(Bailey1919,1921;Shapley1919,1923,1927;Payne-GaposchkinandGaposchkin1938).Severalgivethemagnitudefromthecritical1909July9plate,andwecomparedthedifferentvalues to each other and to an eye-estimate we were able to make for thisplateusingourcomparisonsequence.OuranalysisindicatesthatallHarvardobservations other than those of Shapley (1919) are on the same system(referred toas the“HarvardSystem”).Anempiricallyderivedadjustmentof+0.6 magnitude was used to transform the Harvard system to our pseudo-Bsystem;thecorrectionusedforthe1919Shapleydatawas+0.1magnitude.

3.2VisualObservations Ingeneral,thevisualobserverslistedthecomparisonstarsusedandtheiradoptedmagnitudes.Wecomparedthelistedcomparisonstarmagnitudeswiththestars’Vonestoobtaincorrectionsfortransformingthevisualobservationsapproximately to theV system.The adopted corrections were +1.0 mag forBarnard’sobservations,+0.9magforGraff’s,and+1.1magforLacchini’sandfor theAAVSOdata.Mundler’sobservationsweremadewithaphotometer;thecorrectionaveraged0.0magbutdependedslightlyonwhichcomparisonstarsheusedforagivenobservation.Weestimateourzeropointshiftsmaybeuncertainbyuptothreetenthsofamagnitude.

4. Results

OurderivedBandVlightcurvesareshowninFigure1.TheBlightcurveincludesdatafromplatesofthefieldtakenbeforetheoutburst.Noevidenceoftheprecursorwasseenonplatesextendingbackto1891(Bailey1919),withthedeepestonesreachingpast16thmagnitude.Therisetomaximumtookplacebetween1908June,whentheBmagnitudewaslessthan16.4,and1910March,when the B magnitude was approximately 12. Unfortunately, few plates are


availablethatwereexposedduringthetimeofrise.ThereisaHarvardplateof1909July9thatdefinitelyshowsRTSer.Oneofus(WO)hadtheopportunitytobrieflyexaminethisplateandthebrightnesswasestimatedatabout14.9usingour comparison sequence; the value from the corrected Harvard observers’estimatesput itat14.5.WealsofoundtwopossibleimagesofRTSerat theplatelimitonthedigitizedHeidelbergplatesof1909June9;theseindicateamagnitudeofroughly14.5. From1910to1917, thenova’smagnitudegradually increasedaboutonemagnitude, reaching a maximum of about B = 11.0 around 1917 May (JD2421350).ThiswaswhentheobjectwasdiscoveredbyWolfandbegantobefollowedbythevisualobservers.ThemaximuminVwas10.1,indicatingaB-Vofapproximately0.9. Aftermaximum, thebrightnessbeganadecline,witharateofabout0.4magnitude/yearforfouryearsafterwhich theratedecreasedto less than0.1magnitude/year.By1928both theBandtheVmagnitudeshaddecreasedtoabout 13.0.Thus, the B–V in the 1930s was approximately zero, indicatingthenova’scolorshiftedtowardtheblueasitsbrightnessdecreased.Thislikelyreflects thegradual spectraldevelopmentof strongemission lines,whichby1928dominatethespectrum(AdamsandJoy1928);theselineswouldenhancethe photographic brightness relative to thevisual.Other novae, suchTPyx,havealsoshownsimilarcolorevolution(Schaefer2010).Wecaution,however,thatboththevisualandphotographicestimatesforthelateryearsareuncertain.Inparticular,thephotographicdataafterJD2425100arefromtheunpublishedobservationsplottedonPayne-Gaposchkin’sgraphwhilethevisualobserversnodoubtreliedoncomparisonstarsforwhichonlyphotographicmagnitudeswereavailableforthesefainterestimates.Lastly,wenotewedonotfindstrongevidenceofthebrightnessfluctuationspreviouslyreported.

5. Acknowledgements

WewouldliketothankLeeRobbins,UniversityofToronto;AlisonDoane,curatorof theHarvardplate stacks;HolgerMandelandMarkusDemleitner,ZentrumfürAstronomieHeidelberg;andElizabethWaagen,AAVSO,fortheirhelpingatheringdataneededforthisstudy.ThisresearchmadeuseofNASA’sAstrophysicsDataSystem;theSIMBADdatabase,operatedatCDS,Strasbourg,France;andtheDigitizedSkySurveys(DSS)producedattheSpaceTelescopeScienceInstituteunderU.S.GovernmentgrantNAGW-2166.TheDSSimagesarefromphotographicdataobtainedusingtheOschinSchmidtTelescopeonPalomarMountainandtheUKSchmidtTelescopethroughfundingprovidedbyTheNationalGeographicSociety,theNationalScienceFoundation,theSloanFoundation,theSamuelOschinFoundation,theEastmanKodakCorporation,andtheUKScienceandEngineeringResearchCouncil.Finally,wethanktherefereeforsomeexcellentcommentsandquestionsthathelpedimprovethepaper.


References

AAVSO2011, observations from theAAVSO InternationalDatabase (http://www.aavso.org).

Adams,W.S.,andJoy,A.H.1928,Publ. Astron. Soc. Pacific,40,252.Bailey,S.I.1919,Bull. Harvard Coll. Obs.,No.680,1.Bailey,S.I.1921,Bull. Harvard Coll. Obs.,No.753,2.Barnard,E.E.1919a,Astron. J.,32,37.Barnard,E.E.1919b,Astron. J.,32,48.Bessell,M.S.2000,Publ. Astron. Soc. Pacific,112,961.Graff,K.1919,Astron. Nach.,210,61.Graff,K.1921,Beob.-Zirk. Astron. Nach.,No.32,55.Graff,K.1922,Beob.-Zirk. Astron. Nach.,No.25,45.Graff,K.1927,Beob.-Zirk. Astron. Nach.,No.12,23.Lacchini,G.1921,Beob.-Zirk. Astron. Nach.,No.35,59.Lacchini,G.1929,Beob.-Zirk. Astron. Nach.,No.5,12.Lacchini,G.1933,Astron. Nach.,248,366.Mundler,M.1919,Astron. Nach.,210,157.Nussbaumer,H.1992,inEvolutionary Processes in Interacting Binary Stars,

Proc.IAUSymp.151,eds.Y.Kondo,R.F.Sistero,R.S.Polidan,Kluwer,Dordrecht,andBoston,429.

Payne-Gaposchkin, C., and Gaposchkin, S. 1938, Variable Stars, HarvardMonogr.,No.5,263.

Schaefer,B.E.2010,Astrophys. J., Suppl. Ser.,187,275.Shapley,H.1919,Publ. Astron. Soc. Pacific,31,226.Shapley,H.1923,Bull. Harvard Coll. Obs.,No.789,3.Shapley,H.1927,Bull. Harvard Coll. Obs.,No.851,3.Wolf,M.1917,Astron. Nach.,204,293.Wolf,M.1919,Astron. Nach.,208,363.


6B-12 2414813.708 <14.4 10B-979 2420684.697 11.2 10B-89 2416664.717 <12.0 6B-979 2420684.697 11.0 6B-89 2416664.717 <12.9 10B-1268 2421780.695 11.2 10B-90 2416674.733 <15.6 6B-1268 2421780.695 11.2 6B-90 2416674.733 <15.6 10B-1331.52421998.938 11.1 10B-99 2416693.635 <15.0 6B-1331.5 2421998.938 11.1 6B-99 2416693.635 <15.6 10B-1340 2422020.930 11.1 10B-100 2416695.6 <14.7 6B-1340 2422020.930 11.0 6B-100 2416695.6 <14.7 10B-1345 2422045.887 11.1 10B-224 2417017.717 <17.3 6B-1345 2422045.887 11.0 6B-224 2417017.717 <14.7 10B-1355 2422088.852 11.0 3B-224 2417017.717 <14.7 6B-1355 2422088.852 11.0

Other ID R.A. (2000) Dec. (2000) B V Photometry Source h m s ° ' "

BD–114436 17:40:31.79 –12:04:51.2 11.3 9.95 Tycho,HeidelbergBD–114426 17:38:40.93 –11:49:36.5 11.65 10.1 Tycho,HeidelbergBD–114433 17:39:48.19 –11:50:22.1 10.75 10.15 Tycho,HeidelbergBD–124801 17:40:07.36 –12:05:05.5 11.2 10.65 Tycho,HeidelbergBD–114434 17:39:56.77 –11:46:26.3 12.5 10.95 Tycho,HeidelbergAAVSO110 17:40:48.90 –11:58:33.0 11.5 11.0 Tycho,HeidelbergTYC5668-51-117:39:55.85 –12:08:20.9 11.55 11.25 Tycho,HeidelbergAAVSO114 17:40:48.67 –12:05:54.0 12.0 11.4 Tycho,HeidelbergAAVSO120 17:40:03.12 –11:55:55.6 12.9 11.95 AAVSOAAVSO123 17:39:36.41 –11:52:26.6 13.2 12.3 AAVSOAAVSO130 17:39:32.60 –12:01:26.4 14.5 13.0 AAVSOAAVSO132 17:40:13.09 –11:57:23.9 14.7 13.2 AAVSOAAVSO136 17:39:43.93 –11:52:16.2 14.4 13.6 AAVSOAAVSO139 17:39:32.47 –11:53:51.3 15.0 13.9 AAVSOAAVSO145 17:39:38.53 –11:56:44.1 15.6 14.5 AAVSOAAVSO150 17:39:54.62 –11:57:24.2 16.2 15.0 AAVSOAAVSO153 17:39:45.19 –11:58:01.7 16.4 15.3 AAVSOAAVSO160 17:39:52.31 –11:53:56.3 17.3 16.0 AAVSOAAVSO164 17:39:52.27 –11:57:16.0 17.9 16.4 AAVSOAAVSO174 17:39:49.93 –11:57:10.5 18.5 17.4 AAVSOPhotometry references: AAVSO = sequence star magnitudes listed by AAVSO from CCD photometry, Heidelberg = values from our aperture photometry of Heidelberg plates, Tycho = data in Tycho–2 catalog transformed as per Bessell (2000).

Table1.ComparisonstarsequenceforRTSer.

Plate Julian Date B Plate Julian Date B

Table2.MagnitudesofRTSerfromeye-estimatesofYerkesplates.



10B-457 2418122.720 <16.4 10B-1366 2422249.551 11.1 6B-457 2418122.720 <16.2 6B-1366 2422249.551 11.1 10B-689 2419158.816 11.8 10B-1423 2422470.866 11.2 6B-689 2419158.816 11.8 6B-1423 2422470.866 11.3 10B-702 2419209.736 11.8 6B-702 2419209.736 11.7 10R-44 2424319.667 12.4 10B-977 2420681.682 11.2 10R-346 2425449.822 12.9 6B-977 2420681.682 11.2 10B-978 2420683.702 11.2 24R-5434 2429455.673 14.8 6B-978 2420683.702 11.2 24R-5435 2429455.709 14.8


B479a 2415910.459 <14.7 B1784a 2417742.506 <14.7 B480b 2415910.460 <14.7 B1785b 2417742.506 <15.5 B483a 2415912.522 <15.3 B2338a 2418467.467 14.5 B484b 2415912.522 <15.3 B2339b 2418467.467 14.5 B996a 2416636.461 <15.0 B3945a 2421375.485 11.0 B997b 2416636.461 <15.0 B3946b 2421375.485 11.0 B1002a 2416645.479 <15.0 B3949a 2421394.468 11.0 B1003b 2416645.479 <14.7 B3950b 2421394.468 11.0 B1225a 2416994.544 <13.2 B4765a 2423608.478 11.3 B1226b 2416994.544 <13.2 B4766b 2423608.478 11.3 B1249a 2417025.479 <16.4 B4878a 2423936.477 11.5 B1250b 2417025.479 <16.4 B4879b 2423936.477 11.4

Table3.MagnitudesofRTSerfromaperturephotometryofdigitalcopiesofHeidelbergplates.


Table2.MagnitudesofRTSerfromeye-estimatesofYerkesplates,cont.

Figure 1. The newlight curve of the 1909outburst of RT Ser.Open triangles are Vmagnitudes,filledcirclesare B magnitudes, andthe dashes show the Bmagnitude plate limitwhen the star was toofainttobedetected.

Pollmann and Bauer, JAAVSO Volume 40, 2012894

International Observing Campaign: Photometry and Spectroscopy of P Cygni

Ernst PollmannEmil-Nolde-Str. 12, 51375 Leverkusen, Germany; [email protected]

Thilo BauerHeimerzheimer Str. 2, 53332 Bornheim, Germany


Abstract In this combined campaign on the Luminous Blue Variablestar PCygni we are trying for the first time by way of contemporaneousmeasurementsofphotometricVbrightnessandHaequivalentwidth(EW)torealizea longtermmonitoringof the intrinsicHa-line flux.Thephotometricobservers of AAVSO and BAV (Germany) and a spectroscopic observergroup(Japan,France,Spain,Germany)startedobservingforthiscampaigninNovember2008attherequestofBerndHanischandoneofus(EP)inorderto continue former investigations whose results were based on multi-dailyaveragingofVandEW.AdditionaldatafromliteratureenableustorepresentthequantitativebehavioroftheHa-linefluxforthetimespanAugust2005toDecember2011,whichbehaviorreflectsvariabilitiesinmass-lossrate,stellarwinddensity,andionizationstructure.

1. Introduction

The international observing campaign, Photometry and Spectroscopy ofPCygni, begun in 2008 by Bernd Hanisch and one of us (EP) (Templeton2008a,2008b),isacooperativeprojectoftheAmericanAssociationofVariableStar Observers (AAVSO), Active-Spectroscopy-in-Astronomy (ASPA), andBundesdeutsche Arbeitsgemeinschaft für Veränderliche Sterne (BAV). Onegoal of the campaign is the monitoring of the behavior of the Hα-line equivalent width(EW)andthecontemporaneouschangesoftheV-bandmagnitudeofPCyg.Anothergoalistogatherfurtherinformationabouttheintrinsicfluxofthisspectralline. Asbackgrounditshouldbementionedthatalotofdifferentinvestigationsduringthelastdecadeshavebeencarriedouttoclarifythecausesofbrightnessandemissionstrengthvariationandpossiblelinksbetweenthem,theextensionsof the Hα-emitting wind, and line structures in different spectral areas. One of the earliest interesting investigations of the Hα emission was performed by Scuderiet al.(1992)inordertodeterminepropertiesofthemass-loss. Fiveyearslater,Najarroet al.(1997)carriedoutadetailedparameterstudyofthelinestrength,lineshape,andenergydistributionfortheHandHeIspectrum,

Pollmann and Bauer, JAAVSO Volume 40, 2012 895

in order to understand the nature of P Cygni and its wind. de Jager (2001)describedphotosphericmodelstoexplainoutwardmotionsintheatmospherein context of luminosity and brightness variations. The investigation of thelong-term spectral and quasi-simultaneous photometric behavior of P CygniofMarkovaet al.(2001a,2001b)wasthemainimpetustostartourcampaign. The (for us) important question of the quantitative evaluation of the Hα emissionand its reference to the radialdistributionof theemitting regionsaroundPCygwasinvestigatedinacomprehensiveinterferometricstudybyBalan et al. (2010). Relative to our investigation, it seems to give certainparallelsinthecurrentstudyofRichardsonet al.(2011).Theyareshowinginlong-termstudiesthecorrelationbehaviorofthecontinuumfluxand(notcontemporaneous)photometricV-data, and theyconclude that theyvary indifferentmannerincontextoflong-termandshort-termtimescales(thenon-contemporaneous nature of their data is one of the substantial differencesfromcampaign). InourcampaignitisassumedthatthevariabilityoftheEWiscausedbyvariationsofthecontinuumfluxandnotbyvariationsofthelineflux,whichwouldindicatevariationsinthestellarwinddensity.Therefore,thevariabilityofthecontinuumfluxshallbeourprimaryconcernwhenthepropertiesofthestellarwindsandrateofmasslossarestudied. Photometricandspectroscopicchanges inPCygniareshowntobeanti-correlatedonshort-andlong-termscales.Weobservedatotalchangeof35Åinthe equivalent width (EW) of the Hα line and of ~ 0.25 magnitude in the V-band brightness.OurobservationsextendfromJD2454671(23July2008)throughJD2455880(14November2011).

2. Results

Figures1and2illustrateourobservations.Figure1comparesofthebehaviorof the V magnitude (top) and the Hα-EW (below) during our campaign. Figure 2 is a plot of the Hα-EW (black points) as a function of photometric V magnitude (opencircles)ofPCygfromMarkovaet al.(2001b). AscanbeseeninFigure1,whentheEWdecreases,thecontemporaneousstellarbrightnessincreasesandviceversa.Sofar,ourownresultsinFigure1agree well with the results of Markova et al. (2001b), which are shown inFigure2forcomparison.Strictanti-correlationisexpectedifthevariationofthe continuum flux is independent from variations of the EW. If the Hα line fluxisconstantovertime,anincreaseofthecontinuumbrightnesswillyieldasmallerlinefluxfromthemeasuredEWandviceversa. To find out if and how the flux obtained from the spectral line profilesvaries, the EW measurements are corrected for the effect mentioned in theprevioussection.Fromthedefinitionsof


(1)

and the relation between stellar magnitudes and continuum flux variationsF2/F1=10–0.4(m2–m1),itfollowsthatthelinefluxisF=CEW/10(0.4Vphot). HereCisaconstantfactor.Inpractice,wecorrectEWwithasimpledivisionby10(0.4*Vphot).Thederivedquantityisthennotthelinefluxinphysicalunits,butaquantityproportionaltothephysicallineflux,correctedforcontinuumvariations. It is important to consider the absolute flux of the line becauseitsvariationsarecausedbytheeffectsofmassloss,stellarwinddensity,andchangesoftheionizationstateofchemicalelementsinit. Inthecurrentcampaignwehavealreadyobtained122nearlysimultaneousmeasurements of the EW and the flux in the V-band (Figure 3). Strictlyapplied, the continuum flux at 6563 Å should be used. But here ΔV is a good approximationsincethecolorindicesofPCygnidonotvarygreatly(Markovaet al.2001b,p.903). Figure3attemptstodisplayifandtowhatextenttheintrinsiclineflux(acontinuum-corrected EW) depends onV-magnitude. From a statistical pointofviewonecansaythatthelow0.25correlationcoefficient(whichshouldbezeroafter thecontinuumcorrection),withconsiderationof themeasurementuncertainties, suggests the conclusion that the Hα line flux is independent of V-magnitude.Withconsiderationofstandarddeviationandpossiblyotherkindsof errors, the temporal variation of the line flux of Hα in the plot in Figure 4 will representtheresultofvariationsinthemasslossrate,stellarwinddensity,andchangesoftheionization.The122EWandcontemporaneousV-measurementsof the current campaign are, of course, froma statistical point of view, stillnot sufficient to make firm statements regarding the simultaneous temporalbehaviorofVandtheintrinsiclineflux.Inordertoachievethisaim,furthermultiyear,simultaneousspectroscopicandphotometricmeasurementswillbecontinuedinthiscampaign.Maybethenwewillhaveaopportunitytoreporthereagainaboutthestateoftheresults.3. Acknowledgements

Wearegrateful toDr.DietrichBaade(ESO-München),Dr.OtmarStahl(Landes, Sternwarte Heidelberg), and Prof. Dr. Edward Geyer (formerlyDirector Observatorium Hoher List, University Bonn) for their criticalcommentswhich led to essential improvementsof thiswork.Wealsooffermany thanks to all the participants of the campaign for their worthwhilecontributionsandmeasurements. Thefollowingobserverstookpartattheproject:AAVSO(V-magnitude)—AdrianOrmsby,RobertE.Crumrine, JimFox,KateHutton,NickStoikidis,DavidB.Williams,E.G.Williams,CharlesL.Calia,ThomasL.Peairs,Jeffery

lo – l

l l

o

dlEW=∫


G.Horne,MikeDurkin,DesmondLoughney,WolfgangVollmann;Spectroscopy(Hα-EW)—Mitsugu Fuji, Benjamin Mauclaire, Joan Guarro, Bernd Hanisch, Ernst Pollmann, Thierry Garrel, Valerie Desnaux, Olivier Thizy, Jean NoelTerry,ChristianBuil,StephaneCharbonnel,PierreDubreul,AlainLopez(fromBalanet al.(2010)). TheEW,V(phot),andlinefluxdataareavailableatthefollowingwebsite:http://astrospectroscopy.de/Data_PCyg_Campaign/Data%20table%20of%20the%20campaign.txt References

Balan,A.,Tycner,C.,Zavala,R.T.,Benson,J.A.,Hutter,D.J.,andTempleton,M.2010,Astrophys. J.,139,2269.

deJager,C.2001,inP Cygni 2000: 400 Years of Progress,ed.M.deGroot,C.Sterken,ASPConf.Ser.233,Astron.Soc.Pacific,215.

Markova,N.,Morrison,N.,Kolka,I.,andMarkov,H.2001a,Astron. Astrophys.,376,898.

Markova,N.,Scuderi,S.,deGroot,M.,Markov,H.,andPanagia,N.2001b,Astron. Astrophys.,366,935.

Najarro,F.,Hillier,D.J.,andStahl,O.1997,Astron. Astrophys.,326,1117.Richardson,N.D.,Morrison,N.D.,Gies,D.R.,Markova,N.,Hesselbach,E.

N.,andPercy,J.R.2011,Astron. J.,141,120.Scuderi,S.,Bonanno,G.,diBenedetto,R.,Spadaro,D.,andPanagia,N.1992,

Astrophys. J.,392,201.Templeton,M.R.2008a,AAVSO Special Notice,No.131(http://www.aavso.

org/node/1555/2811).Templeton, M. R. 2008b, Campaign page (http://www.aavso.org/lont-term-

photometric-campaign-luminous-blue-variable-p-cygni).


Figure1.Photometricandspectroscopicobservations:V-magnitude(top)andthe Hα-EW (bottom) of P Cyg during the campaign (including data of Balan et al.2010).

Figure 2. Plot of the Hα-EW (black points) as a function of photometric V-magnitude(opencircles)ofPCyg(fromMarkovaet al.2001b).


Figure 4. Intrinsic flux of the Hα line of P Cyg, 22 August (JD 2453605) to 15 December2011(JD2455911).

Figure3.TherelationshipbetweenlinefluxandV-magnitudeofPCyg.

Percy and Fu, JAAVSO Volume 40, 2012900

The Pulsation Period of the Hot Hydrogen-Deficient Star MV Sagittarii

John R. PercyRong FuDepartment of Astronomy and Astrophysics, University of Toronto, Toronto. ON, M5S 3H4, Canada; [email protected]

Received January 20, 2012; revised April 30, 2012; accepted April 30, 2012

Abstract MV Sgr is a hot, hydrogen-deficient star which has undergoneRCrB fadings. We have used self-correlation analysis and Fourier analysisofCCDV-bandphotometryintheAAVSOInternationalDatabasetoidentifyaperiodof8.0daysin thisstar; theamplitudeisabout0.03magnitude.Thevariabilityismostlikelyduetopulsation.

1. Introduction

Hydrogen-deficient stars (Clayton 1996; Werner and Rauch 2008) are ararebutverydiverse(Jeffery2008a)groupofobjects,inadvancedandunusualstagesofevolution. In thispaper,weareconcernedwithhydrogen-deficientstars which can undergo the R CrB phenomenon—unpredictable fadings,followedbyslowreturn tomaximumbrightness.Mostof theapproximatelyfiftysuchstarsinourgalaxyarecool—“classical”RCrBstars—butafewhotmembersofthegrouphavebeendiscovered. Therearetwoproposedmechanismsforproducing“classical”RCrBstars:themergerofaheliumwhitedwarfandacarbon-oxygenwhitedwarf,andafinalheliumshellflash(Ibenet al.1996;SaioandJeffery2002).Observationalevidenceseemstofavortheformermechanism,thoughafewRCrBstarsmaybeproducedbythelattermechanism(Clayton2011).Thehothydrogen-deficientstarsdonotnecessarilyarisefromthesamemechanism(s)asthecoolones,andmayinfacthavediverseevolutionaryhistories(DeMarcoet al.2002). ManyRCrBstarsarealsopulsatingvariables,andthepulsationmaybepartly responsible for the mass loss that leads to the fadings. Pulsating hothydrogen-deficient variable stars have been classified as PV Tel stars, butJeffery(2008b)arguesthatthisclassificationshouldbereplacedbythreenewclasses,basedonthepulsationperiodandmodeinthestar. MVSgr(AAVSO1838–21,HV4168,V~13.35)wasdiscoveredtobeanRCrBstarin1928byMissIdaWoods(Hoffleit1959),andhasbeenstudiedbyvarioustechniquessincethen(DeMarcoet al.2002).ItsatmosphericpropertiesareTeff=16,000±500Kandlogg=2.48±0.30,andpulsationshadnotbeenfoundinMVSgrasof2008(Jeffery2008b). SinceobservationsofthisstarhavebeenmadebyAAVSOobservers,oneof

Percy and Fu, JAAVSO Volume 40, 2012 901

thepurposesofthispaperistoprovidefeedbacktotheobservers,showingthekindofsciencethatcanbedonewiththeirobservations.Anadditionalpurposeistodemonstratehowundergraduatestudents(suchasco-authorFu)cancarryoutusefulresearchwitharchivalvariablestardata.

2. Data, analysis, and results

VisualandCCDV-banddatawere takenfromtheAmericanAssociationofVariableStarObserversInternationalDatabase(AID;Henden2012).Therewereatotalof2,315visualobservations,and138CCDV-bandobservations.Theformerweremadeby33differentobservers;thelatterweremadebyG.DiScala,M.Simonsen,J.Temprano,andD.Wells. ThemostnumerousV-bandobservationswereintheseasonJD2455644–2455852. Self-correlation analysis (Percy and Mohammed 2004) of theseshowedaclearperiodofabout8.0days,withafullamplitudeofabout0.03magnitude,andatleasteightrepeatingminima,indicatingcoherentvariability(Figure1).Self-correlationanaysisofthewholeV-banddatasetshowedaperiodof8.0±0.1days,withasimilaramplitude.Themeanerroroftheobservations,asdeterminedfromtheinterceptontheverticalaxis,is0.03magnitude.Self-correlationanalysisofthevisualdatadidnotshowadetectablesignal,whichisprobablyduetothesmallamplitudeandthemuchhighernoiselevel. TheanalysiswasrepeatedwithFourieranalysis,usingtheperiod04software(Lenz and Breger 2005). For the V-band data, in the season JD 2455644–2455852,and in thewholedataset, thehighestpeakswereat frequenciesof0.128cycle/day(period7.8days)andand0.122cycle/day(period8.2days),respectively;thelatterspectrumisshowninFigure2.Ineachcase,thehighestpeak was only slightly higher than the next-highest peak. It did, however,agreewiththeperiodfoundfromself-correlationanalysis.Forthevisualdata,thehighestpeakwasatafrequencyof0.204cycle/day(period4.9days),butthiswasonlyslightlyhigherthanthenoiselevel,andmaynotbesignificant,especiallyconsideringthesmallamplitudeandthemuchhighernoiselevelinthevisualdata.

3. Discussion and conclusions

MV Sgr displays a period of 8.0 days, which we assume to be due topulsation.Thesignal isnotstrong,but it isquiteclear intheself-correlationdiagram,andisconsistentwiththeresultsoftheFourieranalysis.ThisenablesustoplacethestarinJeffery’s(2008b)PVTelIsub-class. MV Sgr was not known to be pulsating (Saio and Jeffery 1988; Jeffery2008b).Wenowhaveonemorepieceofusefulinformationaboutthisstar.Also,thediscoveryofpulsationprovidesfurthersupportforthepossibleconnectionbetweenpulsationandtheRCrBphenomenoninhydrogen-deficientstars.

Percy and Fu, JAAVSO Volume 40, 2012902

4. Acknowledgements

WethanktheAAVSOobserversandstaffformakingandarchivingthevisualandCCDobservationsusedinthisstudy,andtherefereeGeoffClaytonforhisuseful suggestions.This studywas supportedby theOntarioWork-StudyProgram.

References

Clayton,G.C.1996,Publ. Astron. Soc. Pacific,108,225.Clayton,G.C.2011,inAsymmetric Planetary Nebulae V,eds.A.A.Zijlstra,F.

Lykou,I.McDonald,andE.Lagadec,JodrellBankCentreforAstrophysics,Manchester,UK,157.

DeMarco,O.,Clayton,G.C.,Herwig,F.,Pollacco,D.L.,Clark, J.S., andKilkenny,D.2002,Astron. J.,123,3387.

Henden,A.A., 2012, Observations from theAAVSO International Database,privatecommunication.

Hoffleit,D.1959,Astron. J.,64,241.Iben,I.,Jr.,Tutukov,A.V.,andYungelson,L.R.1996,Astrophys. J.,456,750.Jeffery,C.S.2008a,inHydrogen-Deficient Stars,eds.K.Werner,andT.Rauch,

ASPConf.Ser.391,Astron.Soc.Pacific,SanFrancisco,3.Jeffery,C.S.2008b,Inf. Bull. Var. Stars,No.5817,1.Lenz,P.,andBreger,M.2005,Commun. Astroseismology,146,53.Percy,J.R.,andMohammed,F.2004,J. Amer. Assoc. Var. Star Obs.,32,9.Saio,H.,andJeffery,C.S.1988,Astrophys. J.,328,714.Saio,H.,andJeffery,C.S.2002,Mon. Not. Roy. Astron. Soc.,333,121.Werner,K.,andRauch,T.,eds.2008,Hydrogen-Deficient Stars,ASPConf.Ser.

391,Astron.Soc.Pacific,SanFrancisco.

Percy and Fu, JAAVSO Volume 40, 2012 903

Figure 2. Fourier spectrum for CCD V-band observations of MV Sgr. Thehighestpeakisatafrequencycorrespondingtoaperiodof8.0days.

Figure1.Self-correlationdiagramforCCDV-bandobservationsofMVSgrduring the season JD 2455644–2455852 when the observations are mostnumerous. There are repeating minima at multiples of 8.0 days: 8, 16, 24(weak),32,40,48,56,64...days,andmaximaat4,12,20,28(weak),36,44,52... indicating coherent variability.These minima and maxima are marked.Theminima(includingatDt=0),donotextendbelow0.025becausethisistheaverageerroroftheobservations.TheminimaandmaximadieoutatlargeDtbecauseofthescarcityofDmagnitudeswiththeseDtvalues.

de Ponthièreet al., JAAVSO Volume 40, 2012904

GEOS RR Lyrae Survey: Blazhko Period Measurement of Three RRab Stars—CX Lyrae, NU Aurigae, and VY Coronae Borealis

Pierre de Ponthière15 Rue Pré Mathy, Lesve, Profondeville 5170, Belgium

Jean–François Le Borgne14, Avenue Edouard Belin, F–31400 Toulouse, France

F. FumagalliCalina Observatory, Carona, Switzerland

Franz–Josef Hambsch12 Oude Bleken, Mol, 2400, Belgium

Tom KrajciP. O. Box 1351, Cloudcroft, NM 88317

J.-M. Llapasset 66 Cours de Lassus, F–66000 Perpignan, France

Kenneth Menzies318A Potter Road, Framingham, MA 01701

Marco Nobilevia Cantonale 53, 6942 Savosa, Switzerland

Richard Sabo2336 Trailcrest Drive, Bozeman, MT 59718

Received December 14, 2011; revised December 28, 2011; accepted January 9, 2012

Abstract We present the results of collaborative observations of three RRLyraestars(CXLyr,NUAur,andVYCrB)whichhaveastrongBlazhkoeffect.ThisworkhasbeeninitiatedandperformedintheframeworkoftheGEOSRRLyrSurvey(GroupeEuropéend’ObservationsStellaires).Fromthemeasuredlightcurves,wehavedeterminedthetimesandthemagnitudesatmaximum.Thetimesofmaximahavebeencomparedtoephemeridestoobtainthe(O–C)valuesandfromaperiodanalysisofthese(O–C)values,theBlazhkoperiodisderived.TheBlazhkoperiodsofNUAur(114.8days)andVYCrB(32.3days)arereportedhereforthefirsttimeandamoreaccurateperiodforCXLyr(68.3days)hasbeenobtained.ThethreestarsaresubjecttostrongBlazhkoeffect,butthiseffecthasdifferentcharacteristicsforeachofthem.Whenwecomparethevariationsofmagnitudeatmaximumandvariationsof(O–C)valueswith

de Ponthièreet al., JAAVSO Volume 40, 2012 905

respect to theBlazhkophase, thesevariationsare inphase, inopposition,oreveninquadrature.

1. Introduction

ThemainobjectiveoftheGEOSRRLyrSurveyistofollowthevariationsofperiodandBlazhkoeffectofbrightandwell-studiedRRLyraestars.Thesevariationsare followed in the long termwithTAROTrobotic telescopes(LeBorgneet al.2007andPorettiet al.2008).ThesecondobjectiveofthesurveyistheobservationofBlazhkoeffectofunder-studiedRRLyraestars.Theresultspresentedhereareinkeepingwiththisobjective. The RR Lyrae stars of Bailey type ab (RRab) are pulsating stars with aperiodbetween0.4and0.7day.SomeRRabstarsexhibitaphaseandamplitudemodulation. This phenomenon, known for a century, is called the Blazhkoeffect.Itisrecognizedthatthiseffectisstillnotwellunderstood.RRabstarsexhibiting the Blazhko effect appear to show a variety of characteristics.Recent continuous, high precision photometry from the Kepler satellitedocuments a period doubling for some RR Lyrae stars (Szabó et al. 2010).Withourground–basedsmallaperturetelescopesandtheirlimitedphotometricaccuracy,weattempttodeterminetheBlazhkoperiodofneglectedRRabstars.MonitoringduringseveralyearsisneededtodeterminetheBlazhkoperiodandtocharacterizetheBlazhkobehavior.Wehaveanalyzedthevariationsofthemagnitudeatmaximumand(O–C)valuewithrespecttotheBlazhkophaseforthreedifferentstars(CXLyr,NUAur,andVYCrB). Afterdarkandflatfieldcorrectionswiththemaxim dlsoftware(DiffractionLimited 2004), aperture photometry was performed using either aip4win(BerryandBurnell2001)orlesvephotometry(dePonthière2010),acustomsoftware which also evaluates the SNR and estimates magnitude errors. Nocolorcorrectionshavebeenappliedtothemeasuredmagnitudes.Thetimesofmaximaofthelightcurveshavebeenevaluatedwiththesamecustomsoftwarefitting the light curve with a smoothing spline function (Reinsch 1967).WehaveusedtheANOVAalgorithmofperanso(Vanmunster2007)toderivetheBlazhkoperiodfromthetimesofmaxima.

2. CX Lyr

ThestarCXLyrisclassifiedintheGeneral Catalogue of Variable Stars (GCVS;Samuset al.2011)asanRRabvariablestarwithaperiodof0.61664495day. CX Lyr observations during the second half of 2008 (JD 2454637 to2454783)havebeenpreviouslyreportedbydePonthièreet al.(2009).Duringanewobservationcampaignfrom2009to2011(JD2455041to2455807),weobtainedforty–onenewmaxima. Thecomparison starsusedby theauthorsaregiven inTable1.The star


coordinatesandmagnitudesinBandVbandswereobtainedfromtheNOMADcatalogue (Zacharias et al. 2011). C1 was used as magnitude reference andtheothers as check stars.The choiceof different comparison stars creates amagnitudeoffsetduetotheircolordifferences.Thisoffsethasbeenevaluatedbycomparingthemagnitudesofacommoncheckstarandtakenintoaccount.Table2providesthelistof thesenewobservationsandFigure1showsthe(O–C)values.Forthesakeofcompleteness,observationsobtainedbyG.Maintz(Huebscheret al.2008,2010)andolderGEOSobservationsareincludedinthetableastheyareusedinthepresentanalysis. A linear regression of all available (O–C) values has provided a newpulsationperiodof0.616758day.The(O–C)valueshavebeenre–evaluatedwiththisnewpulsationperiod.Thenewelementsare:

HJD=2454677.5692±0.0031+(0.6167582±0.0000031)E (1)

Thesevaluesareveryclosetothevaluesreportedpreviously(dePonthiereet al.2009).

HJD=2454677.5688±0.0037+(0.61675±0.000024)E (2)

The Blazhko period was determined by a period analysis of the (O–C)valueswiththeANOVAalgorithm.Themostsignificantperiodis68.3±0.4days(5.34c/y).TheperiodogrampresentedinFigure2indicatesotherpeaksat56.6days(6.45c/y),84.1days(4.34c/y),and113.3days(3.22c/y)whichareone-yearsamplingaliases. Thereisalsoanotherpeakat136days,thatis,twicethemostsignificantperiod.Data from theyear 2010 (JD2455300 to2455500) indicate that thesuccessive Blazhko cycles are not identical (Figure 1). The variations ofsuccessive cycles create spectral response at a multiple of the fundamentalperiod.An (O–C) folded light curve at 136days,would show twomaxima.A similar period analysis of the magnitude at maximum with the ANOVAalgorithmhasprovidedsimilarconclusions. Thefolded(O–C)andmagnitudeatmaximumcurvesversustheBlazhkophasearegiveninFigure3aand3b.Itcanbeseenthatthesetwocurvesarenearlyinphase,withtheminimareachedatthesameBlazhkophase.

3. NU Aur

The star NUAur is classified in the GCVS (Samus et al. 2011) as anRRab variable star with a period of 0.53941672 day and a Blazhko periodof179days.Duringa firstobservationcampaign,betweenDecember2006andFebruary2007(JD2454081to2454135),theeighteenobtainedmaximaclearlyshowedastrongBlazhkoeffectbutdidnotallowadeterminationoftheBlazhkoperiod.Theobservationof seventy–fivemaxima resulted froma second series of observations between December 2008 and March 2011


(JD2454752to2454640).ThecomparisonstarsaredocumentedinTable3.Star coordinates and B and V magnitudes are those found in theAAVSO’sComparisonStarDatabase(VSD).Thetimesofmaximumand(O–C)valuesaregiveninTable4andFigure4.TheobservationsofG.MaintzhavealreadybeenpublishedbyHuebscheret al.(2009)andthoseofK.MenziespublishedbySamolyk(2011). A linear regression on the (O–C) values has provided the followingelements:

HJD=2454752.4603±0.0014+(0.5394148±0.0000015)E (3)

TodeterminetheBlazhkoperiodwehaveperformedaperiodanalysisofthe(O–C)valueswiththeANOVAalgorithm.ThecorrespondingperiodogrampresentedinFig.5aindicatesthatthevaluesofthefourprominentpeaksinclude:

Period(days) Cycles/year Peakvalue

114.4 3.192 49.6 170.1 2.148 56.7 227.1 1.600 47.3 339.6 1.074 53.4

Thefirst twopeaks(114.4±1.7and170.1±2.6days)areanaliaspair.Onefrequencyisthealiasatonecycleperyearoftheother.Thethirdperiod(227.1)daysisapproximatelydoublethefirstone(114.4).Theperiodof170.1daysisclosetothevaluereportedintheGCVS(175days).Thesealiasesareartifactsarisingfromgapsbetweennormal6–monthobservingseasons.WiththeSpectralWindowtoolinperanso,wehavetriedtodeterminewhichpeaksare artifacts of the seasonal sampling. This algorithm calculates the patterncausedbythestructureofgapsintheobservations.TheoutputoftheSpectralWindowisgiveninFigure5b,whereitcanbeseenthattheartifactpeaksarebroad.Thelistofprominentpeaksis:

Period(days) Cycles/year Peakvalue

91.1 4.007 0.08 103.4 3.536 0.06 128.8 2.834 0.07 145.2 2.517 0.16 181.4 2.013 0.12 244.2 1.494 0.28 362.2 1.008 0.60

ThisSpectralWindowanalysisindicatesthatthefirstpeak(114.4days)oftheANOVAanalysis isnotanartifactdue toseasonalsampling.Thesecondpeak(170.1days)isclosetothe181.4peakoftheSpectralWindowanalysisandcouldbeanartifact.TheBlazhkoperiodisprobably114.4±1.7days,but


we can not eliminate the second possible period of 170.1 ± 2.6 days. Moreobservationsareneededtoremovethisambiguity. Usingtheadoptedperiodof114.4days,thefolded(O–C)andmagnitudeatmaximumcurvesversustheBlazhkophasearegiveninFigure6aand6b.ItcanbeseenthatthesetwocurvesarenotinphaseaswasthecaseforCXLyr.ForNUAurstarthetwocurvesareinquadrature.

4. VY CrB

ThestarVYCrBisclassifiedintheGCVS(Samuset al.2011)asanRRabvariablestar.VYCrBisalsodesignatedasGSC2576–0980(SpaceTelescopeScienceInstitute2001).ItwasidentifiedasanRRabstaronphotographicplatesbyAntipin(1996).VYCrBishereinidentifiedasAntipin’sVar23withaperiodof0.462957day. We observed two maxima of VY CrB in April 2007 (JD 2454215 and2454216) and forty–nine maxima betweenApril 2010 andAugust 2011 (JD2455302to2455784).TheselectedcomparisonstarsaregiveninTable5.StarcoordinatesandBandVmagnitudeareobtainedfromtheNOMADcatalogue.Thetimesofmaximumand(O–C)valuesaregiveninTable6andFigure7.ThistablealsoincludesapreviousobservationobtainedbyA.Paschke(AgererandHuebscher2002). A linear regression of the (O–C) values has provided the followingelements:

HJD=2455302.5032±0.0013+(0.4629461±0.0000010)E (4)

Asfortheotherstars,theBlazhkoperiodhasbeenderivedwiththeANOVAalgorithmappliedtothe(O–C)values.ThecorrespondingperiodogramisgiveninFigure8.Theperiodsforthetwoprominentpeaksare:32.3±0.1and64.6±0.2days,whichdifferbyafactoroftwo.AsforCXLyr,thenon–repetitivebehavioroftheBlazhkoeffectgeneratesspectralresponseatmultiplesofthefundamentalperiod.WithaBlazhkoperiodof64.4dayswewouldhavetwo(O–C)maximapercycle,soweretainedtheBlazhkoperiodvalueof32.3±0.1days. Thefolded(O–C)andmagnitudeatmaximumversustheBlazhkoperiodof32.3daysaregiveninFigure9aand9b.Itcanbeseenthatthesetwocurvesareinphaseopposition:themaximumvalueof(O–C)occurswhenthemagnitudeatmaximumisatitsminimumvalue.

5. Blazhko behavior comparison

Itisinterestingtoplotthemagnitudeatmaximumversusthe(O–C)values.If thesequantitieswerevarying in time as sinusoids andwere inphase, theresultinggraphwouldbeastraightlineinthefirstandthirdquadrants.Iftheywere in phase opposition, the graph would be a straight line in the second


andfourthquadrantsand if theywere inquadrature thegraphwouldexhibita circle.Theperiodicalvariationsofmagnitudeatmaximumand the (O–C)valuesarenotsinusoidal,butthecorrespondingparametricrepresentationwillneverthelessprovideusefulinformation. Thesegraphs for the threestarsaregiven inFigure10.For theCXLyr,the points are scattered along two segments forming a right angle but thegeneraltrendisaslopeat45degreesindicatingthat(O–C)andmagnitudeatmaximumare inphaseasshowninFigures3aand3b.Thepointsalong theverticalsegmentcorrespondtotheBlazhkophasesbetween0.0and0.5andtheotherpointsalongthehorizontalsegmentcorrespondtothesecondpartoftheBlazhkoperiod. InthediagramofNUAur,thepointswithamagnitudefainterthan12.9aregroupedonacircle,themagnitudeatmaximumand(O–C)valuesareinphasequadratureasshowninFigures6aand6b.Thegroupofpointswithamagnitudefainter than 12.9 are created by the non–repetitive behavior from Blazhkocycles. The full data set for NUAur covers more than ten Blazhko cycles. IntheVYCrBgraph,thepointsarescatteredalongacurvewithaslopeofabout135degrees.Themagnitudeatmaximumand(O–C)curvesareinphaseopposition. ForCXLyrandVYCrB,the(O–C)errorsarelargerwhenthemagnitudesatmaximumareat theirgreatestvalue.This ispartiallyduetoa lowerSNRbutmainlybecausethelightcurveatmaximumisflatter,whichleadstoalessprecisemaximummeasurement.

6. Conclusions

ThisstudyindicatesthatregularobservationsoverseveralseasonsoryearsbyamateurscanleadtothecharacterizationoftheBlazhkoeffectofRRLyrstars:thisisoneofthemainobjectivesoftheprofessional–amateurprogram“GEOSRRLyrSurvey.”Theseresultsshouldencourageamateurs to join inmeasurementcampaigns. The measurement of RR Lyrae stars having a strong Blazhko effecthighlightsthefactthatthiseffectisnotstandardfromonestartoanother,assatellite-basedobservations(CoRotandKepler)haveshown.Eachstarhasaparticularbehavioranditmaynotrepeatexactlyfromonecycletoanother.AcompleteastrophysicalmodelofBlazhkoeffectforRRabstarsshouldbeabletoexplainthesebehaviordifferences.

7. Acknowledgements

This research made use of the GEOS RR Lyr database http://rr–ly.ast.obs–mip.fr,hostedbyInstitutdeRechercheenAstrophysiqueetPlanétologie,Toulouse,France,andoftheSIMBADdatabase,operatedatCDS,Strasbourg,


France. The authors acknowledge AAVSO Director Arne Henden and theAAVSO for the use of theAAVSONet telescopes at Sonoita (Arizona) andCloudcroft (NewMexico).Theywould also like to thankG.Maintz andA.PaschkefortheircontributionstotheGEOSdatabase. The authors wish to recognize their affiliation with the followingorganizationsorinstitutions:PierredePonthière—AAVSO,GroupeEuropéend’ObservationsStellaires,France(GEOS);Jean–FrançoisLeBorgne—GEOS,UniversitédeToulouse,France;F.Fumagalli—GEOS;Franz–JosefHambsch—AAVSO,BundesdeutscheArbeitsgemeinschaft fürVeränderlicheSternee.V.,Germany(BAV),GEOS,VerenigingVoorSterrenkunde,Belgium(VVS);TomKrajci—AAVSO;KennethMenzies—AAVSO,GEOS;MarcoNobile—GEOS;RichardSabo—AAVSO,GEOS.

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Table1.ComparisonstarsforCXLyr.

Identification R.A. (2000) Dec. (2000) B V B–V DPP Hambsch Sabo h m s ° ' "

GSC2121–2818 185151.48 +284908.15 11.129 10.548 0.581 C1 GSC2121–2053 185137.00 +285116.32 11.054 10.565 0.489 C2 C2GSC2121–1980 185114.25 +284337.01 13.29 12.74 0.55 C3 C1 C1GSC2121–2842 185107.01 +284512.52 13.8 13.1 0.7 C2

2454238.4240 0.0050 –0.0139 –712 — — — F.Fumagalli2454278.5276 0.0014 0.0004 –647 — — — F.Fumagalli2454280.3802 0.0015 0.0027 –644 — — — F.Fumagalli2454362.4056 0.0014 –0.0007 –511 — — — G.Maintz2454637.4929 0.0026 0.0125 –65 12.329 0.050 V F.-J.Hambsch2454661.5051 0.0020 –0.0289 –26 12.308 0.050 V F.-J.Hambsch2454677.5688 0.0018 –0.0009 0 12.152 0.006 V P.dePonthière2454685.5930 0.0020 0.0055 13 12.062 0.026 V P.dePonthière2454692.3815 0.0013 0.0096 24 12.051 0.005 V P.dePonthière2454708.4197 0.0019 0.0121 50 12.235 0.006 V P.dePonthière2454711.5050 0.0040 0.0136 55 12.237 0.040 V P.dePonthière2454719.5020 0.0050 –0.0072 68 12.297 0.026 V P.dePonthière2454724.4300 0.0040 –0.0133 76 12.331 0.007 V P.dePonthière2454729.3630 0.0030 –0.0144 84 12.324 0.006 V P.dePonthière2454750.3518 0.0016 0.0047 118 12.134 0.012 V P.dePonthière2454758.3736 0.0012 0.0086 131 12.156 0.020 V P.dePonthière2454774.4100 0.0030 0.0093 157 12.293 0.020 V P.dePonthière2454782.3940 0.0030 –0.0246 170 12.363 0.022 V P.dePonthière2454983.4954 0.0024 0.0137 496 12.333 0.008 V P.dePonthière2455041.4761 0.0032 0.0191 590 12.158 0.008 V P.dePonthière

Table2.ListofmeasuredmaximaofCXLyr.

Maximum HJD Error O–C (day) E Magnitude Error Filter Observer



Table2.ListofmeasuredmaximaofCXLyr,cont.


2455046.4025 0.0025 0.0115 598 12.296 0.013 V F.-J.Hambsch2455049.4886 0.0035 0.0138 603 12.294 0.010 V P.dePonthière2455052.5695 0.0085 0.0109 608 12.295 0.015 V P.dePonthière2455057.4596 0.0060 –0.0331 616 — — V G.Maintz2455060.5485 0.0084 –0.0279 621 12.371 0.010 V P.dePonthière2455062.3950 0.0010 –0.0317 624 — — V G.Maintz2455062.3977 0.0032 –0.0290 624 12.432 0.009 V F.-J.Hambsch2455094.5062 0.0025 0.0081 676 12.065 0.015 V P.dePonthière2455096.3587 0.0015 0.0103 679 12.042 0.008 V P.dePonthière2455295.5698 0.0015 0.0085 1002 12.087 0.011 V P.dePonthière2455303.5902 0.0012 0.0111 1015 12.021 0.010 V P.dePonthière2455308.5270 0.0020 0.0138 1023 12.024 0.011 V P.dePonthière2455311.6080 0.0025 0.0110 1028 12.073 0.020 V P.dePonthière2455312.8464 0.0018 0.0159 1030 12.162 0.012 V F.-J.Hambsch2455320.8601 0.0019 0.0117 1043 12.307 0.011 V F.-J.Hambsch2455333.7745 0.0040 –0.0258 1064 12.397 0.012 V F.-J.Hambsch2455353.5350 0.0025 –0.0015 1096 12.303 0.012 V P.dePonthière2455363.4131 0.0025 0.0084 1112 12.122 0.030 V P.dePonthière2455369.5828 0.0020 0.0106 1122 12.050 0.010 V P.dePonthière2455374.5167 0.0020 0.0104 1130 12.030 0.010 V P.dePonthière2455379.4518 0.0020 0.0114 1138 12.056 0.009 V P.dePonthière2455382.5342 0.0015 0.0100 1143 12.121 0.009 V P.dePonthière2455387.4662 0.0023 0.0080 1151 12.188 0.010 V P.dePonthière2455392.3970 0.0030 0.0047 1159 12.286 0.010 V P.dePonthière2455395.4753 0.0040 –0.0008 1164 12.337 0.009 V P.dePonthière2455398.5497 0.0074 –0.0102 1169 12.364 0.009 V P.dePonthière2455408.3959 0.0035 –0.0321 1185 12.325 0.010 V P.dePonthière2455429.4044 0.0025 0.0066 1219 12.189 0.011 V P.dePonthière2455440.5115 0.0017 0.0121 1237 11.988 0.009 V P.dePonthière2455442.3601 0.0020 0.0104 1240 11.980 0.012 V P.dePonthière2455445.4485 0.0015 0.0150 1245 12.009 0.008 V P.dePonthière2455461.4862 0.0040 0.0170 1271 12.284 0.011 V P.dePonthière2455470.7015 0.0065 –0.0191 1286 12.427 0.011 V F.-J.Hambsch2455479.3298 0.0047 –0.0254 1300 12.371 0.010 V P.dePonthière2455492.3090 0.0075 0.0019 1321 12.347 0.018 V P.dePonthière2455649.5879 0.0020 0.0075 1576 12.053 0.009 V P.dePonthière2455670.5422 0.0044 –0.0080 1610 12.343 0.010 V P.dePonthière2455713.7302 0.0013 0.0069 1680 12.025 0.006 V K.Menzies2455745.7679 0.0020 –0.0268 1732 12.464 0.004 V R.Sabo2455746.3925 0.0026 –0.0189 1733 12.401 0.013 V P.dePonthière2455807.4625 0.0034 –0.0080 1832 12.366 0.010 V P.dePonthière


Table3.ComparisonstarsforNUAur.

Identification R.A. (2000) Dec. (2000) B V B–V DPP Hambsch Menzies Sabo h m s ° ' "

GSC1857–1453 050858.82 +284208 13.32 12.53 0.795 C1 C1 C1 C1GSC1857–1288 050859.15 +284320.2 13.67 C2 GSC1857–1288 050859.17 +284320.3 14.46 13.77 0.69 C2 C2 C2GSC1857–938 050834.00 +284507.6 13.322 12.326 0.996 C3 C3 C3 C3

2454081.4445 0.0100 0.0204–1244 — — — J.-M.Llapasset2454083.5942 0.0005 0.0125–1240 — — — J.-M.Llapasset2454088.4454 0.0010 0.0089–1231 — — — J.-M.Llapasset2454089.5225 0.0005 0.0072–1229 — — — J.-M.Llapasset2454090.6033 0.0005 0.0092–1227 — — — J.-M.Llapasset2454091.6733 0.0010 0.0003–1225 — — — J.-M.Llapasset2454096.5397 0.0005 0.0120–1216 — — — J.-M.Llapasset2454100.3214 0.0005 0.0178–1209 — — — J.-M.Llapasset2454107.3333 0.0010 0.0173–1196 — — — J.-M.Llapasset2454114.3359 0.0005 0.0075–1183 — — — J.-M.Llapasset2454121.3493 0.0005 0.0085–1170 — — — J.-M.Llapasset2454128.3628 0.0010 0.0096–1157 — — — J.-M.Llapasset2454135.3748 0.0005 0.0092–1144 — — — J.-M.Llapasset2454456.3178 0.0004 –0.0001 –549 — — — G.Maintz2454752.4570 0.0040 0.0000 0 13.042 0.011 C P.dePonthière2454759.4820 0.0030 0.0126 13 13.028 0.008 C P.dePonthière2454774.5770 0.0020 0.0040 41 12.899 0.012 C P.dePonthière2454787.5310 0.0040 0.0120 65 12.860 0.007 C P.dePonthière2454801.0080 0.0030 0.0036 90 12.737 0.005 V P.dePonthière2454804.7820 0.0040 0.0017 97 12.875 0.005 V P.dePonthière2454808.0200 0.0030 0.0032 103 12.845 0.005 V P.dePonthière2454827.4315 0.0018 –0.0043 139 12.854 0.007 C P.dePonthière2454828.5107 0.0017 –0.0039 141 12.838 0.007 C P.dePonthière2454829.5870 0.0030 –0.0064 143 12.846 0.009 C P.dePonthière2454829.5900 0.0020 –0.0034 143 12.852 0.009 V P.dePonthière2454830.6570 0.0030 –0.0153 145 12.878 0.009 V P.dePonthière

Table4.ListofmeasuredmaximaofNUAur.




2454830.6610 0.0030 –0.0113 145 12.902 0.014 V P.dePonthière2454831.7451 0.0017 –0.0060 147 12.849 0.008 V P.dePonthière2454832.8202 0.0016 –0.0097 149 12.875 0.008 V P.dePonthière2454833.9020 0.0030 –0.0067 151 12.891 0.009 V P.dePonthière2454838.7576 0.0014 –0.0059 160 12.931 0.011 V P.dePonthière2454841.4540 0.0050 –0.0066 165 12.927 0.023 V P.dePonthière2454843.6114 0.0018 –0.0068 169 12.936 0.013 V P.dePonthière2454844.6863 0.0012 –0.0108 171 12.902 0.012 V P.dePonthière2454845.7661 0.0015 –0.0098 173 12.900 0.011 V P.dePonthière2454846.3070 0.0020 –0.0083 174 — — — J.-M.Llapasset2454846.8450 0.0020 –0.0097 175 12.898 0.010 V P.dePonthière2454850.6150 0.0020 –0.0156 182 12.904 0.010 V P.dePonthière2454851.6940 0.0040 –0.0155 184 12.946 0.009 V P.dePonthière2454852.7740 0.0020 –0.0143 186 12.932 0.006 V P.dePonthière2454857.6330 0.0040 –0.0100 195 13.018 0.008 V P.dePonthière2454860.3380 0.0050 –0.0021 200 13.021 0.016 V P.dePonthière2454861.4150 0.0040 –0.0039 202 13.040 0.018 V P.dePonthière2454862.4960 0.0040 –0.0018 204 13.034 0.017 V P.dePonthière2454884.6190 0.0018 0.0051 245 13.007 0.008 V P.dePonthière2454887.3170 0.0020 0.0061 250 — — — J.-M.Llapasset2454888.3980 0.0020 0.0083 252 — — — J.-M.Llapasset2454891.6396 0.0030 0.0133 258 13.017 0.011 V P.dePonthière2455100.9247 0.0031 0.0053 646 — — V R.Sabo2455106.8653 0.0036 0.0123 657 12.995 0.019 V F.-J.Hambsch2455113.8751 0.0028 0.0097 670 12.937 0.017 V F.-J.Hambsch2455114.9502 0.0040 0.0060 672 12.961 0.036 V F.-J.Hambsch2455119.8273 0.0035 0.0283 681 12.971 0.019 V F.-J.Hambsch2455120.8963 0.0029 0.0185 683 12.923 0.011 V F.-J.Hambsch2455121.9780 0.0023 0.0214 685 12.889 0.009 V F.-J.Hambsch2455122.5074 0.0030 0.0113 686 12.878 0.010 V F.-J.Hambsch2455127.9098 0.0034 0.0196 696 12.797 0.019 V F.-J.Hambsch2455128.9865 0.0039 0.0175 698 12.783 0.003 V F.-J.Hambsch2455135.9890 0.0120 0.0076 711 12.674 0.008 V F.-J.Hambsch2455155.4042 0.0019 0.0038 747 12.703 0.009 V F.-J.Hambsch2455175.3210 0.0020 –0.0378 784 — — — M.Nobile2455182.9060 0.0032 –0.0046 798 12.890 0.013 V F.-J.Hambsch2455189.3650 0.0040 –0.0186 810 12.867 0.015 V F.-J.Hambsch2455208.8035 0.0030 0.0010 846 13.014 0.008 V F.-J.Hambsch2455241.7199 0.0025 0.0130 907 12.963 0.010 V F.-J.Hambsch

Table4.ListofmeasuredmaximaofNUAur,cont.




2455247.6585 0.0030 0.0180 918 12.862 0.009 V F.-J.Hambsch2455261.6812 0.0048 0.0159 944 12.898 0.009 V F.-J.Hambsch2455479.6006 0.0025 0.0115 1348 12.713 0.013 V P.dePonthière2455481.7610 0.0026 0.0142 1352 12.741 0.010 V F.-J.Hambsch2455492.5516 0.0034 0.0165 1372 12.717 0.026 V P.dePonthière2455511.9491 0.0020 –0.0050 1408 12.686 0.010 V F.-J.Hambsch2455528.6650 0.0024 –0.0110 1439 12.781 0.012 V F.-J.Hambsch2455531.8989 0.0031 –0.0135 1445 12.847 0.010 V F.-J.Hambsch2455538.9143 0.0040 –0.0105 1458 13.014 0.010 V F.-J.Hambsch2455540.5315 0.0075 –0.0116 1461 13.044 0.013 V K.Menzies2455542.6905 0.0041 –0.0103 1465 13.026 0.013 V F.-J.Hambsch2455543.7760 0.0048 –0.0036 1467 13.062 0.011 V F.-J.Hambsch2455545.9362 0.0042 –0.0010 1471 13.016 0.011 V F.-J.Hambsch2455548.6347 0.0036 0.0004 1476 13.066 0.008 V R.Sabo2455554.5716 0.0050 0.0037 1487 13.115 0.013 V K.Menzies2455555.6427 0.0035 –0.0040 1489 13.031 0.011 V K.Menzies2455571.3082 0.0060 0.0184 1518 13.057 0.016 V P.dePonthière2455572.3921 0.0038 0.0235 1520 13.063 0.010 V F.-J.Hambsch2455575.6360 0.0060 0.0309 1526 13.045 0.001 V F.-J.Hambsch2455583.7160 0.0031 0.0197 1541 12.941 0.012 V F.-J.Hambsch2455589.6450 0.0047 0.0151 1552 12.919 0.012 V K.Menzies2455627.3941 0.0030 0.0051 1622 12.767 0.015 V P.dePonthière2455627.3945 0.0016 0.0055 1622 12.775 0.006 V F.-J.Hambsch2455640.3375 0.0040 0.0025 1646 12.787 0.015 V P.dePonthière

Table4.ListofmeasuredmaximaofNUAur,cont.


Table5.ComparisonstarsforVYCrB.

Identification R.A. (2000) Dec. (2000) B V B–V DPP Hambsch Menzies Sabo h m s ° ' "

GSC2576–1883 160645.0 +331935.756 12.26511.638 0.627 C1 C1 C1GSC2576–1372 160553.7 +332017.166 14.97 13.71 1.26 C2 C1 C2GSC2576–740 160613.7 +331905.222 14.36 13.58 0.78 C3 C2 C3 C2GSC2576–1021 160605.5 +332500.460 16.77 14.65 2.12 C4 C3 C4


2451615.5930 0.005 –0.0153–7964 — — — A.Paschke2454215.5169 0.002 0.0089–2348 — — — J.-M.Llapasset2454216.4421 0.002 0.0082–2346 — — — J.-M.Llapasset2455302.4926 0.0013 –0.0105 0 13.480 0.009 C P.dePonthière2455303.4196 0.0018 –0.0094 2 13.510 0.012 C P.dePonthière2455309.4562 0.0031 0.0088 15 13.662 0.009 C P.dePonthière2455310.3791 0.0023 0.0059 17 13.702 0.011 C P.dePonthière2455321.4822 0.0021 –0.0017 41 13.548 0.008 C P.dePonthière2455352.5027 0.0024 0.0015 108 13.602 0.008 C P.dePonthière2455364.5240 0.0014 –0.0138 134 13.376 0.009 C P.dePonthière2455370.5535 0.003 –0.0026 147 13.557 0.013 C P.dePonthière2455371.4812 0.0024 –0.0008 149 13.570 0.009 C P.dePonthière2455377.5180 0.008 0.0177 162 13.733 0.030 C P.dePonthière2455378.4431 0.0053 0.0170 164 13.719 0.014 C P.dePonthière2455384.4469 0.0033 0.0025 177 13.614 0.009 C P.dePonthière2455390.4495 0.0016 –0.0132 190 13.352 0.009 C P.dePonthière2455391.3773 0.0015 –0.0113 192 13.343 0.009 C P.dePonthière2455396.4673 0.0016 –0.0137 203 13.343 0.007 C P.dePonthière2455397.3939 0.0017 –0.0130 205 13.372 0.007 C P.dePonthière2455410.3855 0.0048 0.0161 233 13.737 0.009 C P.dePonthière2455441.3929 0.0029 0.0062 300 13.743 0.014 C P.dePonthière2455461.2817 0.0015 –0.0116 343 13.347 0.008 C P.dePonthière2455480.2825 0.0036 0.0084 384 13.676 0.009 C P.dePonthière2455627.4899 0.003 –0.0007 702 13.555 0.010 C P.dePonthière2455640.4717 0.007 0.0186 730 13.754 0.011 C P.dePonthière2455622.8556 0.0054 –0.0056 692 13.316 0.058 V K.Menzies2455644.6183 0.0026 –0.0013 739 13.581 0.009 C P.dePonthière2455645.5423 0.003 –0.0032 741 13.559 0.009 C P.dePonthière2455646.4724 0.0041 0.0010 743 13.613 0.022 C P.dePonthière2455602.9682 0.005 0.0137 649 13.717 0.015 V F.-J.Hambsch2455608.9772 0.005 0.0044 662 13.680 0.018 V F.-J.Hambsch2455609.9030 0.005 0.0043 664 13.661 0.025 V F.-J.Hambsch2455614.9834 0.0028 –0.0077 675 13.413 0.015 V F.-J.Hambsch2455615.9087 0.003 –0.0083 677 13.370 0.019 V F.-J.Hambsch2455622.8554 0.002 –0.0058 692 13.294 0.012 V F.-J.Hambsch2455629.8069 0.004 0.0016 707 13.582 0.018 V F.-J.Hambsch2455640.9245 0.007 0.0085 731 13.690 0.024 V F.-J.Hambsch2455646.9268 0.003 –0.0075 744 13.432 0.014 V F.-J.Hambsch2455647.8531 0.003 –0.0071 746 13.382 0.013 V F.-J.Hambsch

Table6.ListofmeasuredmaximaofVYCrB.




Table6.ListofmeasuredmaximaofVYCrB,cont.


2455653.8707 0.0022 –0.0078 759 13.276 0.013 V F.-J.Hambsch2455654.7969 0.0019 –0.0075 761 13.276 0.013 V F.-J.Hambsch2455660.8238 0.003 0.0011 774 13.545 0.014 V F.-J.Hambsch2455665.9194 0.0053 0.0043 785 13.695 0.018 V F.-J.Hambsch2455666.8510 0.0044 0.0101 787 13.715 0.020 V F.-J.Hambsch2455671.4845 0.0039 0.0141 797 13.748 0.011 C P.dePonthière2455672.4003 0.0047 0.0040 799 13.769 0.012 C P.dePonthière2455714.5166 0.0013 –0.0077 890 13.337 0.007 C P.dePonthière2455715.4414 0.0014 –0.0088 892 13.325 0.007 C P.dePonthière2455760.8215 0.003 0.0027 990 13.690 0.011 V R.Sabo2455739.5326 0.0041 0.0093 944 13.608 0.009 C P.dePonthière2455775.6294 0.0025 –0.0036 1022 13.494 0.013 V K.Menzies2455784.4199 0.003 –0.0091 1041 13.367 0.010 C P.dePonthière

Figure1.CXLyr(O–C).

Figure2.CXLyr(O–C)periodogram.


Figure3a.CXLyr(O–C)atmaximumversusBlazhkophase.

Figure3b.CXLyrmagnitudeatmaximumversusBlazhkophase.

Figure4.NUAur(O–C).


Figure5a.NUAur(O–C)periodogram.

Figure5b.NUAurspectralwindow.

Figure6a.NUAur(O–C)atmaximumversusBlazhkophase.


Figure6b.NUAurmagnitudeatmaximumversusBlazhkophase.

Figure7.VYCrB(O–C).

Figure8.VYCrB(O–C)periodogram.


Figure9a.VYCrB(O–C)atmaximumversusBlazhkophase.

Figure9b.VYCrBmagnitudeatmaximumversusBlazhkophase.

Figure10a.CXLyrmagnitudeatmaximumversus(O–C)values.


Figure10c.VYCrBmagnitudeatmaximumversus(O–C)values.

Figure10b.NUAurmagnitudeatmaximumversus(O–C)values.

Samolyk, JAAVSO Volume 40, 2012 923

Recent Maxima of 55 Short Period Pulsating Stars

Gerard SamolykP.O. Box 20677, Greenfield, WI 53220; [email protected]

Received January 6, 2012; accepted January 6, 2012

Abstract Thispapercontainstimesofmaximafor55shortperiodpulsatingstars (primarily RR Lyrae and d Scuti stars). This represents the CCDobservations receivedby theAAVSOShortPeriodPulsator (SPP)section in2011alongwithsomeearlierdata.

1. Recent observations

The accompanying list contains times of maxima calculated from CCDobservationsmadebyparticipantsintheAAVSO’sShortPeriodPulsator(SPP)Section.Thislistwillbeweb-archivedandmadeavailablethroughtheAAVSOftp site at ftp:ftp.aavso.org/public/datasets/jsamog402.txt.Theseobservationswere reduced by the writer using the peranso program (Vanmunster 2007).ColumnFindicatesthefilterused.Theerrorestimateisincluded. RRLyrstarsinthislist,alongwithdatafromearlierAAVSOpublications,are included in the GEOS database at: http://rr-lyr.ast.obs-mip.fr/dbrr/dbrr-V1.0_0.php.ThisdatabasedoesnotincludedScutistars. ThelinearelementsintheGeneral Catalogue of Variable Stars(Kholopovet al.1985)wereused tocompute theO–Cvaluesformoststars.Fora fewexceptionswhere theGCVSelementsaremissingorare insignificanterror,lightelementsfromanothersourceareused:VYCrB(Antipin1996),AHLeo(Schmidtet al.1995),VYLMi(HendenandVidal-Sainz1997),andGWUMa(Hintzet al.2001).

References

Antipin,S.V.1996,Inf. Bull Var. Stars,No.4343,1.Henden,A.A.,andVidal-Sainz,J.1997,Inf. Bull Var. Stars,No.4535,1.Hintz,E.G.,Bush,T.C.,andRose,M.B.2005,Astron. J.,130,2876.Kholopov,P.N.,et al.1985,General Catalogue of Variable Stars,4thed.,Moscow.Schmidt,E.G.,Chab,J.R.,andReiswig,D.E.1995,Astron. J.,109,1239.Vanmunster,T.2007,peransoperiodanalysissoftware,http://www.peranso.com

Samolyk, JAAVSO Volume 40, 2012924

SWAnd 55786.7504 85137 –0.3869 V R.Sabo 0.0009SWAnd 55793.8288 85153 –0.3850 V R.Sabo 0.0014SWAnd 55815.9392 85203 –0.3886 V R.Sabo 0.0014SWAnd 55827.8846 85230 –0.3847 V R.Sabo 0.0023SWAnd 55844.6873 85268 –0.3887 V K.Menzies 0.0006SWAnd 55852.6494 85286 –0.3876 V R.Sabo 0.0015SWAnd 55874.7608 85336 –0.3902 V R.Sabo 0.0012XXAnd 55796.8764 23120 –0.4746 V R.Sabo 0.0020XXAnd 55833.7370 23171 –0.4741 V R.Sabo 0.0015ZZAnd 55891.6583 56017 0.0266 V K.Menzies 0.0009ATAnd 55808.8146 21827 –0.0041 V R.Sabo 0.0025ATAnd 55832.8716 21866 –0.0068 V R.Sabo 0.0020ATAnd 55847.6745 21890 –0.0099 V R.Sabo 0.0026ATAnd 55868.6556 21924 –0.0039 V R.Sabo 0.0026ATAnd 55889.6287 21958 –0.0059 V N.Simmons 0.0020DMAnd 55857.7959 31949 0.0667 V K.Menzies 0.0018SWAqr 55777.9087 66798 –0.0022 V R.Sabo 0.0007SWAqr 55790.7716 66826 0.0002 V R.Sabo 0.0009SWAqr 55806.8453 66861 –0.0017 V R.Sabo 0.0010SWAqr 55836.7000 66926 –0.0017 V R.Sabo 0.0010AAAqr 55824.7823 57607 –0.1347 V R.Sabo 0.0015TZAur 55844.8578 91766 0.0127 V K.Menzies 0.0006TZAur 55844.8597 91766 0.0146 V G.Samolyk 0.0011TZAur 55869.9259 91830 0.0136 V R.Sabo 0.0009BHAur 55596.4980 28163 –0.0010 V K.Menzies 0.0012BHAur 55835.9501 28688 0.0039 V R.Sabo 0.0014BHAur 55872.8920 28769 0.0025 V K.Menzies 0.0009BHAur 55919.8685 28872 0.0018 V R.Sabo 0.0012NUAur 55575.6370 30616 0.2937 V K.Menzies 0.0020NUAur 55576.7099 30618 0.2878 V K.Menzies 0.0023NUAur 55589.6434 30642 0.2753 V K.Menzies 0.0031NUAur 55857.7213 31139 0.2631 V K.Menzies 0.0013RSBoo 55683.7390 36872 0.0069 V K.Menzies 0.0015RSBoo 55762.6015 37081 0.0055 V K.Menzies 0.0006STBoo 54957.6753 57491 0.0754 V R.Poklar 0.0018STBoo 55748.6354 58762 0.1041 V K.Menzies 0.0015STBoo 55759.8333 58780 0.1007 V R.Sabo 0.0013STBoo 55791.5561 58831 0.0867 V K.Menzies 0.0010


Table1.RecenttimesofmaximaofstarsintheAAVSORRLyraeprogram. JD(max) Star Hel. Cycle O–C F Observer Error 2400000 +


SZBoo 55624.6954 53526 0.0118 V K.Menzies 0.0020TVBoo 55666.7388 99364 0.0756 V R.Poklar 0.0014TVBoo 55743.6272 99610 0.0744 V K.Menzies 0.0021TWBoo 55746.7935 54212 –0.0665 V R.Sabo 0.0008UUBoo 55647.6959 42815 0.2347 V K.Menzies 0.0014UYCam 55905.759 76170 –0.095 V G.Samolyk 0.004RWCnc 55596.5712 29314 –0.3343 V K.Menzies 0.0024RWCnc 55906.8342 29881 –0.3331 V G.Samolyk 0.0015TTCnc 55615.7041 27813 0.1189 V R.Poklar 0.0012TTCnc 55914.8750 28344 0.0982 V K.Menzies 0.0012RRCet 55826.8102 40948 0.0099 V R.Sabo 0.0020RRCet 55852.8042 40995 0.0116 V R.Sabo 0.0013RRCet 55913.6401 41105 0.0144 V R.Sabo 0.0020RUCet 55897.6386 27412 0.1202 V R.Sabo 0.0037RZCet 55875.7351 43025 –0.1840 V R.Sabo 0.0025RZCet 55896.6656 43066 –0.1885 V R.Poklar 0.0021TUCom 55628.6952 57760 0.1216 V K.Menzies 0.0023TUCom 55648.5661 57803 0.1347 V K.Menzies 0.0018TUCom 55719.6807 57957 0.1307 V K.Menzies 0.0019VYCrB 55760.8200 30207 –0.1321 V R.Sabo 0.0019XXCyg 55798.6319 84108 0.0025 V K.Menzies 0.0004XZCyg 55740.7980 24895 –2.1385 V N.Simmons 0.0011DMCyg 55772.7961 31416 0.0683 V R.Sabo 0.0010DMCyg 55785.8154 31447 0.0720 V R.Sabo 0.0015DMCyg 55797.5700 31475 0.0705 V K.Menzies 0.0008DMCyg 55803.8663 31490 0.0689 V R.Sabo 0.0011DMCyg 55809.7499 31504 0.0745 V R.Sabo 0.0012DMCyg 55825.6998 31542 0.0697 V R.Sabo 0.0012DMCyg 55835.7749 31566 0.0681 V R.Sabo 0.0011DMCyg 55852.5725 31606 0.0713 V K.Menzies 0.0009DMCyg 55862.6500 31630 0.0722 V R.Sabo 0.0013DMCyg 55875.6641 31661 0.0706 V R.Sabo 0.0009RWDra 55754.8872 36976 0.1972 V R.Sabo 0.0008RWDra 55767.7599 37005 0.2253 V R.Sabo 0.0006RWDra 55814.7015 37111 0.2177 V R.Sabo 0.0006RWDra 55825.7456 37136 0.1889 V R.Sabo 0.0009RWDra 55829.7266 37145 0.1836 V R.Sabo 0.0013RWDra 55833.7180 37154 0.1888 V R.Sabo 0.0013


Table1.RecenttimesofmaximaofstarsintheAAVSORRLyraeprogram,cont. JD(max) Star Hel. Cycle O–C F Observer Error 2400000 +


RWDra 55865.6079 37226 0.1887 V R.Sabo 0.0013RWDra 55873.5769 37244 0.1852 V R.Sabo 0.0009XZDra 55733.7791 28973 –0.1425 V K.Menzies 0.0013XZDra 55794.7806 29101 –0.1326 V K.Menzies 0.0007XZDra 55847.6739 29212 –0.1305 V R.Sabo 0.0017XZDra 55874.8360 29269 –0.1287 V R.Sabo 0.0024RRGem 55563.3943 35757 –0.4458 V M.Martinengo 0.0009RRGem 55575.7103 35788 –0.4465 V R.Poklar 0.0008RRGem 55584.4513 35810 –0.4463 V M.Martinengo 0.0008RRGem 55586.4336 35815 –0.4505 V A.Marchini 0.0005RRGem 55596.7671 35841 –0.4471 V G.Samolyk 0.0008RRGem 55603.5197 35858 –0.4488 V K.Menzies 0.0009RRGem 55603.5198 35858 –0.4487 V N.Simmons 0.0009RRGem 55833.9453 36438 –0.4633 V R.Sabo 0.0010RRGem 55862.9464 36511 –0.4659 V R.Sabo 0.0010RRGem 55868.9045 36526 –0.4675 V R.Sabo 0.0009RRGem 55901.8832 36609 –0.4656 V R.Sabo 0.0010RRGem 55915.7883 36644 –0.4663 V R.Sabo 0.0012GQGem 55578.7200 44258 –0.1941 V K.Menzies 0.0019GQGem 55605.5376 44305 –0.1932 V K.Menzies 0.0023TWHer 55741.7979 85577 –0.0142 V R.Sabo 0.0007TWHer 55761.7789 85627 –0.0132 V R.Sabo 0.0006TWHer 55775.7646 85662 –0.0135 V R.Sabo 0.0006TWHer 55797.7417 85717 –0.0144 V R.Sabo 0.0010TWHer 55823.7159 85782 –0.0142 V R.Sabo 0.0006TWHer 55872.4671 85904 –0.0142 V K.Menzies 0.0005VXHer 55767.7440 74702 0.0009 V R.Sabo 0.0010VXHer 55798.7055 74770 –0.0030 V R.Sabo 0.0009VZHer 55751.6914 43065 0.0728 V N.Simmons 0.0010ARHer 55757.8655 30434 –1.3137 V R.Sabo 0.0023ARHer 55798.7326 30521 –1.3390 V R.Sabo 0.0010ARHer 55806.7177 30538 –1.3444 V R.Sabo 0.0012DLHer 55785.7309 29710 0.0390 V R.Sabo 0.0016DYHer 55745.7557 150078 –0.0270 V R.Sabo 0.0007DYHer 55761.8064 150186 –0.0285 V R.Sabo 0.0011DYHer 55777.7105 150293 –0.0279 V R.Sabo 0.0006LSHer 55786.6014 120367 0.0228 V K.Menzies 0.0020SZHya 55611.7238 27795 –0.2801 V G.Samolyk 0.0021




SZHya 55624.6736 27819 –0.2241 V R.Poklar 0.0010SZHya 55639.6686 27847 –0.2718 V G.Samolyk 0.0026SZHya 55653.6876 27873 –0.2211 V R.Poklar 0.0012UUHya 55649.7164 30868 0.0036 V R.Poklar 0.0011DHHya 55648.7256 50046 0.0777 V R.Poklar 0.0009RRLeo 55604.6817 27209 0.1104 V R.Poklar 0.0009RRLeo 55666.6594 27346 0.1102 V K.Menzies 0.0013RRLeo 55905.9802 27875 0.1150 V G.Samolyk 0.0014TVLeo 55635.7908 27635 0.1192 V G.Samolyk 0.0014TVLeo 55664.7188 27678 0.1145 V R.Poklar 0.0018WWLeo 55567.8683 34313 0.0446 V K.Menzies 0.0027WWLeo 55648.6415 34447 0.0365 V G.Samolyk 0.0018WWLeo 55648.6480 34447 0.0430 V K.Menzies 0.0039AALeo 54196.5951 24388 –0.0751 V G.Lubcke 0.0013AHLeo 55576.8477 14856 0.0293 V K.Menzies 0.0018VYLMi 55565.8731 9652 0.0049 V K.Menzies 0.0011VYLMi 55603.7593 9724 0.0086 V K.Menzies 0.0024SZLyn 55838.8355 146965 0.0227 V G.Samolyk 0.0014SZLyn 55875.8397 147272 0.0227 V R.Sabo 0.0008SZLyn 55890.9069 147397 0.0231 V G.Samolyk 0.0007SZLyn 55921.7637 147653 0.0229 V N.Simmons 0.0008SZLyn 55921.8832 147654 0.0219 V N.Simmons 0.0010RZLyr 55747.6734 28488 –0.0232 V G.Samolyk 0.0013RZLyr 55756.8719 28506 –0.0271 V R.Sabo 0.0012RZLyr 55770.6657 28533 –0.0368 V K.Menzies 0.0019RZLyr 55771.6878 28535 –0.0372 V R.Sabo 0.0007RZLyr 55777.8244 28547 –0.0355 V R.Sabo 0.0009RZLyr 55793.6703 28578 –0.0381 V R.Sabo 0.0012RZLyr 55816.6874 28623 –0.0270 V R.Sabo 0.0017RZLyr 55837.6507 28664 –0.0246 V R.Sabo 0.0008RZLyr 55862.7012 28713 –0.0250 V R.Sabo 0.0017CXLyr 55745.7667 36772 1.1336 V R.Sabo 0.0025AVPeg 55744.8970 30623 0.1366 V R.Sabo 0.0015AVPeg 55760.9014 30664 0.1356 V R.Sabo 0.0011AVPeg 55771.8337 30692 0.1374 V R.Sabo 0.0011AVPeg 55792.9147 30746 0.1382 V R.Sabo 0.0010AVPeg 55798.7691 30761 0.1370 V K.Menzies 0.0009AVPeg 55807.7492 30784 0.1384 V R.Sabo 0.0010




AVPeg 55823.7558 30825 0.1397 V R.Sabo 0.0013AVPeg 55832.7326 30848 0.1379 V R.Sabo 0.0010AVPeg 55864.7437 30930 0.1382 V R.Sabo 0.0008AVPeg 55868.6454 30940 0.1362 V K.Menzies 0.0012AVPeg 55872.5512 30950 0.1382 V K.Menzies 0.0006BHPeg 53952.8716 22758 –0.1271 V G.Samolyk 0.0027BHPeg 54372.7303 23413 –0.1188 V G.Samolyk 0.0023BHPeg 55759.8356 25577 –0.1224 V R.Sabo 0.0017BHPeg 55825.8398 25680 –0.1404 V R.Sabo 0.0017BHPeg 55834.8125 25694 –0.1416 V R.Sabo 0.0024RVUMa 54219.6391 19536 0.1079 V G.Lubcke 0.0013RVUMa 55607.9182 22502 0.1211 V G.Samolyk 0.0017RVUMa 55634.6024 22559 0.1259 V N.Simmons 0.0011RVUMa 55634.6039 22559 0.1274 V G.Samolyk 0.0015RVUMa 55763.7830 22835 0.1219 V R.Sabo 0.0013RVUMa 55807.7821 22929 0.1234 V R.Sabo 0.0024AEUMa 55584.5518 232282 0.0002 V G.Samolyk 0.0006AEUMa 55584.6348 232283 –0.0028 V G.Samolyk 0.0007AEUMa 55584.7285 232284 0.0049 V G.Samolyk 0.0011AEUMa 55584.8102 232285 0.0006 V G.Samolyk 0.0006AEUMa 55584.8936 232286 –0.0020 V G.Samolyk 0.0005AEUMa 55584.9814 232287 –0.0003 V G.Samolyk 0.0008AEUMa 55890.7752 235842 0.0029 V G.Samolyk 0.0004AEUMa 55890.8557 235843 –0.0026 V G.Samolyk 0.0007AEUMa 55890.9446 235844 0.0003 V G.Samolyk 0.0007AEUMa 55907.7213 236039 0.0037 V G.Samolyk 0.0009AEUMa 55907.8063 236040 0.0026 V G.Samolyk 0.0006AEUMa 55907.8872 236041 –0.0025 V G.Samolyk 0.0007GWUMa 55921.7701 19301 0.0021 V G.Samolyk 0.0013GWUMa 55921.9671 19302 –0.0041 V G.Samolyk 0.0011


Osborn and Mills, JAAVSO Volume 40, 2012 929

The Ross Variable Stars Revisited. II

Wayne OsbornO. Frank MillsYerkes Observatory, 373 W. Geneva Street, Williams Bay, WI 53191; email correspondence should be sent to [email protected]

Received May 23, 2012; accepted June 15, 2012

Abstract Better magnitudes and epochs have been determined for 190 ofthe379confirmedandsuspectedvariablestarsdiscoveredbyRossfrom1925to1931.Accuratepositionshavebeendeterminedforthoseobjectsforwhichunambiguousidentificationshadbeenlacking.TheseincludeanumberofcasesforwhichRoss’spublishedcoordinateshavelargeerrors.

1. Introduction

This is the second of two papers giving identifications and improvedmagnitudesandepochsforthesuspectedvariablestarsdiscoveredbyF.RossofYerkesObservatoryintheperiod1925and1931.PaperI(OsbornandMills2011)discussedthosestarsinRoss’sfirst,second,seventh,eighth,ninth,andtenthlistsofvariables(Ross1925,1926a,1928b,1929,1930,1931).Thispapergivesourresultsfortheremainingstars—thoseinRoss’sthird,fourth,fifth,andsixthlists(Ross1926b,1927a,1927b,1928a). TherationaleforthisworkalongwithourmethodsweredescribedinPaperIandwillnotberepeatedhere.Wewillmerelysaythatwehavere-examinedtheoriginalphotographicplatesusedbyRossforhisdiscoveriestounambiguouslyidentifytheobjectsanddeterminebettermagnitudesandepochsofobservationthanthosepublishedbyRoss.TheonlychangeinourprocedurewastoincludedatafromtheThird U.S. Naval Observatory CCD Astrograph Catalog(UCAC3;Zachariaset al.2010)indeterminingourapproximateBmagnitudes.

2. Results

Our resultsarepresented inTable1.Thecolumnsgive, respectively, theRoss star number, the corresponding variable star name (and, when needed,anotheridentificationbelow),theJulianDates(actuallyJD–2400000.0)andBmagnitudesforthetwocomparedplates.Theepochsaregeocentric,thatis,theyhavenot been converted toheliocentricones.Following each table arenotesformanyofthestars;thesegivesuchinformationaserrorsdetectedinRoss’spapersandcommentsontheidentification. Ofthe190starsconsideredinthispaper,159arenamedvariables,twenty-twoaresuspectedvariableslistedintheNSVcatalogue(Samuset al.2009),

Osborn and Mills, JAAVSO Volume 40, 2012930

sevenwereobservationsofminorplanets,oneisamissingBDstar,andoneavariableBLLacobject(BaumentandCudworth1981).OftheNSVobjects,wedonotseethevariationseenbyRossforR118usingthesameplatematerial,andthesupposedvariationsofR119andR164maybeduetoplateflaws. The case of R148 is interesting, this being a listing in the Bonner Durchmusterung catalogue (Argelander 1903), BD+34°531, for which Rossfoundthereisnocorrespondingstar(irrespectiveofthefactthatRoss’s1875coordinateswereincorrectlyprecessedfromtheBD’s1855position).Hisnotecardforthisstarhasthecomment“KustnerwritesthiswasintheskycertainlyonOct21,1856.”TousitseemspossiblethatBD+34°531resultedfromsomeerrorbythecompilersoftheBD.Thestarwiththesamenumberinthe+33°zone,BD+33°531,liesatthesamerightascensionandjustslightlysouth.ThefollowingcomparestheBDcatalogueentriesforthetwostars:

BD+34°531(mag.=9.3): R.A.02h43m39.5s,Dec.+34°01.6' (revisedcoordinates) R.A.02h43m40.5s,Dec.+34°00.6' (originallypublishedcoordinates)

BD+33°531(mag.=9.3): R.A.02h43m40.7s,Dec.+33°57.5'

Thatbothstarsliesoclosetothezoneboundary,therevisioninthepositionforthemissingstar,andthesimilarityinnumber,magnitude,andcoordinatesforthetwostarssuggestconfusionwiththedatamayhaveledtotwocatalogueentriesfromtheobservationsofjustoneobject. Withthispaper,alltheRossvariableshavebeenreviewedandwecannowexpandupon Marsden’s (2007) comments concerning theRoss observationsthatwereofminorplanets.Forthefifteensuchcases,theaveragedifferencebetween the actual time of exposure of the plate and Marsden’s computedtimewas0.0dwithanRMSdispersionof0.15d,strongconfirmationthatourJulianDateshavebeencalculatedcorrectly.Theaveragedifferencebetweenourpseudo-BmagnitudesandtheexpectedVmagnitudesfortheminorplanetsis0.9mag,or0.75ifonediscrepantvalueisomitted.Notonlyisthisingoodagreement with the average (B–V) of around 0.8 for minor planets (Zellneret al.1975),itsupportsboththatRoss’sestimateswerevisualmagnitudesandthatourestimatesareapproximatelyontheBsystem. AsmentionedinPaperI,Ross’snotecardscontaincommentsforanumberofthestars,includingsomevisualobservationsbyhimorhiscolleagueswiththe Yerkes 40-inch refractor. This information is presented in an appendix,TableA,soitwillnotbelost.

3. Corrections to paper I

Soon after the publication of Paper I, a reader brought to our attention


severalerrors.Mostinvolvethetenstarswehadnotedas“notlistedinNSVcatalog.” We had used SIMBAD to check for cross identifications betweentheRossvariablesandNSVobjects,butitwaspointedoutthatanumberofNSVobjectshadyettobeincorporatedintotheSIMBADdatabase.Usingtheon-line version of the General Catalogue of Variable Stars (http://www.sai.msu.su/gcvs/cgi-bin/search.htm)alltenobjectsturnedouttoindeedhaveNSVnumbers.TheseidentificationsandafewothercorrectionstoPaperIaregivenTable2.

4. Acknowledgements

This research made use of the SIMBAD database, operated at CDS,Strasbourg,France,andtheDigitizedSkySurveys(DSS)producedattheSpaceTelescopeScienceInstituteunderU.S.GovernmentgrantNAGW-2166.TheDSS images are fromphotographicdataobtainedusing theOschinSchmidtTelescope on Palomar Mountain and the UK Schmidt Telescope throughfundingprovidedbyTheNationalGeographicSociety, theNationalScienceFoundation,theSloanFoundation,theSamuelOschinFoundation,theEastmanKodakCorporation,andtheUKScienceandEngineeringResearchCouncil.

References

Argelander,F.W.A.1903,Bonner Durchmusterung des Nordlichen Himmels,2nd corrected ed. (BD Catalogue), A. Marcus and E. Weber’s Verlag,Bonn.

Baumert,J.H.,andCudworth,K.1981,Inf. Bull. Var. Stars,No.2039,1.Bedient,J.R.2003,Inf. Bull. Var. Stars,No.5478,1.Bidelman,W.P.,andCudworth,K.1981,Inf. Bull. Var. Stars,No.2055,1.Bidelman,W.P.,andvanAltena,W.F.1972,Inf. Bull. Var. Stars,No.744,2.Harwood,M.1960,Ann. Sterrewacht Leiden,21,387.Marsden,B.G.2007,Perem. Zvezdy,27,3.Osborn,W.,andMills,O.F.2011,J. Amer. Assoc. Var. Star Obs.,39,186.Ross,F.E.1925,Astron. J.,36,99(firstlistofvariables).Ross,F.E.1926a,Astron. J.,36,122(secondlistofvariables).Ross,F.E.1926b,Astron. J.,36,167(thirdlistofvariables).Ross,F.E.1926c,Astron. J.,36,172(thirdlistofpropermotionstars).Ross,F.E.1927a,Astron. J.,37,91(fourthlistofvariables).Ross,F.E.1927b,Astron. J.,37,155(fifthlistofvariables).Ross,F.E.1928a,Astron. J.,38,99(sixthlistofvariables).Ross,F.E.1928b,Astron. J.,38,144(seventhlistofvariables).Ross,F.E.1929,Astron. J.,39,140(eighthlistofvariables).Ross,F.E.1930,Astron. J.,40,34(ninthlistofvariables).Ross,F.E.1931,Astron. J.,41,88(tenthlistofvariables).


Samus,N.N.,et al.2012,General Catalogue of Variable Stars,publishedon-lineathttp://www.sai.msu.su/gcvs/cgi-bin/search.htm.

Zacharias,N.,et al.2010,Astron. J.,139,2184.Zellner,B.,Wisniewski,W.Z.,Andersson,L.,andBowell,E.1975,Astron. J.,

80,986.

105 RVDel 17062.949 14.2 24384.707 13.1 106 RXDel 17062.949 13.1 24384.707 15.2: 107 RZDel 17062.949 14.4 24384.707 13.1 108 SSDel 17062.949 13.6 24384.707 <16.6 109 STDel 17062.949 13.3 24384.707 12.5 110 V830Cyg 18447.816 13.5 24460.540 14.8 111 SWDel 17062.949 15.7 24384.707 13.8 112 V833Cyg 18447.816 14.6 24460.540 13.9 113 GRCyg 18447.816 13.0 24460.540 15.7: 114* NSV13523 18447.816 <15.6 24460.540 14.1 2MASS21051394+3837134 115* NSV13558 18447.816 <15.3 24460.540 14.4 2MASS21080005+3734183 116 DUCyg 18447.816 13.8 24460.540 12.1 117 NSV13612 18447.816 14.4 24460.540 15.4 2MASS21133238+4258055 118* NSV13622 18447.816 15.4 24460.540 15.5 2MASS21151328+3828514 119* NSV13624 18447.816 15.5: 24460.540 15.3 2MASS21153512+3639576 120 V837Cyg 18447.816 15.1 24460.540 14.4 121 V1812Cyg 18447.816 13.7 24460.540 16.7 122 V1338Cyg 18447.816 <15.2 24460.540 14.7 123 ELPeg 17791.674 13.5 24475.517 <16.0 124 CXPeg 17791.674 14.1 24475.517 <16.0 125 AXPeg 17791.674 12.7 24475.517 11.8 126 GWCyg 19275.660 15.7 24413.628 13.9 127* AQLac 18542.776 13.1 24413.628 <14.9 128 ELLac 18542.776 13.5 24413.628 <14.9 129 ASLac 19275.660 12.8 24413.628 <16.8 130* AVLac 19275.660 13.6 24413.628 <15.6

Table1.IdentificationsandimproveddataforRossVariables105–294. Ross Variable / First JD B Second JD B Other identification 2400000+ 2400000+



131 UYLac 18542.776 11.6 24413.628 14.0 132 V458Lac 18542.776 12.5 24413.628 13.3 133 DGCas 17793.658 14.2 24473.565 15.5 134 FKCas 17793.658 14.2 24473.565 13.0 135 FNCas 17793.658 13.5 24473.565 15.3: 136* NSV308 24468.681 13.5 Minorplanet(137)Meliboca 137 AHPer 17832.732 13.9 24497.569 <16.4 138 AIPer 17832.732 13.5 24497.569 15.3 139 AKPer 17832.732 12.8 24497.569 <16.8 140 ALPer 17068.872 14.5 24494.628 13.7 141 GHPer 17911.641 12.4 24557.563 13.6 142 EVTau 17910.642 12.8 24497.668 <14.5 143 DQTau 17562.706 12.3 24768.666 15.7 144* V1800Ori 17562.706 15.8 24768.666 <16.8 145 HWMon 16795.951 12.4 24557.645 <14.4 146 UWPup 16795.951 13.6 24557.645 <15.2 147 AOGem 17698.616 12.5 24557.740 16.5 148* BD+34°531 –755.5 24497.569 <15.4 149 NSV1351 19665.796 11.2 24577.543 14.7 2MASS03490755+1430533 150 EPOri 16737.913 14.6 24577.587 13.1 151 FGOri 16737.913 11.5 18955.805 16.4 152 V1802Ori 16737.913 13.8 24577.587 <16.9 153 DGOri 16737.913 13.3 24577.587 <15.4 154 AQAur 16736.844 <15.9 24578.573 14.6 155 DUAur 16736.844 12.8 24578.573 <16.1 156 V1794Ori 17679.590 15.1 24577.643 12.5 157 EQAur 19503.592 13.7 24578.649 13.0 158 AZMon 16937.685 12.6 24584.670 <14.5 159 AHMon 16937.685 15.0 24584.670 12.9 160* NSV3506 16937.685 14.5 24584.670 <15.9 2MASS07172610+0137388 161 HUMon 16937.685 15.7 24584.670 12.7 162 YZPup 16885.761 13.1 24588.603 11.6 163 FFPup 16885.761 <14.4 24588.603 13.0


Table1.IdentificationsandimproveddataforRossVariables105–294,cont. Ross Variable / First JD B Second JD B Other identification 2400000+ 2400000+


164* NSV3982 20566.684 14.2 24591.691 15.2 2MASS08173168+0602094 165 V425Hya 20566.684 13.9 24591.691 14.7 166* NSV4168 19151.703 <15.7 24579.689 13.3 Near08:41:37,+72:27.6 167 VXVir 17623.693 13.8 24624.706 15.5 168* NSV6188 16889.8 14.1 Minorplanet(106)Dione 169 TWUMa 17324.7 12.0 24641.699 13.7: 170 AAVir 16889.8 13.8 24648.667 15.6 171 TWLib 16971.751 <16.0 24639.756 12.7 172 WXSer 18064.655 12.5 24624.765 <15.0 173 UULib 16994.791 17.1: 24646.787 12.6 174 V872Sco 16994.791 <16.6 24646.787 13.5 175 AYHer 16586.707 14.6 24651.718 12.4 176 KTOph 17686.845 <15.9 24671.814 13.3 177 KUOph 17686.845 <16.0 24671.814 13.4 178 VZSer 17686.845 14.6 24671.814 <15.5 179 YZAnd 19630.720 12.2 24886.560 14.6 180 GVCas 18154.727 13.2 24855.547 14.0 181 TZPsc 18995.519 <14.2 24904.572 11.6 182 BBAri 18619.618 <16.8 24846.601 13.2 183 V413Per 19743.601 <17.2: 24914.572 14.3 184* NSV1224 17859.672 16.6 24855.708 14.7 185 KLEri 19027.584 14.0 24879.635 15.2 186 XYTau 19004.600 16.4: 24874.613 13.0 187 NVPer 20457.619 14.5 24904.654 <16.2 188 COOri 18622.795 11.2 24878.708 13.1 189 YYTau 18622.795 15.7: 24878.708 13.6 190* NSV2777 18622.795 13.4 Minorplanet(714)Ulula 191 EOOri 16938.688 14.8 24943.1 13.1 192 DDOri 16938.688 11.8 24943.1 12.8 193 FTMon 17616.693 12.8 24879.732 14.5 194* NSV2975 16938.688 14.4 24943.1 13.7 2MASS06285910+0819492




195 VXMon 16938.688 14.6 24943.1 12.9 196 EEGem 16938.688 <16.4 24943.1 13.9 197 AYMon 16938.688 15.7 24943.1 12.8 198 UZMon 18216.922 11.8 24907.722 <14.9 199 VZCMi 18216.922 <14.4 24907.722 12.0 200* OI090.4 20569.668 14.1 24886.845 15.4 201 STCnc 20569.668 15.9 24886.845 14.0 202 SUCnc 20569.668 12.5 24886.845 <14.3 203 VWCnc 20569.668 16.4 24886.845 13.3 204* NSV4018 24948.607 13.2 Minorplanet(554)Peraga 205* TUHya 20567.684 11.5 24913.729 <15.9 206* NSV5338 18406.601 12.1 Minorplanet(26)Proserpina 207* ASHer 18447.681 10.1 24684.703 14.7 208 V2582Oph 18447.681 <15.6 24684.703 13.3 209 V440Oph 18447.681 12.6 24684.703 <15.6 210 V2588Oph 18447.681 14.0 24684.703 15.1 211 BIHer 17656.887 13.9 24668.765 <16.0 212 MWHer 17656.887 <16.6 24668.765 12.4 213 V374Oph 17656.887 13.7 24668.765 <16.0 214 CYAql 16653.832 13.9 24830.516 15.1: 215 EMAql 16653.832 16.4 24830.516 12.8 216 DMAql 16653.832 11.7 24830.516 14.8 217 ESAql 16653.832 13.0 24830.516 <15.5 218* V986Aql 16653.832 14.6 24830.516 <14.7 219 V607Aql 16653.832 13.6 24830.516 <15.5 220 GTAql 16653.832 14.6 24830.516 <14.9 221 EGPeg 19237.686 13.2 24849.540 <15.7 222 VXCep 18179.694 12.0 24851.551 <14.8 223 EYPeg 17471.621 14.6 24841.515 13.3 224 NSV14639 20072.558 14.0 24879.531 16.2 2MASSJ23364663+1643317 225* NSV14640 20072.558 14.5 24879.531 <16.8 2MASSJ23364891+1643341 226 V419Peg 20072.558 15.2 24879.531 14.2




227 EOCas 18179.694 15.6 24851.551 13.5 228* DUPeg 19630.720 12.5 24886.560 15.4 229 TYCnc 20576.610 13.7 24918.639 12.6 230* NSV4333 20576.610 12.4 Minorplanet(389)Industria 231* NSV4352 20576.610 13.9 Minorplanet(242)Kriemhild 232 SWCnc 20576.610 12.9 24918.639 11.7 233 ALHya 20576.610 14.6 24918.639 12.4 234 VXCrv 16963.717 13.4 24994.676 <15.9 235 UCrv 16963.717 11.4 24994.676 15.9 236 VCrv 16963.717 12.8 24994.676 <15.8 237 V429Sct 18525.643 14.2 25142.589 16.5 238 CISct 18525.643 14.4 25142.589 15.4 239* NSV11532 18525.643 14.6 25142.589 14.8 UCAC3162–217813 240 V358Sgr 18525.643 14.3 25142.589 15.2 241 NSV11649 18525.643 13.5 25142.589 15.4 2MASS19011546–1148397 242 V920Sgr 19980.642 <13.8 25127.587 12.7 243* CNAql 18525.643 12.1 25142.589 <14.0 244* V1940Sgr 19980.642 12.2 25127.587 14.5 245 EKSgr 18525.643 13.4 25142.589 14.6 246 V923Sgr 19980.642 <13.2 25127.587 12.9 247 V918Aql 18525.643 13.6 25142.589 <14.6 248 CUAql 18525.643 12.2 25142.589 <13.7 249* NSV11953 16676.835 13.2 25125.646 <15.7 2MASS19221196+2234390 250 DIAql 19980.642 <13.9 25127.587 12.3 251 XYVul 16676.835 12.9 25125.646 <14.5 252* V976Aql 17038.936 14.2 25174.566 <16.2 253 KUAql 17038.936 <15.5 25174.566 13.8 254 V1137Aql 17038.936 14.6 25174.566 15.4 255 CEVul 16676.835 13.5 25125.646 14.5: 256 V452Aql 17038.936 14.7 25174.566 <15.5 257 V453Aql 17038.936 <15.5 25174.566 15.1




258 LRAql 17038.936 14.5 25174.566 <15.9 259 V536Aql 17038.936 14.1 25174.566 15.5 260 V827Aql 17038.936 14.8 25174.566 <15.9 261 MUAql 17038.936 12.7 25174.566 14.4 262* DYAql 20427.606 11.8 25138.573 11.0 263 QXAql 19658.588 13.3 25127.663 <14.7 264 SZCap 20427.606 <15.2 25138.573 12.4 265 NSV12804 20427.606 14.0 25138.573 13.0 2MASS20071642–1315180 266 SSCap 20427.606 <16.0 25138.573 12.5 267 V581Aql 19658.588 13.2 25127.663 15.2 268 QYAql 17888.664 13.0 25142.704 11.2 269 STCap 20427.606 12.3 25138.573 <15.1 270 V586Aql 17888.664 13.0 25142.704 15.1 271* NSV12941 17888.664 14.2 25142.704 <15.6 2MASS20144760+1454058 272 V499Aql 20427.606 11.3 25138.573 12.1 273 RUDel 17888.664 15.2 25142.704 12.4 274 QZAql 17888.664 <14.8 25142.704 13.6 275* NSV13012 17888.664 13.1 25142.704 14.4 2MASS20200672+0805420 276 V335Aql 19658.588 12.1 25127.663 14.7 277 EPAql 18887.667 11.9 25175.551 <14.8 278 RWDel 17888.664 13.2 25142.704 14.5 279* NSV13086 17888.664 <14.7 25142.704 13.6 2MASS20263913+0852343 280 NSV13100 18887.667 16.4 25175.551 14.4 2MASS20284168–0531369 281 CQDel 17888.664 <16.1 25142.704 13.1 282 RYDel 17888.664 <15.5 25142.704 12.5 283 ETAql 18887.667 14.2 25175.551 12.2 284* V384Cyg 20387.639 14.9 25176.561 12.3: 285 BTAqr 18887.667 12.5 25175.551 11.7 286* LNCyg 20387.639 13.6 25176.561 13.7: 287* NSV13469 20387.639 13.7 25176.561 12.7: 2MASS21015589+3159129




288* DICyg 20387.639 12.6 25176.561 <13.7: 289 SXDel 18886.630 14.4 25128.597 13.1 290* GQCyg 20387.639 <15.1 25176.561 11.8: 291* V471Cyg 20387.639 12.9 25176.561 12.2: 292 ASPeg 18886.630 11.8 25128.597 15.5 293 APPeg 18886.630 12.3 25128.597 14.9 294 AYPeg 19713.684 14.9 25128.677 13.6*Notes:

R114: Marsden (2007) showed this suspected variable was not a minor planet observation.


R118: Probably not variable. Ross indicated a variation of two magnitudes between his two epochs, but we do not see a brightness change for the star he marked as the variable on his finding chart, nor for any nearby star, on these same plates.

R119: Probably not variable. The brightening detected by Ross on the 1909 plate taken with the 10-inch camera seems to result from a plate flaw—a dark smudge that does not look like a star image. No brightening was seen on the 6-inch plate. Ross (1926c) discussed plate flaws found on his plates in his paper that gave the proper motion stars detected in the R119 field.

R127: Ross published his fainter magnitude as 15 but his note card has 15(?). We do not believe the variable was seen but that Ross detected the close companions to the variable.

R130:Ross’publisheddeclinationhasa28'errorbuthisfindingchartandourre-examinationofthe plates confirm this identification.

R136: Bidelman and Cudworth (1981), Bedient (2003), and Marsden (2007) showed object seen in 1925 was a minor planet.


R148: This special case is discussed in the paper.


R164: The apparent variability is probably due to a plate flaw. The star image is brighter on the 1915 10-inch plate, but not on the 6-inch plate taken simultaneously.


R168: Marsden (2007) showed object seen in 1905 was a minor planet.

R184: Ross’ published magnitudes for the two epochs are reversed.


R194: Only Ross’ 10-inch plate could be located so we could not confirm the variability on the second plate set.

R200: Baumert and Cudworth (1981) identified this as the BL Lac object Ohio I 090.4.


R205: Date of second observation was 1927 Feb 1, not Feb 2 as published by Ross.




R206: Bedient (2003) and Marsden (2007) showed object seen in 1909 was a minor planet.

R207: Ross inverted the identifications of variable and comparison star on his finding chart.

R218: Marsden (2007) showed this object was not a minor planet observation. We found Ross’ published coordinates are in error. His finding chart and our re-examination of the plates confirm this identification.


R228: Ross’ published magnitudes for the two epochs are reversed.



R239: This star is very close to QT Sct, but a careful comparison of the finding chart for that object (Harwood 1960) with the field suggests R239 is not the same object as QT Sct.

R243:Ross’publisheddeclinationhasan11'errorbutre-examinationoftheplatesbybothBidelmanand van Altena (1972) and ourselves as well as the Ross finding chart confirm this identification.

R244: Ross’ published declination has a 2.3° error but his finding chart and our re-examination of the plates confirm this identification.


R252:Ross’publisheddeclinationhasa30'errorbuthisfindingchartandourre-examinationofthe plates confirm this identification.

R262:Ross’publishedpositionhasa21'errorbuthisfindingchartandourre-examinationoftheplates confirm this identification.


R275: The variable may be the star slightly north of our adopted identification.


R284: Ross’ published right ascension has a 21' error but his finding chart confirms thisidentification. The 1927 Oct 22 plates could not be located and the listed magnitude for this date is based on Ross’ estimate.

R286: The 1927 Oct 22 plates could not be located but Ross’ finding chart confirms this identification. The listed magnitude for this date is based on Ross’ estimate.

R287: The 1927 Oct 22 plates could not be located but Ross’ finding chart confirms this identification. The listed magnitude for this date is based on Ross’ estimate. The variability was confirmed on a 1922 Nov. 26 plate (JD 2,423,385.535) which gave a magnitude of 12.6.




Table1.IdentificationsandimproveddataforRossVariables105–294,cont. Notes (continued):


Table2.CorrectionstopublisheddatainpaperI,OsbornandMills(2011). Ross Corrected data

29 JDof15.0mag.observationis2418122.720;Ross’spublisheddate wasincorrect 66 StarisNSV11974 67 StarisNSV12000 72 StarisNSV12194 76 StarisNSV12573103 StarisNSV14720295 StarisNSV00670300 StarisNSV10725;opticaltransient(notX-ray)source ROTSE1J182240.62+293115.0303 StarisNSV11012317 StarisNSV12257368 StarisNSV06117

Appendix

Ross’snotecards forhisearlierdiscoveriescontainentries showing thatobservationsofsomeof thesuspectedvariablesweremadewith the40-inchrefractorbyhimorcollaborators.Thefollowingtablereproducesthesenotesverbatim, omitting the common note that the object might be an asteroid.A“v”referstothevariablewhileletters(a,b,m,n)refertocomparisonstarsthatareindicatedonthefindingcharts.Forthosecaseswhereavisualmagnitudeestimatewasmade,wefollowthereproducedcommentswiththeapproximateJulianDateoftheobservationandapproximateVmagnitude,derivedbyusingmodernmagnitudevaluesforthecomparisonstars.

TableA.Ross’snotesandderivedVmagnitudeestimates. Ross Comments on Ross’s note cards reproduced verbatim JD m(V)

114 1925Dec7: 40’’v=a=b(foundbySullivanonpl73)24492.6 12.9137 1926Nov10: Nothingbrighterthan16minthisplace 24830.6<16144 1926Nov10: b1mv1mm 24830.616:152 1926Nov10: invis.<16m 24830.6<16153 1926Nov10: v0.5mb 24830.6 12.1158 1926Nov10: vquitered!b3v2a 24830.6 12.0160 1926Nov10: m3v1n 24830.6 12.8

Terrell and Gross, JAAVSO Volume 40, 2012 941

GSC 4552-1643: a W UMa System With Complete Eclipses

Dirk TerrellDepartment of Space Studies, Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302; [email protected]

John GrossSonoita Research Observatory, 1442 E. Roger Road, Tucson, AZ 85719; [email protected]

Received October 6, 2011; revised October 17, 2011; accepted November 17, 2011

Abstract ObservationsandanalysisofGSC4552-1642arepresentedandthesystem is shown to be aW UMa system with complete eclipses.The total/annularnatureoftheeclipsesresultsinaphotometricmassratiothatshouldbereliablebutthelightcurvesdohaveappreciableamountsofthirdlight.

1. Background

GSC4552-1643islistedasstar828321intheGettel,et al.(2006;hereafterGGM)catalogueofovercontactbinarystarswithanorbitalperiodofabout0.27day.VisualinspectionofthelightcurvegivenbyGGMshowedthatitmighthavecompleteeclipses.Giventhegreatlystrengthenedanalysisthatcompleteeclipsescanprovide,webeganobservingthesystemwithJohnsonBandVandCousinsIfiltersattheSonoitaResearchObservatoryinSonoita,Arizona.Weused the20-inch telescopeequippedwithaSantaBarbara InstrumentGroupResearch STL 6303 CCD camera. Calibration (bias, dark, flat) and aperturephotometry were done with iraf. Observations were made on six nights inMarchandApril2011withatotalof283observationsintheBfilter,459inV, and436inI.GSC4552-0002wasusedas thecomparisonstarandGSC1399-0059wasthecheckstar.Theimageswerereducedusingiraftobiasanddark subtract the frames before flatfielding, and the calibration frames werecreatedbymedian-combiningatleasttwentyrawimages.Aperturephotometrywas performed on the images using the iraf phot package. Data from theAAVSO PhotometricAll-SkySurvey (APASS) (Hendenet al. 2010) for thestarsareshowninTable1.Thecomparisonminuscheckstarvaluesshowednovariabilitygreaterthan0.01magnitudeoverthecourseoftheobservingrun.

2. Analysis

Weanalyzedourobservationswiththemostrecentversionofthephoebeprogram (Prša and Zwitter 2005) which is based on the Wilson-Devinneyprogram(wd;WilsonandDevinney1971;Wilson1979).TheJ–Hvaluefrom

Terrell and Gross, JAAVSO Volume 40, 2012942

2MASS(Skrutskieet al.2006)is0.40±0.03,whichcorrespondstoaneffectivetemperatureofabout5600K(KenyonandHartmann1995).TheB–VvaluefromAPASSis0.78±0.08,correspondingtoatemperatureofaround5400K.SincetheJ–HandB–Vvaluesareingoodagreement,wesetthemeaneffectivetemperatureofstar1(thestareclipsedatprimaryminimum)equalto5500Kforthelightcurvesolution.Theadjustedparametersweretheorbitalinclination(i), themeaneffectivetemperatureofthesecondary(T2), themassratio(q),themodifiedsurfacepotentialofthecommonenvelope(–1),theheliocentricJuliandateoftheprimaryminimum(HJD0 ),theorbitalperiod(P),thebandpassluminosityoftheprimary(L1),andthirdlight(l3).Unadjustedparameterssuchasthegravitydarkeningexponents(g1,g2)andbolometricalbedos(A1,A2)wereset to their theoreticallyexpectedvalues for convectiveenvelopes (0.32and0.5,respectively).Thesquarerootlimbdarkeninglaw,usingtheVanHamme(1993)coefficients(x1,x2,y1,y2),gavethebestfitstothelightcurves.Weusedwd mode 3, appropriate for overcontact binaries of this type. The derivedparametervaluesareshowninTable2.Thethirdlightvaluesaretheratioofthethirdlightvaluetothetotalsystemlightatquadrature.Thefitshowsthattheslightlydeepereclipse(by0.01magnitudeinV)isthepartialone,technicallymakingthisanA-typesystem,butthelightcurveclearlyshowsasymmetriesandlargescatter,sowecannotmakethatclassificationwithhighconfidence.Figure1showsthefitstotheobservations. In W UMa systems like this, there is an astrophysical interest in thetemperaturedifferenceofthetwocomponents.Theprimarystar’stemperatureisestimatedfromtheobservedB–VandJ–Hcolorswithanapproximateerrorof200Kfromtheobservationalerrorsofthecolors.ThelightcurvesolutiongivestheerrorinT2,giventheassumedT1fromtheobservedcolors.ThusthetrueuncertaintyinT2issimilartotheuncertaintyinT1.However,theuncertaintyinthetemperaturedifference,T2–T1,issimilartotheformalsolutionerrorinT2sinceT1isassumedtobefixed.Toillustratethis,were-didthelightcurveanalysiswithT1=5700KandfoundT2=5858K,foratemperaturedifferenceof158K,comparedtoavalueof152KforthesolutioninTable1.So,whiletheindividualtemperaturesareuncertainatthelevelof200K,theuncertaintyintheirdifferenceismuchsmaller,oforder10–20K.

3. Conclusions

Because of its total/annular eclipses and overcontact configuration, wemight expect the photometric mass ratio to be well-determined (Terrell andWilson2005).However,TerrellandWilson(2005)didnotconsidertheeffectofthirdlightonthemassratiodetermination.Thissystemshowsappreciablethirdlight,withthefluxfromthethirdbodycomparabletothatofthesecondarystaratquadrature.SimulationslikethoseofTerrellandWilson(2005)areunderwaytodeterminehow third lightmight affect their findings, althoughwedonot

Terrell and Gross, JAAVSO Volume 40, 2012 943

References

Gettel,S.J.,Geske,M.T.,andMcKay,T.A.2006,Astron. J.,131,621.Henden,A.A.,Terrell,D.,Welch,D.,andSmith,T.C.2010,Bull. American

Astron. Soc.,42,515.Kenyon,S.J.,andHartmann,L.1995,Astrophys. J., Suppl. Ser.,101,117.Prša,A.,andZwitter,T.2005,Astrophys. J.,628,426.Skrutskie,M.F.,et al.2006,Astron. J.,131,1163.Terrell,D.,andWilson,R.E.2005,Astrophys. Space Sci.,296,221.VanHamme,W.1993,Astron. J.,106,2096.Wilson,R.E.1979,Astrophys.J.,234,1054.Wilson,R.E.,andDevinney,E.J.1971,Astrophys. J.,166,605.

expectittohavealargeeffectonthemassratiodetermination.AsdiscussedbyTerrellandWilson(2005),thephotometricmassratioforatotallyeclipsingovercontactsystemisaccuratebecauseofthehighaccuracytowhichtheratioof the stellar radii canbedetermined.Since third light affects thedepthsofbotheclipses,ratherthanoneortheotherstrongly,wedonotexpecttheratiooftheradiitobestronglyaffected,andthephotometricmassratioshouldbereasonably accurate.The luminosity ratio in this system is, however, not soextremeas topreclude the ability tomeasure a spectroscopicmass ratio, sothissystemcouldhaveitsabsolutedimensionsdeterminedaccuratelybecauseof thecompleteeclipses,even if thephotometricmass ratioshouldprove tobeinaccurateduetothirdlightissues.Aspectroscopicstudyofthissystemissorelyneeded.

Table1.Colorsofthevariable,comparison,andcheckstars. Star B–V

Variable GSC4552-1643 0.78±0.08 Comparison GSC4552-0002 0.92±0.08 Check GSC4552-0059 0.50±0.06

Terrell and Gross, JAAVSO Volume 40, 2012944

Table2.Parametersforthelightcurvesolution.*

Parameter Value

i 88.9±0.6° T2 5652±10K q 0.327±0.004 Ω1 2.435±0.008 HJD0 2452500.187±0.002 P 0.2698999±0.0000001day L1/(L1+L2)B 0.687±0.010 L1/(L1+L2)V 0.697±0.009 L1/(L1+L2)I 0.705±0.009 l3B 0.163±0.008 l3V 0.185±0.007 l3I 0.212±0.008 A1,A2 0.5(fixed) g1,g2 0.32(fixed) x1,y1(Bfilter) 0.77,0.09(fixed) x1,y1(Vfilter) 0.46,0.35(fixed) x1,y1(Ifilter) 0.19,0.48(fixed) x2,y2(Bfilter) 0.72,0.14(fixed) x2,y2(Vfilter) 0.43,0.37(fixed) x2,y2(Ifilter) 0.18,0.48(fixed)* The quoted errors are the formal errors from the differential corrections solution. Since the primary star’ s temperature is estimated from the observed B–V and J–H colors with an approximate error of 200 K; the secondary star’ s uncertainty in temperature is similar. The formal error is more indicative of the precision to which the solution can fit the ratio of the stellar temperatures, rather than the absolute temperatures.

Figure1.BVI lightcurvesofGSC4552-1643and the fits fromtheWilson-DevinneysolutiongiveninTable2.

Damassoetal., JAAVSO Volume 40, 2012 945

VSX J071108.7+695227: a Newly Discovered Short-period Eclipsing Binary

Mario DamassoAstronomical Observatory of the Autonomous Region of the Aosta Valley, fraz. Lignan 39, 11020 Nus (Aosta), Italy; INAF associated; [email protected] and [email protected]

and

Dept. of Physics and Astronomy, University of Padova, vicolo dell’Osservatorio 3, I-35122 Padova, Italy

Davide CenadelliPaolo CalcideseAstronomical Observatory of the Autonomous Region of the Aosta Valley, fraz. Lignan 39, 11020 Nus (Aosta), Italy; INAF associated

Luca BorsatoDept. of Physics and Astronomy, University of Padova, vicolo dell’Osservatorio 3, I-35122 Padova, Italy; INAF-OAPd associated

Valentina GranataDept. of Physics and Astronomy, University of Padova, vicolo dell’Osservatorio 3, I-35122 Padova, Italy

Valerio NascimbeniDept. of Physics and Astronomy, University of Padova, vicolo dell’Osservatorio 3, I-35122 Padova, Italy; INAF-OAPd associated

Received March 28, 2012; revised April 13, 2012; accepted April 16, 2012

Abstract WereportthediscoveryofanEWvariable,VSXJ071108.7+695227,withashortorbitalperiodof~0.238day.Thisperiodisveryclosetothelowerlimitof~0.22daythathasbeenfoundforEWsystems.Herewepresentanddiscuss photometric and spectroscopic data of the variable, collected at theAstronomicalObservatoryoftheAutonomousRegionoftheAostaValleyandattheAsiagoAstrophysicalObservatory.ThelightcurvesshowsomeasymmetriesandthespectrasuggestadK4classificationforthetwocomponents.Itcouldbeinterestingtocarryoutfurtherobservationsofthissystematdifferentepochsbecausesuchsystemsfrequentlyshowvariationsinperiodandinthefeaturesofthelightcurve.

Damassoetal., JAAVSO Volume 40, 2012946

1. Introduction

We report the discovery of VSX J071108.7+695227 (= 2MASSJ07110876+6952276), a short-periodeclipsingbinary system.Weclassify it as anEWtypevariable.Thisvariable, located in theconstellationCamelopardalis(R.A. 07h 11m 08.76s; Dec. +69° 52' 27.6"; epoch J2000.0), was discoveredthankstophotometricobservationsperformedattheAstronomicalObservatoryof theAutonomousRegionof theAostaValley (OAVdA),andat theAsiagoObservatory.Thesystemhasanestimatedorbitalperiodof~0.238day. The variable deserves further investigation mostly because the assessedperiod is very short and pretty close to the sharp cut-off at the lower limitof~0.22dayfoundbyNortonet al. (2011) for thesebinaries.Onlyaminorpercentage of EW variables have periods shorter than ours. For example,Rucinski (2006) found thatonlya few tensoutof the4,638EWsystemsoftheASASsamplehaveaperiodshorterthanorsimilartoours,Weldrakeet al.(2007)foundonlytwooutoffifty-eightshortperiodeclipsingbinariestohaveP<0.238day,andMilleret al.(2010)abouttenoutof533.Todate,thelargestsampleofEWsystemswithaperiodshorterthanoursismadeupofthefifty-threeEWbinarieswithP<0.2314daylistedbyNortonet al.(2011).Moreover,suchclosesystemsshowseveralfeaturesthatchangeovertime,astheorbitalperiodandtheshapeofthelightcurves,aswediscussbelow. Allthisconsidered,wepursuedaphotometricandspectroscopicanalysisofourvariableaimedatbettercharacterizingitsphysicalproperties.WedeterminedB,V,andRlightcurves,weassignedthetwocomponentstoaspectraltype,welookedforpossibleactivityindicatorsinthespectralikeemissionlines,andwesoughtasymmetriesinthelightcurves.

2. Instrumentation and methodology

Sincetheendof2008,attheOAVdAisunderwaytheimplementationofan extensiveobservational campaignaimedat finding small-sizedextrasolarplanetsaroundMdwarfsusingthephotometrictransitmethod(Damassoet al.2010;Giacobbeet al.2012).ThefirstobservationsofVSXJ071108.7+695227wereperfomedattheendofDecember2011,duringthecommissioningtestsofthenewtelescopearraywhichwillbeusedforafive-yearsurveyofhundredsofMdwarfsinthesolarneighborhood.Thearrayiscomposedoffouridentical40-cm f /8.4 Ritchey-Chrétien telescopes, each on a 10 MICRON QCI2000mountandequippedwithaFLIProLine1001ECCDcamera. After the discovery, we photometrically followed up on the binarysystemwiththemaintelescopepresentinOAVdA,an81-cmf/7.9Ritchey-Chrétiencoupledtoaback-illuminatedCCDcameraFLIProLinePL3041-BBandstandardBVRIfilters.Thesensoris2048px×2048px,withapixelarea of 15 × 15 μm2.The system has a FoV of 16.5×16.5 arcmin2 with a


platescaleof0.48"/pixel(binning1×1).Wepresentanddiscusshere thedatacollectedwiththistelescope.InFigure1wepresentoneofourframesandindicateoursystem.

2.1.Photometricdata Thescientificframestakenduringthediscoverynightandthefollow-upobservations were reduced and analyzed with the software package teepee(Transiting ExoplanEts PipElinE) developed by some of the authors. Adetaileddescriptionofthebasicfunctionsoftheteepeepipelineisprovidedin Damasso et al. (2010). In short, the final result of the data processingis thegenerationof thedifferential light curvesof all the stars in theCCDfieldwhichwereautomaticallyrecognizedineveryframeoftheseries.Theensemblephotometryisobtainedtestinguptotwelveapertures.Thebestsetofcomparisonstarsisautomaticallydeterminedforapre-selectedtargetfromalistofthe100brightestobjectsfoundinthefield,excludingtheonestooclosetotheCCDborders.TheapertureandsetofreferencestarsselectedattheendofthedataprocessingaretheoneswhichgivethesmallestRMSfortheentirelightcurveoftheobjectofinterest. Figure2 (a,b, c) shows thenormalizeddifferential lightcurvesofVSXJ071108.7+695227obtainedinB,V,andRfiltersonJanuary16,2012,duringthefollow-upobservationswiththe81-cmtelescope.Thedifferentialmagnitudesarecalculatedasthedifferencebetweentheaverageinstrumentalmagnitudesofthecomparisonstarsandtheinstrumentalmagnitudesofthevariablestar.ThecomparisonstarsautomaticallyselectedbytheteepeepipelineforeachfilterarelistedinTable2.ThelightcurvesclearlyunveiltheEWvariabilitytypefortheobjectandtheobservationscoveralmost1.75timestheorbitalperiodofthetwocomponentsofthesystem,whichweestimatedtobe~0.238dayusingtheFastChi-SquaredalgorithmdescribedinPalmer(2009)andfreelyavailableat http://public.lanl.gov/palmer/fastchi.html. Figure 3 shows the normalizedV-band lightcurve foldedaccording to theorbitalperiod.Thezeroepoch isHJD(0)=2455943.438. We estimate a mean V magnitude for the object through the relationsdescribed inPavlov(2009),whichuse theJ–Kcolor indexfromthe2MASScatalogue(Skrutskieet al.2006)andtheUfandUamagnitudesfromtheUCAC-3catalogue(USNO2012):

Vf=0.531·(J–K) + 0.906·Uf + 0.95±0.08 (1)

Va=0.529·(J–K) + 0.9166·Ua + 0.83±0.08 (2)

Averagingthetwovaluesfoundfrom(1)and(2)resultsinV=14.37,whereJ=12.631,K=11.923,Uf=14.366,andUa=14.396. UsingthefollowingconversionrelationsbetweentheUSNO A2.0(Monetet al.1998)andLandoltBRmagnitudes(Kidger2003):


B=1.097·USNO(B) – 1.216 (3)

R=1.031·USNO(R) – 0.417 (4)

whereUSNO(B)=14.8andUSNO(R)=13.9,weobtainedB=15.0andR=13.9. Moreover, thestaralsoappears in theAPASScatalogue(AAVSO2012),which provides other estimates for B and V magnitudes: B=15.485±0.368;V=14.468±0.289.

2.2.Spectroscopicdata Tobettercharacterizethevariableandlookforpossibleactivityindicatorslike emission lines, on January 26, 2012, we took nine consecutive spectrawiththe182-cmCopernicotelescopeattheAsiagoObservatory(http://www.pd.astro.it/asiago/), using the AFOSC CCD camera. Two different opticalconfigurations were used (grism3 and grism8) with different dispersion andspectralcoverage.ThemainfeaturesoftheseconfigurationsaresummarizedinTable1.Wetookfivespectrausingthegrism3andfourwiththegrism8. InFigure3weoverplotted(solidanddashed)verticallinescorrespondingtotheorbitalphasesatwhichtheninespectraofthesystemwerecollected.Itcanbeseenthatthefirstones(withbothconfigurations)weretakenatmaximumbrightness.TheyareshowninFigure4.Theotherspectradonotshowsizeabledifferencesascomparedtothese,atleastatthelowdispersionaccessibletous.Itcanbenoticed,however,thattheyweretakenatanotverydifferentphase.3. Discussion

At theepochofourobservationsthelightcurvesof thevariableshowedsomeclearasymmetries,asexpectedfromsuchshort-periodsystems.ThemostsignificantisanevidentO’ConnellEffectasthemagnitudeofthetwomaximaisdifferent (DavidgeandMilone1984).Theconventionalway toassess thesizeofthiseffectistomeasurethepeakmagnitudeaftertheprimary(deepest)minimumsubtractedfromthepeakmagnitudeafterthesecondaryminimum.From Figure 2 we derive that ΔB ~ ΔV ~ ΔR~+0.05.Furthermore,acloserinspectionoftheBcurverevealsasmall“shoulder”alongtherisetowardsboththesecondarymaxima.Thisispossiblyduetotheocurrenceofstarspots. Infact,itiswell-knownthatthatEWvariablesareusuallyheavilyspottedsystems,astheoreticallypredictedbyBinnendijk(1970).Hewasthefirsttopropose that dark spots exist on the surfaces of the components to explainthe asymmetry and variability of the light curves at different epochs. Thishypothesis was later demonstrated by Doppler imaging (see for instanceHendryandMochnacki2000).OneoftheauthorsofthepresentpaperalreadydealtwiththisissueanddetectedthepresenceofstarspotsinlightcurvestakenatdifferentepochsofoneEWvariablewithanorbitalperiodof~0.355day(Damassoet al.2011).


Starspotsareapossibleexplanationof theO’ConnellEffectaswell,butthereismuchuncertaintyinthisrespect(WilseyandBeaky2009). Itwouldbeinterestingtocollectnewdataofthissystematdifferentepochstoputinevidencepossibleevolutionsthatourdata,takenduringasinglenight,cannotreveal.Inparticular,short-periodsystemslikeourscanshowvariationsinperiodorintheshapeofthelightcurves,likeaninversionoftheprimaryandsecondarymaximaleadingtoanO’ConnellEffectwithoppositesign(seeforexamplethecaseofV523CastreatedinZhangandZhang2004). Letusnowturntothediscussionofthespectroscopicdata.ThespectrainFigure4displaythetypicalshapeofKstars,withoutanyevidentsuperpositionof different spectral types.This suggests that both components have similarspectraandsurfacetemperatures.Thisisinaccordancewiththefactthattheminimainthelightcurvesarealmostequalindeepness. WUMabinariesareexpectedtobelocatedwithinorinproximityofthemainsequencestars(Biliret al.2005).Thiscanbeconfirmedbyourspectra:theprominenceoftheMgHbandaround5200Åandthetooth-shapedMgHfeature around 4770Å strongly suggest that the stars are dwarfs (Gray andCorbally2009,p.262). Toobtainamorepreciseclassification,weresortedtothelineshighlightedinFigure4(c):theCaIlineat6162Å,theBaII-FeI-CaIblendat6497Å,andtheHα line at 6563 Å. The latter directly correlates with temperature, while the first twoinverselycorrelatewithtemperature,sothattheCaIorBaII-FeI-CaIblendto Hα ratio is a useful temperature indicator. Althoughinlate-typestarsitisoftendifficulttospotoutanactualcontinuumtoreferto,wecalculatedtheequivalentwidthsofthesethreelineswhichareonlyindicative.Theyare:

Wλ (CaI) = 1.7ÅWλ (blend) = 0.8ÅWλ (Hα) = 0.4Å

WedecidedtocompareourspectratotheonestabulatedbyAllenandStrom(1995)becausetheypossessaspectralcoverageandresolutionquitesimilartoours. The CaI to Hα ratio suggest a dK4 classification. Afurtherclueastohowtoclassifythetwostarscanbegivenbytheslightdifferenceindepthofthetwominima.Suchdifferenceisnearlyequalto0.05magnitude,thatis,~4.7%influx.CallingT1,2thesurfacetemperaturesofthetwocomponentswecanroughlyinferthat(T1/T2)

4 ~1.047 → T1/T2~1.012,thatis,thecomponent1ishotterthanthecomponent2by1.2%.Attemperaturesbetween 4000 and 5000K this means a difference of ~50K. Unfortunately,thesurfacetemperatureoflowermainsequencestarsisnoteasytocalculateandwithina samespectral type therecanbeavarianceofmore than100K(seeforexampleCasagrandeet al.2006).Hence, thecalculated temperature


differencecannotbesafelyassumedastotestifyadifferenceofspectraltypebetweenthetwocomponents.Intheend,werestuponadK4classificationforbothcomponents.Inaddition,thisconclusionisconsistentwithaclassificationbasedonthecolorindices:accordingtoCox(2000)adK4starisexpectedtohaveJ–H=0.58andH–K=0.11,andourvariablehasJ–H=0.583andH–K=0.125. Furthermore,wecantrytodeducethemassesofthetwostars.Ifwecallatheoverallsemi-majoraxisofthesystem(thatis,thesumofthetwosemi-majoraxeswithrespecttothecenterofmass)expressedinAUs,Ttheperiodexpressed inyears,andM1,2 themassesof the twocomponentsexpressed insolarunits,wehave:

a3=T2(M1+M2) (5)

FromourphotometricdatawededuceT=0.238day=6.516×10–4yr.Amid-KdwarftypicallyhasamassM~0.7–0.75;assumingM1+M2=1.45,itresultsthata~1.27×106km. AssumingbothcomponentstohavearadiusR

0.75–0.8withrespecttothe

Sun,thatis,about5×105km,wehavea~2.5R.ThisisfinebecauseWUMavariablesaresupposedtobealmosttouchingeachother. Moreover,onecouldaskhowlargeaDopplerbroadeningsuchanorbitalpatternwouldentailinspectra.Letusassumeacircularorbit.AtthetimeofmaximuminthelightcurveweshouldhaveanoverallDopplerbroadeningoftheorderof:

Δλ / λ = v / c = 2πa / (Tc)=1.29×10–3 (6)

If we consider the Hα line at 6563Å we have that Δλ ~ 8 Å, that is, the widthofthelineshouldextendaboutfrom6554.5to6571.5Å.Ifweconsiderthe CaI line at 6162 we have Δλ 8Å, that is, the width of the line should extend aboutfrom6154to6170Å.Thesevaluesareconsistentwithourspectra,butbecauseofthelowdispersionwecanattainwebelievewecannotdrawanysureconclusioninthisrespect. Wefinallylookedforpossibleactivityindicatorsinthespectralikeemissionlines,butwefoundnoneatthelevelofresolutionaccessibletous.

4. Acknowledgements

AuthorsDamasso,Cenadelli,andCalcidesearesupportedbygrantsprovidedbytheEuropeanUnion,theAutonomousRegionoftheAostaValleyandtheItalianDepartmentforWork,HealthandPensions.TheOAVdAissupportedbytheRegionalGovernmentoftheAostaValley,theTownMunicipalityofNusandtheMontEmiliusCommunity.ThetelescopewhichledtothediscoveryofthevariablestarhasbeenfundedbytheFondazioneCassadiRisparmiodiTorino(CRT).This


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373,13.Cox, A. N. 2000, Allen’s Astrophysical Quantities, 4th ed., Springer, New

York.Damasso,M.,et al.2010,Publ. Astron. Soc. Pacific,122,1077.Damasso,M.,et al.2011,Open Eur. J. Var. Stars,No.138,1.Davidge,T.J.,andMilone,E.F.1984,Astrophys. J., Suppl. Ser.,55,571.Giacobbe,P.,et al.2012,Mon. Not. Roy. Astron. Soc.,424,3101.Gray,R.O.,andCorbally,C.J.2009,Stellar Spectral Classification,Princeton

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standardLandoltBVRmagnitudes”(http://quasars.org/docs/USNO_Landolt.htm,accessedApril2012).

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hristopavlov.net/Articles/index.html).Rucinski,S.M.2006,Mon. Not. Roy. Astron. Soc.,368,1319.Skrutskie,M.F.,et al.2006,The Two Micron All Sky Survey, Astron. J., 131,

1163.U.S. Naval Observatory. 2012, UCAC-3 (http://www.usno.navy.mil/USNO/

astrometry/optical-IR-prod/ucac).Weldrake,D.T.F.,Sackett,P.D.,andBridges,T.J.2007,Astron. J.,133,1447.Wilsey,N.J.,andBeaky,M.M.2009,inThe Society for Astronomical Sciences

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researchhasmadeuseoftheSIMBADdatabase,operatedatCDS,Strasbourg,France,andof theNASAAstrophysicsDataSystemBibliographicServices.


Table2.ComparisonstarsusedfordifferentialphotometryinB,V,andRbands. Star R.A. Dec. Band h m s ° ' ''

UCAC-3320-037770 070919.041 +695506.66 B V UCAC-3320-037772 070921.093 +695600.27 B UCAC-3320-037776 070924.095 +695659.02 B V R UCAC-3320-037779 070928.970 +695143.34 B R UCAC-3320-037783 070932.398 +695057.44 B UCAC-3320-037784 070932.649 +695842.06 B UCAC-3320-037787 070934.315 +694949.11 B V R UCAC-3320-037794 070942.534 +695059.13 B UCAC-3320-037795 070943.173 +695442.21 B UCAC-3320-037798 070945.939 +695515.41 B UCAC-3320-037799 070947.551 +695226.48 B UCAC-3320-037820 071009.948 +695517.80 B UCAC-3320-037821 071011.189 +695045.90 B UCAC-3320-037823 071014.455 +695034.28 R UCAC-3320-037827 071020.912 +694940.04 B V R UCAC-3320-037828 071021.806 +695230.72 B UCAC-3320-037831 071023.959 +695124.78 B R UCAC-3320-037835 071031.401 +695352.17 B UCAC-3320-037849 071038.339 +695718.61 B UCAC-3320-037857 071042.666 +694914.61 B UCAC-3320-037860 071044.576 +695152.55 B UCAC-3320-037862 071047.011 +695135.23 B UCAC-3320-037867 071054.909 +695217.17 B V R UCAC-3320-037871 071103.636 +695231.88 B UCAC-3320-037876 071107.800 +695127.49 B V UCAC-3320-037881 071110.879 +695129.52 B V UCAC-3320-037885 071114.572 +695607.65 B V R UCAC-3320-037896 071127.544 +694808.74 B UCAC-3320-037901 071132.558 +695203.82 B V R 2MASS07110649+6947296 071106.492 +694729.61 B 2MASS07094405+6952413 070944.051 +695241.40 B

Table1.Opticalconfigurationsusedtoacquirethespectraofthevariable. Configuration Spectral coverage Mean dispersion Resolution

grism3 ~3700–~5850Å ~2.1Å/px ~650 grism8 ~5950–~8000Å ~2.0Å/px ~1900


Figure1.ThestarfieldofVSXJ071108.7+695227,withthevariablestartargethighlighted.Thescaleoftheimageis16.5×16.5arcmin2.Northisupandeastistotheleft.

Figure2a.DifferentiallightcurveofthevariablestarVSXJ071108.7+695227inBfilter.ThedatawerecollectedonJanuary16,2012.

Figure2b.DifferentiallightcurveofthevariablestarVSXJ071108.7+695227inVfilter.ThedatawerecollectedonJanuary16,2012.

Figure2c.DifferentiallightcurveofthevariablestarVSXJ071108.7+695227inRfilter.ThedatawerecollectedonJanuary16,2012.


Figure3.DifferentiallightcurveofVSXJ071108.7+695227inVbandfoldedaccordingtotheorbitalperiod~0.238days.

Figure4a.SpectraofthevariablestarVSXJ071108.7+695227atmaximumbrightness,takenwithgrism3.ThemidepochoftheexposureisHJD2455953.493615.

Figure4b.SpectraofthevariablestarVSXJ071108.7+695227atmaximumbrightness,takenwithgrism8.AmagnifiedregionisdisplayedinFigure4c.ThemidepochoftheexposureisHJD2455953.497677.

Figure4c.AmagnifiedregionofthespectraofthevariablestarVSXJ071108.7+695227atmaximumbrightness,takenwithgrism8.ThemidepochoftheexposureisHJD2455953.497677.

Furgoni, JAAVSO Volume 40, 2012 955

Variability Type Determination and High Precision Ephemeris for NSVS 7606408

Riccardo FurgoniKeyhole Observatory, Via Fossamana 86, S. Giorgio di Mantova (MN), Italy; [email protected] Astrofili Mantovani—Gorgo Astronomical Observatory MPC 434, S. Benedetto Po (MN), Italy

Received May 11, 2012; revised June 4, 2012; accepted June 14, 2012

Abstract Aphotometric campaignanalysisof the starNSVS7606408hasbeenconductedinordertodeterminethetypeofvariabilityandhighaccuracyephemeris.Bycombiningtheobtaineddatawithotherdatasetsavailable,itwastriedtoimprovethedeterminationoftheperiod,highlighting,however,apossibleminimalchangeoftheperiodovertheyears.AtMay2,2012,theephemeriscalculated for this variable star is HJDmin = (2456015.44998±1.1×10–4)+E×(0.35482573±3×10–8)+E2×(2.4×10–10±1×10–11)

1. Introduction

In recent years many wide field photometric surveys have led to thediscoveryofalargenumberofvariablestarsofdifferenttypes.Theseinclude:NSVS (Northern SkyVariability Survey—an extensive variability survey ofthe sky north of Dec. −38˚ with daily time-sampling and a one-year baseline, by the Los Alamos National Laboratory; SuperWASP (Wide Angle Searchfor Planets)—UK’s leading extra-solar planet detection program comprisingaconsortiumofeightacademicinstitutions,includingCambridgeUniversity,theInstitutodeAstrofisicadeCanarias,theIsaacNewtonGroupoftelescopes,Keele University, Leicester University, the Open University, Queen’sUniversityBelfast, andSt.Andrew’sUniversity;ASAS (AllSkyAutomatedSurvey)—alow-costprojectdedicatedtoconstantphotometricmonitoringofthewholeavailable sky,which isapproximately107 starsbrighter than14thmagnitude—the project’s ultimate goal is detection and investigation of anykindofphotometricvariability.Despitethis,therehasneverbeenmadeaprecisestudyofmanyofthemwiththeaimofdeterminingtheclassofvariabilityandobtainingphaseplotswithareasonablylowscattering.Mostoftheinstrumentsdedicatedtolarge-scaleresearchuseshortfocallengthtelescopeswhichgiveextremelycrowdedimagesofstarfields,makingthephotometricmeasurementsdifficultandsometimesinaccurate.Thedatabasesgeneratedbythesesurveys,however,areaparticularlyvaluablesourceofdatainobtainingconfirmations

Furgoni, JAAVSO Volume 40, 2012956

ofnewlydiscoveredvariablestarsandinallowingaprecisedeterminationoftheperiodsofregularvariables.Havingdataconcerningalargeperiodoftimemakesperioddeterminationmuchmoreeffective.

2. Instrumentation used

The data were obtained with a Celestron C8 Starbright, a Schmidt-Cassegrain optical configuration with aperture of 203mm and centralobstructionof34%. Thetelescopewaspositionedatcoordinates:45°12'32''N10°50'20''E(WGS84),inaruralareawithlowtomediumlightpollution.ThetelescopewasequippedwithafocalreducerBaaderPlanetariumAlanGeeIIabletobringthefocallengthfrom2030mmto1396mm.Thefocalratiowasreducedtof /6.38fromtheoriginalf /10. Thepointingwasmaintainedwith aSynthaNEQ6mountwith softwaresynscan3.27guidedthroughaBaaderVarioFindertelescopeequippedwithaBarlowlenscapableofbringingthefocallengthofthesystemto636mmandfocalratiooff /10.5. The guide camera has been a Magzero MZ-5 with Micron MT9M001monochromesensorequippedwithanarrayof1280×1024pixels.Thesizeofthe pixels is 5.2 μm × 5.2 μm for a resulting sampling of 1.68 arcsec/pixel. The CCD camera has been a SBIG ST8300m with monochrome sensorKodakKAF8300equippedwithanarrayof3352×2532pixels.Thepixelsareprovidedwithmicrolensesforimprovingthequantumefficiency,andthesizeof the pixels is 5.4 μm × 5.4 μm for a resulting sampling of 0.80 arcsec/pixel. Thecamerahasaresolutionof16bitswithagainof0.37e-/ADUandafull-well capacity of 25,500 electrons. The dark current is 0.02e-/pixel/sec at atemperatureof–15°C.Thetypicalreadnoiseis9.3e-RMS. Thecameraisequippedwith1,000×antiblooming:afterexhaustivetestingithasbeenverifiedthatthezoneoflinearresponseisbetween1,000and20,000ADU,althoughatupto60,000ADUthelossoflinearityislessthan5%.TheCCD is equipped with a single-stage Peltier cell ΔT = 35 ± 0.1° C which allows coolingatastationarytemperature.

3. Data collection

TheobservationswereperformedwiththeCCDatatemperatureof–5°Cinbinning1×1.Theexposuretimewas55secondswithadelayof1secondbetweentheimagesandanaveragedownloadtimeof11secondsperframe.Thestarhasbeenobservedwithamaximumpixelintensityofabout3,400ADUandSNR80.Thecomparisonstarhadpixelswithmaximumintensityofabout4,000ADUandSNR100.Thecheckstarhadpixelswithmaximumintensityofabout4,200ADUandSNR110.AllstarshaveADUintensitywithintheregionoflinearresponseoftheCCD.


Theobservationswere carriedoutwithout theuseofphotometric filterstomaximizethesignal-to-noiseratio.ThespectralsensitivityoftheCCD,asshowninFigure1, ismaximumatawavelengthof540nm,makingthedatamorecompatiblewithamagnitudeCV(ClearFilter—ZeroPointV). TheobservationswereconductedovereightnightsaspresentedinTable1. TheCCDcontrolprogramwasSoftwareBisque’sccd softv5.Once theimageswereobtained,calibrationframesweretakenforatotalof30darkof55secat–5°C,80darkflatof2secat–5°C,and100flatof2secat–5°C.Thedarkflatsanddarksweretakenonlythefirstobservationsessionandusedforallothersessions.TheflatswereperformedforeachsessionasthepositionoftheCCDcameracouldbevariedslightly,aswellasthefocuspoint. Thecalibrationframeswerecombinedwiththemethodofthemedianandthe masterframes obtained were then used for the correction of the imagestaken.AllimageswerethenalignedandanastrometricreductionwasmadetoimplementtheastrometricalcoordinatesystemWCSintheFITSheader.Theseoperationswereconductedentirelythroughtheuseofsoftwaremaximdl v5.18madebyDiffractionLimited.

4. The measurement of NSVS 7606408

ThestartobemeasuredwasobservedwithintheNorthernSkyVariabilitySurvey(NSVS;Wozniaket al.2004),whichisaphotometricsurveyforstarswithanopticalmagnitudebetween8and15.5.The researchwasconductedduringthefirstgenerationoftheRoboticOpticalTransientSearchExperiment(ROTSE-I) using a robotic system composed by four photographic lenseswithoutphotometric filtersconnected toCCDs.The researchwasconductedbyLosAlamosNationalLaboratory(NewMexico)inordertocovertheentirenorthernhemisphereofthesky.Inayearofworkbetween1999and2000anaverageof150photometricmeasurementsfor14millionstarswasmade. At the end of this research an automatically extended data analysis wasmadethatledtothediscoveryofvariablestellarsources.NSVS7606408hasbeen recognized as a source with confirmed variability (Shaw et al. 2009).Identificationdataforthisstarareasfollows:

Name: NSVS7606408

Position(UCAC3): R.A.(2000),11h48m56.586s, Dec.(2000)+26°02'30.07"

CrossIdentifications: GSC2.2N201201146 CMC14114856.5+260230 USNO-B1.01160-0187403 NOMAD11160-0192011 PPMX114856.5+260230


UCAC3233-104554 2MASSJ11485658+2602301 SDSSJ114856.58+260229.9

Propermotion(PPMX):pmR.A.=–0.08mas/yr;pmDec.=2.39mas/yr

AAVSOVSXperiod: 0.17740547day(fromShawet al.2009)

ThestarfieldcontainingthevariablestarisshowninFigure2. Thestar’sbrightnesswasmeasuredwithmaximdl v5.18software,usingtheapertureringmethod.WithaFWHMoftheobservingsessionsattimesarrivedatvaluesof5"itwasdecidedtochoosevaluesprovidinganadequatesignal-to-noiseratioandthecertaintyofbeingabletoproperlycontainthewholefluxsentfromthestar.Ihaveusedthefollowingapertures:

Apertureradius,12pixels;Gapwidth,2pixels;Annulusthickness,8pixels

Thechoiceofmakingobservationswithouttheuseofphotometricfiltersrequiredaproperstudyofthefieldinordertoidentifycomparisonstarswithcolor similar to the variable under study, and with adequate signal-to-noiseratio,toobtainasaccuratedifferentialphotometryaspossible. Thechoicewasmadebyanalyzing themeasures relating tophotometric2MASS(Skrutskieet al.2006)bandsJ,H,andKasmentionedintheCarlsberg Meridian Catalog 14 (CMC14; Copenhagen Univ. Obs. et al. 2006). In theabsenceofprecisemeasuresofthemagnitudeinthestandardVJohnson-Cousins,forstarsusedintheanalysisitwasdecidedtoderivetheirVmagnitudefromthecatalogCMC14r'magnitudeasdescribedinDymockandMiles(2009).Thiswayensuresagoodreliabilityandafinalerrortheoreticallynotmorethan0.05magnitudeinV.Theconversionformulaisasfollows:

VJohnson-Cousins=0.6278×(J2MASS–K2MASS)+0.9947×r'CMC14(9<r'<16) (1)

Thepossiblespectral typehasbeenderivedfromthe2MASSJ–Hvalueinstead, as shown in CMC14. The method is described in Stead and Hoare(2002)withtheresultsasshowninTable2. Withinthestarfieldanalyzed,onlytwostarshaveanadequatesignal-to-noise ratioandcolor similar to thevariableunder study.TheirpositionwithrespecttothevariableisshowninTable3andFigure3. ThroughdifferentialphotometrytheaveragemagnitudeofNSVS7606408is13.572±0.006CVdeterminedbyplacingthecomparisonstar’smagnitudeat13.325CV.WhereasthevariabilityofthestarisbyfarsuperiortothegapthatthisvaluehaswiththeVmagnitudederivedfromCMC14(=13.641),itcanbeconsideredanacceptableresult.Themeanmagnitudeerrorforallthesessionsis0.006CV.Forthelongestobservingsessionthelightcurvesofthe


variablestarandthecheckstarinrelationtothecomparisonstarareshowninFigure4. The check star shows an almost complete absence of significant trends:thisfactshowsthatthecolorindexofstarsusedisgoodenoughfordifferentialphotometrycarriedoutinunfilteredconditions.

5. Data analysis

Before proceeding further in the analysis, the time of the light curvesobtained was heliocentrically corrected (HJD) in order to ensure a perfectcompatibilityofthedatawithobservationscarriedoutevenataconsiderabledistanceintime.Fromhereon,theobtaineddatasetwillbereferredtoasFRICinthiswork,(FRICbeingtheauthor’sAAVSOobservercode). Thedeterminationoftheperiodwascalculatedusingthesoftwareperiod04(Lenz and Breger 2005), using a Discrete Fourier Transform (DFT). Theaveragezero-point(averagemagnitudeoftheobject)wassubtractedfromthedatasettopreventtheappearanceofartifactscenteredatafrequency0.0oftheperiodogram.Allthedatapointswereweightedinrelationtotheamountofthemagnitudeerror.Theperiodogramwascalculatedwithafrequencyrangefrom0to25cd–1(cyclesperday)andstep0.00118537583cd–1.TheresultisshowninFigure5. The calculated frequency is 5.636659(89) cd–1 (SNR 12.9) with anamplitudeof0.164±0.001CV.Theperiod thusappears tobe0.1774100(28)day with a time of minimum 2456008.35376(17) HJD. The calculation oftheuncertaintieswascarriedoutwithperiod04usingthemethoddescribedinBregeret al.(1999).TheresultingphasediagramisshowninFigure6. In theVSXcatalogue (Watsonet al. 2012)maintainedby theAmericanAssociationofVariableStarsObservers(AAVSO),thestarislistedasapossibleeclipsingvariableWUMa-typeorasapulsatingvariabledSct.Byobservingthisphasediagramonecanseethatthecurveshapemuchmoreresemblestherotationofaneclipsingvariableratherthanapulsatingone.Ingeneral,itisnoteasytodistinguishbetweenEWeclipsingbinariesandpulsatingstarssuchasdSctorRRCsincemanyofthemhavesymmetriclightcurves,andsometimescomparable periods. In any case it is possible to distinguish them using thefollowingcriteria:

• TheminimaoftheEWvariablesaregenerallysharperthanmaxima.

• TheminimaoftheEWvariablesmayhaveslightdifferencesindepth.

• The EW variables can have maxima with slight differences inintensity before and after the primary minimum (O’Connell Effect)(LiuandYang2003).


• TheRRCvariablesmayhavelightcurvesslightlyasymmetricalwiththegrowthphaseslightlysteeperthanthedescendingphase.

Based on these considerations and the more plausible classification of thisvariableasaWUMasystem,IproposeanewperiodforNSVS7606408equalto P=0.3548200(28) day and HJDmin=2456015.45016(17). The new phasediagramisshowninFigure7.Thelowdispersionphasediagramallowsustorecognizethefollowingparameters:

• Theminimacenteredatphase0and0.5aresharperthanmaximapresentatphases0.25and0.75.

• Primaryminimumplacedatphase0isdeeperthantheminimumplacedat phase 0.5. The difference in intensity is estimated on the order of0.028±0.005magnitude(theresultisobtainedbycalculatingthedifferencebetweentheaveragevalueofthedataplacesbetweenphase0.95andphase0.05andthoselocatedbetweenphase0.45andphase0.55).

• The maximum placed at phase 0.25 is slightly less bright than themaximumplacedatphase0.75.Thedifferenceinintensityisestimatedon the order of 0.013±0.005 magnitude (the result is obtained bycalculatingthedifferencebetweentheaveragevalueofthedataplacesbetweenphase0.2andphase0.3and those locatedbetweenphase0.7andthephase0.8).

TheobservationssuggestthatthissystemshouldbeclassifiedasaeclipsingvariableWUMa(EW-typestar)withaperceptibledifferencebetweenprimaryandsecondaryminimumandtheexistenceofaprobableO’Connelleffect.

6. Other photometric data for NSVS 7606408

Asaseriesofphotometricmeasurementsareaccurateandprovidedwithlowscatter, thetemporalextensionof themisakeyrequirementtoallowanaccuratedeterminationof theperiod.The longer their extension, in fact, themorenoticeablewillbetheeffectthataminimumerrorinthedeterminationoftheperiodwilllendtothephasediagramobtained.Eventhephenomenonofaliasingtendtodecreaseifinthepresenceoftemporalcoveragesufficientlylongandprovidedwithadequateresolution.Myobservationsgiveaphaseplotwithreduceddispersion;untilnow,nophasediagramhasbeenpublishedforNSVS 7606408, except that associated with NSVS data, which however, isplaguedbyaverynoticeablescattering. Itwasthereforedecidedtoevaluatealltheexistingphotometricobservationsforthisstarabletoprovideareasonableamountofdatatoimprovetheperiodspecifiedabove.


Thefollowingsurveysweretakenintoconsideration:

• NSVS ThestarislistedasNSVS7606408.Thereare233observationsmadefromApril5,1999,toMarch30,2000,withameanmagnitudeof13.72±0.07(theoriginaldataare275pointsbutarereducedto233aftertherejectionontheflagNGoodPoints).Thedatawereobtainedthroughthe SkyDot service operated by LosAlamos National Laboratory (SkyDatabase for Objects in Time-Domain. Data at http://skydot.lanl.gov/nsvs/star.php?num=7606408&mask=32004). I have made a heliocentriccorrectionofthedata.

• SuperWASP The star is listed as 1SWASP J114856.59+260230.1.Thereare5,916observationsmade fromMay2,2004, toMay17,2008withameanmagnitudeof13.73±0.04(Tamflux2).Thedata,providedbythePublicSWASPArchiveintheformofDataFits,wereextractedusingfvsoftware,onlyforthevaluesTmid,Tamflux2,andTamflux2_Err.(Tmid=HJDMeanTimeofExposurefromJDReferencewhich is2453005.5;Tamflux2=Originalflux(Tamuz)correctedonthebasisofadecorrelationtechnique highlighted by Collier Cameron et al. (2006). This flux isprovidedinmicrovegasanditsconversiontomagnitudesisgivenbytheformulamag.=15–2.5log(Flux);Tamflux2_err=errorcalculatedonfluxTamflux2.) The SuperWASP data are already heliocentrically correctedandevenfor theaverage timeofexposure.ThewideavailabilityofdatarelatedtothisdatasetledmetomakeaselectiononthosethatshowedtheTamflux2_Errlessthan0.05magnitude.Thenumberofobservationsusedisthusdownto3,158withatimespanfomMay4,2004,toMay16,2007,andameanmagnitudeof13.706.

• ASAS ThestarislistedasASAS114858+2602.5.OnlydatarelatingtoASAS-3(V-Magnitude)arepresent,nottoASAS-2(I-Magnitude).Thereare139observationsmadefromJanuary2,2003,toMarch2,2009,withameanmagnitudeof13.67±0.03.(Theoriginaldataare279pointsbutarereducedto139afterdiscardingallthosewithflagD(worstdata,probablyuseless)andall thosehavingat leastonemeasure invalid(Mag0;Mag1;Mag2;Mag3;Mag4=29.999.Theaveragemagnitudewascalculatedbyperforming for eachgivendata theaverageof thevalues Mag1,Mag2;Mag3;Mag4correspondingtodifferentaperturesusedforthecalculationofthestellarflux.)ThedatawereprovidedbytheAstronomicalObservatory,UniversityofWarsaw,andarealreadyheliocentricallycorrected.

Table4showstheperioddeterminationsforeachdatasetusingthesoftwareperiod04.(Whenthesamecriteriausedfordeterminingtheperiodanduncertaintiesof FRIC dataset data were also used here, they have been omitted.) TherespectivephasediagramsandFourierspectraareshowninFigures8through13.


7. Combining the available data

DuetothedifferentspectralsensitivityoftheCCDsusedinthesesurveys(aswellasthelackortheuseofdifferentfilters),thecombinationofthedatasetscan not be trusted as regards the determination of the amplitude variation.Using theDFT,only theSWASPdataset showsanamplitudeofvariationatallsimilartotheFRICdataset(0.164±0.001)whilealltheotherdatasetsshowslightlydifferentvalues.Moreover,theNSVSandASASdatasetshaveastrongscatteringwhichcouldmakeinaccuratethecombinedFourieranalysis.SinceitisunclearhowthesedifferencesaffecttheDFTofthecombineddata,onlytheFRICandSWASPdatasetswillbeusedincombinationforthiscalculation.Inthiscase,theDFTmaybeusedonlytoobtainapossibleperiodtobeusedasagoodstartingpointforamoredetailedO–Canalysis. InordertocombinethedatasetsitwasfirstnecessarytonormalizethemeanmagnitudeoftheSWASP,NSVS,andASASdatasetstotheaveragevalueoftheFRICdataset.(FortheNSVSandASASdatasetstheoffsethasbeenappliedonlyfortherealizationofthecombinedphasediagramshowninFigure15.)TheappliedoffsetsaregiveninTable5. Theperiodogramobtained,calculatedonthefrequencybetween0and15(cd–1)withstepsof0.00001712275(cd–1)isshowninFigure14. Thechoiceofcombiningthetwodatasetshasledtoasignificantreductioninerrorsrelatingtotheperiod,theamplitudevariationandthedeterminationofthetimeofprimaryminimum. The calculated period is 5.63656978(8) cd–1 (SNR=13.068), whichcorrespondsto2P=0.35482573(3)day,theamplitudeis0.1645±0.0007mag.with HJDmin=2456015.44998(11). The resulting phase diagram for all thedatasetsbasedonthesenewparametersisgiveninFigure15. Visuallywecanseethat theNSVSdataset,whichis theearliest in time,isclearlynotinphasewiththeFRICandSWASP.Tryingtoslightlyvarytheperiod to improve the phase of NSVS we immediately lose the coincidenceof other datasets. Now it would be necessary to use an O–C analysis evenif theNSVS,ASAS,andSWASPdatasetsdidnothavea sampling rate thatallows to verify precisely the times of minimum. Due to the fact that therearenoobservations in the literature regarding the timeofminimum for thisvariablestarwewillproceedasfollows:foreachdatasetwillbetakenastimesofminimumthetimesinwhichthelightintensityislessthanmagnitude13.75.(ThelownumbersofASASdataandtheirhighdispersionrendersthemuselessforthistypeofanalysis.ThisdatasetwasnotusedforthecreationoftheO–Cdiagram.)Obviously,becauseofscattering,eventhiscalculationwillbenoisy,but if a period change is present, theO–Cdiagram should show the typicalshape(Figure16). Comparedtotheprimaryminimumobservedon2456015.44998(11)HJD,the earlier NSVS primary minimum that best represents the time shift with


respecttothecalculatedephemerisisoutofphaseby0.042(1)day.Hereitisimportant to remember that thevertical shapeof thedifferentminima in thegraphisduesolelytotheuncertaintyofthederivedtimeoftimimumrelatedtothedataset’sscattering.Ihaveusedforfittingasecondorderpolynomialandthegoodresultobtainedsuggeststhatwearefacedwithaprogressiveslowingoftheperiod.Now,ifweassumethattheperiodisslowingdownforaprobablemasstransferbetweenthetwostars,isnecessarytocalculatehowmucheachcyclemustslowdowntoaccumulatein13,326cyclesatimeshiftof0.042(1)day. (These are the complete cycles that the star has made since the earlierNSVSprimaryminimumuntilHJDmin=2456015.44998±0.00011HJD.) It isnecessary that theperiod increases4.8×10–10±1×10–11daysateachcycletobeabletoaccumulateatimeshiftof0.042(1)dayin13,326cycles.Asthecalculationisbasedonverysmallquantitiesitisnecessarytoprovideadoublecheck: it ispossible toevaluate the reliabilityof thispredictionbylooking at the data provided by period04 concerning the calculation of theperiodofeachdataset. If the period really increases by this small amount in each cycle it isnecessary that in the 13,326 cycles which separate the two minima it isincreasedby6.396×10–6days.Theperiodcalculatedbyperiod04fortheearlierNSVSdatasetis0.3548184(14)dayandifweaddtothisthevalue6.396×10–6daysweobtain0.3548248(14),whichisveryclosetotheperiodobtainedbyperiod04fortheFRICandSWASPdatacombinedasshowninTable5. Inotherwords,thedifferentlengthoftheperiodfoundbytheDFTinthemeasurementscarriedoutin1999and2000byNSVSincomparisonwiththosecarriedoutmorerecentlyisverysimilartothevariationoftheperiodcalculatedwiththeO–Cdiagram.

8. Conclusions

By combining the available data I have tried to classify the star NSVS7606408,originallyconsideredintheliteratureapossibleWUMa-ordSct-typevariablestarwithaperiodof0.17740547day.Analyzingtheobtaineddataitisbelievedpossibletoidentifythetypeofvariabilityandaprecisecalculationoftheephemeris.Thefinalresultingdataareasfollows:

Starname NSVS7606408Equatorialcoordinates (UCAC3) R.A.(2000)11h48m56.586s

Dec.(2000)+26°02'30.07"Variabilitytype EclipsingbinaryWUMaActualPeriod 0.354825732±3×10–8dayAmplitudevariation(primarymin–primarymax)


13.743±0.005CV–13.403±0.005CV=(0.340±0.005CV)Differencebetweenprimaryandsecondaryminimum 13.743±0.005CV–13.715±0.005CV=(0.028±0.005CV)Differencebetweenprimaryandsecondarymaximum 13.403±0.005CV–13.416±0.005CV=(0.013±0.005CV)Effectspresent O’ConnellEffectEphemeris HJDmin=(2456015.44998±1.1×10–4) +E×(0.35482573±3×10–8) +E2×(2.4×10–10±1×10–11)

9. Aknowledgements

IwishtothankMrs.AntonellaFinottiforhersupportinrevisingthetext,andStefanoBrangani,Ph.D.,forhisvaluablecommentsonthemathematicalaspectsofthiswork.

References

Breger,M.,et al.1999,Astron. Astrophys.,349,225.CollierCameron,A.,et al.2006,Mon. Not. Roy. Astron. Soc.,373,799.CopenhagenUniv.Obs.,et al.2006,Carlsberg Meridian Catalog 14(CMC14),

VizieROn-lineDataCatalog:I/304.Dymock,R.,andMiles,R.2009,J. British Astron. Assoc.,119,149.Lenz,P.,andBreger,M.2005,Commun. Asteroseismology,146,53.Liu,Q.-Y.,andYang,Y.-L.2003.,Chin. J. Astron. Astrophys.,3,142.Shaw,J.S.,et al.2009,“FindingperiodicvariablesintheNSVS”(https://www.

physast.uga.edu/~jss/nsvs/).Skrutskie,M.F.,et al.2006,Astron. J.,131,1163.Stead,J.J.,andHoare,M.G.2002,“NewEmpiricalIntrinsicColoursforthe

2MASSandUKIDSSPhotometricSystems” (http://www.ast.leeds.ac.uk/~phy2j2s/Intrinsic_Stead10.pdf).

Watson,C.,Henden,A.A.,andPrice,A.2012,AAVSOInternationalVariableStarIndexVSX(Watson+,2006-2011),VizieROn-lineDataCatalog:B/vsx.

Wozniak,P.R.,et al.2004,Astron. J.,127,2436.


Table 1. Activity log for the data collection concerning the FRIC dataset.TheNExTvalueindicatestheNetExposureTimewhichisthesessiondurationspentinpurephotonscollection. Date UTC Start UTC End NExT1 Useful Airmass Airmass (dd-mm-yyyy) (hh:mm:ss) (hh-mm-ss) (hh-mm-ss) Exposures Min Max

21-03-2012 18:41:11 22:34:41 02:55:07 202 1.065 1.767 22-03-2012 18:35:15 21:07:47 01:54:24 135 1.153 1.783 25-03-2012 20:57:53 22:44:12 01:19:44 94 1.058 1.149 26-03-2012 19:11:22 00:49:432 04:13:38 294 1.058 1.459 28-03-2012 20:08:08 00:45:153 03:27:50 240 1.058 1.230 22-04-2012 19:24:59 21:29:28 01:39:55 109 1.058 1.122 27-04-2012 20:38:54 23:29:46 02:17:30 150 1.058 1.282 02-05-2012 19:38:20 23:04:29 02:42:15 177 1.058 1.2661 Net Exposure Time: session duration spent in photon collection. 2 00:49:43 of 27-03-2012. 3 00:45:15 of 29-03-2012.

Table2.2MASSColorsandSpectralTyperelationasdescribedinSteadandHoare(2002). Spectral No. stars H–K J–H H–K J–H e(H–K) e(J–H) Type per (UKIDSS) (UKIDSS) (2MASS) (2MASS) subtype


MainsequenceintrinsiccolorsO8VtoM0V O8V 6 –0.10 –0.19 –0.10 –0.21 0.017 0.019 O9V 23 –0.10 –0.15 –0.09 –0.17 0.009 0.011 B0V 24 –0.10 –0.17 –0.09 –0.19 0.008 0.010 B1V 54 –0.09 –0.16 –0.08 –0.17 0.006 0.008 B2V 105 –0.06 –0.14 –0.06 –0.15 0.004 0.005 B3V 101 –0.05 –0.12 –0.05 –0.13 0.004 0.005 B4V 35 –0.04 –0.10 –0.04 –0.11 0.007 0.008 B5V 125 –0.03 –0.10 –0.03 –0.11 0.004 0.004 B6V 70 –0.02 –0.09 –0.02 –0.10 0.006 0.006 B7V 85 –0.02 –0.08 –0.02 –0.09 0.005 0.006 B8V 240 –0.02 –0.08 –0.01 –0.09 0.003 0.003 B9V 351 0.00 –0.06 0.00 –0.06 0.002 0.003 A0V 195 0.00 –0.04 0.00 –0.04 0.003 0.004 A2V 353 0.02 –0.02 0.02 –0.02 0.002 0.003 A5V 215 0.03 0.02 0.03 0.03 0.003 0.004 F0V 232 0.04 0.09 0.04 0.10 0.003 0.004 F2V 245 0.03 0.13 0.04 0.14 0.003 0.004 F5V 231 0.05 0.16 0.05 0.18 0.003 0.004


Table 3. Comparison star positions and information with respect to NSVS7606408. Object R. A. (2000) Dec. (2000) 2MASS CMC14 CMC14 Probable UCAC3 UCAC3 J–H r'mag derived spectraltype h m s ° ' " Vmag.

NSVS7606408 114856.586 +260230.07 0.226 13.532 13.641 F8V-G0VComp.Star1 114909.986 +255532.92 0.229 13.192 13.325 F8V-G0VCheckStar2 114937.454 +261448.23 0.208 13.145 13.275 F5V-F8V1 Cross references for comparison star: GSC2.2 N201201182; CMC14 114909.9+255532; USNO-B1.0 1159-0186938; NOMAD1 1159-0191730; PPMX 114909.9+255532; UCAC3 232-105102; 2MASS J11490997+2555328; SDSS J114909.99+255532.82 Cross references for check star: GSC2.2 N20120112; CMC14 114937.4+261448; USNO-B1.0 1162-0194828; NOMAD1 1162-0199537; PPMX 114937.4+261448; UCAC3 233-104578; 2MASS J11493745+2614483; SDSS J114937.45+261448.2

Table2.2MASSColorsandSpectralTyperelationasdescribedinSteadandHoare(2002),cont. Spectral No. stars H–K J–H H–K J–H e(H–K) e(J–H) Type per (UKIDSS) (UKIDSS) (2MASS) (2MASS) subtype

F8V 146 0.05 0.19 0.06 0.21 0.004 0.005 G0V 115 0.06 0.22 0.07 0.25 0.005 0.006 G2V 95 0.06 0.24 0.07 0.27 0.005 0.006 G5V 141 0.06 0.28 0.07 0.31 0.005 0.006 G8V 171 0.06 0.35 0.07 0.38 0.004 0.005 K0V 136 0.07 0.37 0.08 0.40 0.005 0.006 K2V 47 0.08 0.40 0.09 0.44 0.008 0.010 K5V 20 0.12 0.50 0.13 0.55 0.014 0.019 M0V 12 0.19 0.60 0.21 0.67 0.015 0.019

Giantintrinsiccolors:G4IIItoM5III. G5III 156 0.1270.436 0.188 0.465 0.008 0.008 G8III 585 0.1280.458 0.119 0.487 0.004 0.005 K0III 514 0.1320.493 0.123 0.522 0.004 0.005 K2III 578 0.1740.581 0.166 0.613 0.006 0.006 K5III 426 0.2230.778 0.215 0.814 0.014 0.014 M0III 179 0.2370.808 0.230 0.845 0.023 0.022 M2III 353 0.2430.903 0.235 0.941 0.017 0.017 M5III 73 0.3270.912 0.320 0.956 0.041 0.041


Table5.Offsetsappliedtothemeanmagnitudeofeachdatasetused. Dataset Original Applied New mean mag. offset mean mag.

FRIC(Furgoni,R.) 13.572 — — SWASP 13.73 –0.158 13.572 NSVS 13.72 –0.148 13.572 ASAS 13.67 –0.098 13.572

Table4.Perioddeterminationresultsforeachdataset,usingperiod04software. Dataset Checked Step SNR Period Amplitude Range (days)

NSVS 0–25(cd–1) 0.00013895(cd–1) 7.4 0.3548184(14) 0.170±0.005 SWASP 0–25(cd–1) 0.0000452(cd–1) 11.9 0.35482227(13)0.164±0.001 ASAS 5–6(cd–1) 0.0000222(cd–1)* 4.0 0.3548227(14) 0.157±0.027* Several problems afflicting this dataset: high scattering, a few observations available. Despite this, forcing the search for a frequency only between 5 (cd–1) and 6 (cd–1) we obtain a result consistent with other datasets.

Figure 1. Quantum Efficiency of the Kodak KAF8300 monochrome sensor withmicrolens, equipping the CCD SBIG ST8300m used for the data collection of thisstudy.

Wavelength (nm)

Abs

olut

e Q

E


Figure2.DSSimagecenteredonNSVS7606408.Inthetop-leftsideofthefieldthegalaxyNGC3902isclearlyvisible.Northisup,Easttotheleft.

Figure3.StarfieldcontainingNSVS7606408,thecomparisonstarUCAC3232-105102andthecheckstarUCAC3233-104578.Northisup,Easttotheleft.

Figure 4. Differential photometry of NSVS 7606408 and the check star UCAC3233-104578 in relation to the comparison star UCAC3 232-105102.The 26/03/2012sessionisshown,whichisthelongestone.Thecheckstarshowsanalmostcompleteabsence of significant trends: this fact shows that the color index of stars usedis good enough for differential photometry carried out in unfiltered conditions.


Figure5.FourierspectrumoftheFRICdatasetweightedinrelationtothemagnitudeerror.Theperiodogramwascalculatedwithafrequencyrangefrom0to25cd–1(cyclesperday)andstep0.00118537583cd–1.

Figure6.PhaseplotoftheFRICdatasetwithperiod0.1774100day.

Figure7.PhaseplotoftheFRICdatasetwithperiod0.3548200day.TheshapeofaWUmatypevariablestarisevident.

0.0 4.0 8.0 12.0 16.0 20.0 24.0Frequency

0.14

0.10

0.06

0.02

0.00

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plitu

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Figure8.PhaseplotoftheNSVSdatasetwithperiod0.3548184day.

Figure9.FourierspectrumoftheNSVSdatasetweightedinrelationtothemagnitudeerror.Theperiodogramwascalculatedwithafrequencyrangefrom0to25cd–1(cyclesperday)andstep0.00013895(cd–1).

Figure10.PhaseplotoftheSWASPdatasetwithperiod0.35482227day.

0.0 4.0 8.0 12.0 16.0 20.0 24.0Frequency

0.16

0.12

0.08

0.04

0.00

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Figure11.FourierspectrumoftheSWASPdatasetweightedinrelationtothemagnitudeerror.Theperiodogramwascalculatedwithafrequencyrangefrom0to25cd–1(cyclesperday)andstep0.0000452(cd–1).

Figure12.PhaseplotoftheASASdatasetwithperiod0.3548227day.

Figure13.FourierspectrumoftheASASdatasetweightedinrelationtothemagnitudeerror.Theperiodogramwascalculatedwithafrequencyrangefrom0to25cd–1(cyclesperday)andstep0.0000222(cd–1).Thearrowmarksthesignificantpeak.

0.0 4.0 8.0 12.0 16.0 20.0 24.0Frequency

0.12

0.08

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0.00

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5.0 5.2 5.4 5.6 5.8 6.0Frequency

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Figure14.FourierspectrumoftheFRIC+SWASPdatasets.Anoffsetof–0.158maghas been applied to SWASP to normalize the mean magnitude to that of FRIC.Theperiodogramwascalculatedwithafrequencyrangefrom5to6cd–1(cyclesperday)andstep0.00001712275(cd–1).

Figure 15. Phase plot of FRIC, SWASP, NSVS, and ASAS dataset with period of0.35482573 day.We can see that the NSVS dataset, which is the earliest in time, isclearlynotinphasewiththeFRICandSWASP.

Figure16.O–CanalysisforthetimeofprimaryminimumofNSVS7606408.

0.0 4.0 8.0 12.0Frequency

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Bohme, JAAVSO Volume 40, 2012 973

Is MP Geminorum an Eclipsing Binary With a Very Long Period?

Dietmar BöhmeDorfstrasse 11, D-06682 Nessa, Germany; [email protected]

Received September 7, 2011; revised January 26, 2012; accepted January 27, 2012

Abstract PerhapsMPGemisaverylong-periodeclipsingbinarystar.Onlynineobservationsofaminimumexisttothisday.TheauthorobservedthestaronplatesoftheSonnebergObservatoryanddidnotfindanyfurtherminima.ContinuedmonitoringbyCCDobserversisrecommended.1. Introduction

Hoffmeister(1963)discoveredthevariablestarMPGeminthefieldnGemof the “Sonneberger Felderplan” (Figure 1). He wrote: “the star is invisible1944February24/25(2plates),February25/26(7plates),onallotherplatesbright,perhapswithvery lowchanges.Onneighboringdaysnoplatesexist.Perhaps anAlgol-like star with a long period.” I have checked these platesagainandcanconfirmthatthestarwasinvisibleonthosedates. Gessner(1973,whereMPGemislistedasS7958Gemonp.589)observedMPGemonallplatesavailableatSonnebergin1973.Shecouldnotfindanyfurtherminimaandnoted:“thevariableconsistsofcomponents,thesoutherncomponent is blue (Palomar atlas, page 417).” The variable is the southcomponent. Nofurtherobservationsofthestarareknown.Ithereforehaveobservedthestaronall119laterplatesoftheSonnebergskypatrolfromtheyears1981to1994.Icouldnotfindanyfurtherminima.AlightcurveforMPGemisshowninFigure2, basedonmagnitudes estimated from theSonnebergplates.ThecomparisonstarwasUSNO1050-04327215(mpg15.6).

2. Discussion and conclusion

BrightnessmeasurementsinBVRIJHKofthestarexistindifferentcatalogs.ThesemeasurementsshowthatitprobablyisastarofspectraltypeA. Thestar isabout16thmagnitude inVandsocouldbemonitoredeasilywith amateur telescopes. The VSP chart is very good for finding, but mostplanetariumprograms(Guide8.0)showthestaratafaultyposition.ThecorrectpositionisR.A.06h48m33.3s, Dec. +19º 37´ 15˝ (J2000). I would like to call for theobservationofthestar,sothatitispossibletoconfirmtheperiod,whichispresumablyverylong.

Bohme, JAAVSO Volume 40, 2012974

References

Hoffmeister,C.1963,Astron. Nachr.,287,169.Gessner,H.1973,Veröff. Sternw. Sonneberg.,7,589.

Figure1.FieldofviewofMPGem(SonnebergSkyPatrol).Star“a”isUSNO1050-04324543.

Figure2.LightcurveofMPGem(uperdata)frommagnitudesestimatedfromtheSonnebergplates.ThecomparisonstarwasUSNO1050-04327215(mpg15.6,lowerdata).Trianglesindicatestarnotvisible/fainter-than.


Recent Minima of 150 Eclipsing Binary Stars

Gerard SamolykP.O. Box 20677; Greenfield, WI 53220; [email protected]

Received January 23, 2012; accepted January 23, 2012

Abstract Thispapercontinuesthepublicationoftimesofminimaforeclipsingbinarystars fromobservations reported to theAAVSOEBsection.Timesofminima from observations made from April 2011 through December 2011alongwithsomeunpublishedtimesofminimafromolderdataarepresented.

1. Recent Observations

The accompanying list contains times of minima calculated from recentPEP and CCD observations made by participants in theAAVSO’s eclipsingbinaryprogram.Thislistwillbeweb-archivedandmadeavailablethroughtheAAVSOftpsiteat ftp://ftp.aavso.org/public/datasets/gsam2j402.txt.This list,alongwiththeeclipsingbinarydatafromearlierAAVSOpublications,isalsoincludedintheLichtenkneckerdatabaseadministratedbytheBundesdeutscheArbeitsgemeinschaftfürVeränderlicheSternee.V.(BAV)at:http://www.bav-astro.de/LkDB/index.php?lang=en. These observations were reduced by theobserversorthewriterusingthemethodofKweeandVanWorden(1956).Thestandarderrorisincludedwhenavailable.ColumnFinTable1indicatesthefilterused.A“C”indicatesaclearfilter. ThelinearelementsintheGeneral Catalogue of Variable Stars(GCVS;Kholopovet al.1985)wereusedtocomputetheO–Cvaluesformoststars.ForafewexceptionswheretheGCVSelementsaremissingorareinsignificanterror, light elements fromanother sourceareused:CDCam (BaldwinandSamolyk 2007), CW Cas (Samolyk 1992a), V1115 Cas (Kholopov et al.2011), Z Dra (Danielkiewicz-Krośniak and Kurpińska-Winiarska 1996), DF Hya (Samolyk 1992b), EF Ori (Baldwin and Samolyk 2005), GU Ori(Samolyk1985).LightelementsforV471Cas,BCEri,V728Her,CDLyn,V1128Tau, KM UMa, and MSVir are from up-to-date linear elements ofeclipsing binaries (Kreiner 2012). O–C values listed in this paper can bedirectly compared with values published in the AAVSO Observed Minima Timings of Eclipsing Binariesseries.


References

Baldwin,M.E.,andSamolyk,G.2005,Observed Minima Timings of Eclipsing Binaries No. 10,AAVSO,Cambridge,MA.

Baldwin,M.E.,andSamolyk,G.2007,Observed Minima Timings of Eclipsing Binaries No. 12,AAVSO,Cambridge,MA.

Danielkiewicz-Krośniak, and E. Kurpińska-Winiarska, M., eds. 1996, Rocznik Astron. (SAC68),68,1.

Kholopov,P.N.,et al.1985,General Catalogue of Variable Stars,4thed.,Moscow.Kholopov, P. N., et al. 2011, General Catalogue of Variable Stars, Online

Edition(http://www.sai.msu.su/gcvs/gcvs/index.htm).Kreiner, J.M.2012,Up-to-date linear elementsof eclipsingbinaries (http://

www.as.up.krakow.pl/ephem/).Kwee,K.K.,andVanWorden,H.1956,Bull. Astron. Inst. Netherlands,12,327.Samolyk,G.1985, J. Amer. Assoc. Var. Star Obs.,14,12.Samolyk,G.1992a, J. Amer. Assoc. Var. Star Obs.,21,34.Samolyk,G.1992b, J. Amer. Assoc. Var. Star Obs.,21,111.

JD(min) STANDARDSTAR HEL. CYCLEO-C F OBSERVER ERROR 2400000+

Star JD (min) Cycle O–C F Observer Standard HJD 2400000+ (day) Error (day)

Table1.RecenttimesofminimaofstarsintheAAVSOeclipsingbinaryprogram.

RTAnd 55516.6920 22856 –0.0100 V R.Poklar 0.0001

RTAnd 55850.6541 23387 –0.0094 V K.Menzies 0.0001 WZAnd 55836.6375 21511 0.0569 V G.Samolyk 0.0002 XZAnd 55836.7518 23473 0.1738 V G.Samolyk 0.0001 ABAnd 55748.7710 59173.5 –0.0284 V K.Menzies 0.0002 ABAnd 55793.5776 59308.5 –0.0273 R L.Corp 0.0004 ABAnd 55838.3811 59443.5 –0.0292 R L.Corp 0.0001 ABAnd 55838.5476 59444 –0.0286 R L.Corp 0.0002 ABAnd 55890.3218 59600 –0.0296 R L.Corp 0.0001 ABAnd 55906.5850 59649 –0.0291 V G.Samolyk 0.0002 BDAnd 55824.9533 45069 0.0095 V R.Sabo 0.0003 BXAnd 55873.6462 31707 –0.0586 V K.Menzies 0.0001 BXAnd 55906.5895 31761 –0.0615 V G.Samolyk 0.0002 DSAnd 55864.7039 19517 0.0036 V N.Simmons 0.0002 CXAqr 55907.5249 34990 0.0128 V G.Samolyk 0.0001 OOAql 55773.6378 33861 0.0509 V K.Menzies 0.0003 OOAql 55773.6378 33861 0.0509 V N.Simmons 0.0002 OOAql 55790.3637 33894 0.0528 R L.Corp 0.0001 OOAql 55793.4035 33900 0.0518 R L.Corp 0.0002 OOAql 55825.3320 33963 0.0527 R L.Corp 0.0006




Table1.RecenttimesofminimaofstarsintheAAVSOeclipsingbinaryprogram,cont.

SSAri 55866.6860 41475 –0.2936 V R.Poklar 0.0002 SXAur 55923.6455 13025 0.0154 V R.Poklar 0.0002 TTAur 55890.6875 25998 –0.0134 V G.Samolyk 0.0001 TTAur 55902.6839 26007 –0.0116 V R.Poklar 0.0003 TTAur 55914.6787 26016 –0.0115 V N.Simmons 0.0001 APAur 55874.7679 23589.5 1.3617 V K.Menzies 0.0001 APAur 55890.7106 23617.5 1.3636 V G.Samolyk 0.0003 CLAur 55838.8305 18380 0.1490 V G.Samolyk 0.0002 CLAur 55924.6936 18449 0.1509 V R.Poklar 0.0002 EPAur 55872.8002 50022 0.0160 V K.Menzies 0.0001 HPAur 55797.9141 9166 0.0608 V R.Sabo 0.0002 HPAur 55889.6847 9230.5 0.0600 V G.Samolyk 0.0003 IMAur 55844.7034 12290 –0.1109 V G.Samolyk 0.0002 TUBoo 55654.6273 69655.5 –0.1359 V K.Menzies 0.0002 TUBoo 55718.6727 69853 –0.1371 V N.Simmons 0.0001 TYBoo 55718.2987 66965 0.0780 C Y.Ogmen 0.0001 TZBoo 55666.7288 53956.5 0.0655 V K.Menzies 0.0004 TZBoo 55699.7121 54067.5 0.0639 V G.Samolyk 0.0004 TZBoo 55704.3151 54083 0.0609 C Y.Ogmen 0.0001 TZBoo 55716.6510 54124.5 0.0645 V K.Menzies 0.0003 VWBoo 55745.6648 71781 –0.1936 V G.Samolyk 0.0002 YCam 55923.6781 3921 0.3973 V G.Samolyk 0.0002 SVCam 55893.6696 22424 0.0539 V R.Poklar 0.0001 CDCam 55905.7874 4113 –0.0009 V G.Samolyk 0.0004 AMCMi 55897.8921 30076 0.2010 V K.Menzies 0.0003 TYCap 55836.6486 7758 0.0731 V G.Samolyk 0.0002 TVCas 55838.7074 6199 –0.0261 V G.Samolyk 0.0003 TWCas 55844.5549 9687 –0.0070 V G.Samolyk 0.0003 TWCas 55864.5530 9701 –0.0054 V N.Simmons 0.0002 CWCas 55914.5221 44791.5 –0.0642 V G.Samolyk 0.0002 IRCas 55875.6672 19850 0.0080 V R.Poklar 0.0001 ISCas 55857.6111 14706 0.0667 V K.Menzies 0.0001 ORCas 55872.7162 9362 –0.0248 V K.Menzies 0.0001 V380Cas 55798.6136 22216 –0.0684 V N.Simmons 0.0003 V380Cas 55836.6183 22244 –0.0673 V N.Simmons 0.0002 V380Cas 55844.7634 22250 –0.0658 V K.Menzies 0.0002 V380Cas 55889.5527 22283 –0.0666 V G.Samolyk 0.0005 V471Cas 55923.6121 8538.5 0.0016 V G.Lubcke 0.0002



V471Cas 55923.6122 8538.5 0.0017 I G.Lubcke 0.0001 V1115Cas 55923.5541 7842 –0.0551 I G.Lubcke 0.0001 V1115Cas 55923.5542 7842 –0.0550 V G.Lubcke 0.0007 SUCep 55806.6959 32706 0.0065 V G.Samolyk 0.0001 WWCep 55836.7798 20088 0.3280 V G.Samolyk 0.0001 WZCep 55747.6643 66373 –0.1081 V N.Simmons 0.0001 XYCep 50702.637 2491 –0.0258 C S.Cook XYCep 51465.637 2766 –0.0207 C S.Cook DKCep 55836.5917 22564 0.0367 V G.Samolyk 0.0001 DLCep 55747.8256 13371 0.0561 V G.Samolyk 0.0003 EGCep 55689.8277 24045 0.0133 V G.Samolyk 0.0001 EKCep 55810.6345 3796 0.0098 V G.Samolyk 0.0001 GKCep 49311.725 11341 0.0622C(PEP)R.Benge 0.0004 GKCep 50675.721 12798 0.0774 C S.Cook 0.0003 GKCep 51057.682: 13206 0.0864 C S.Cook 0.0005 SSCet 55905.6333 4524 0.0369 V G.Samolyk 0.0001 SSCet 55911.5810 4526 0.0366 V R.Poklar 0.0008 TTCet 55811.9036 47877 –0.0658 V R.Sabo 0.0002 TTCet 55888.6840 48035 –0.0665 V R.Poklar 0.0001 TWCet 55891.6792 42664.5 –0.0267 V R.Poklar 0.0001 TXCet 55903.6244 17306 0.0087 V R.Poklar 0.0002 RWCom 55921.9726 66989 –0.0082 V G.Samolyk 0.0002 RWCom 55924.9399 67001.5 –0.0077 V K.Menzies 0.0001 RZCom 55666.5871 61532.5 0.0444 V K.Menzies 0.0002 CCCom 55664.6330 73095 –0.0136 V N.Simmons 0.0003 TWCrB 52428.8443 24675 0.0283 V S.Dvorak 0.0002 TWCrB 53091.9185 25801 0.0312 V S.Dvorak 0.0003 TWCrB 55748.3357 30312 0.0410 R Y.Ogmen 0.0001 ZZCyg 55810.6136 17197 –0.0603 V G.Samolyk 0.0001 AECyg 55867.5625 11640 –0.0053 V N.Simmons 0.0003 CGCyg 55759.7491 25881 0.0668 V K.Menzies 0.0002 CGCyg 55785.6255 25922 0.0664 V N.Simmons 0.0001 DKCyg 55479.7104 37137 0.0916 V G.Samolyk 0.0003 DKCyg 55810.6074 37840 0.0932 V N.Simmons 0.0002 KRCyg 55838.5786 31630 0.0173 V G.Samolyk 0.0005 V388Cyg 55790.6151 16108 –0.0934 V N.Simmons 0.0001 V401Cyg 55812.6005 20554 0.0735 V N.Simmons 0.0001 V456Cyg 55769.6862 12184 0.0474 V K.Menzies 0.0003








V466Cyg 55770.7815 19400 0.0065 V K.Menzies 0.0004 V836Cyg 55744.5868 16668 0.0220 R L.Corp 0.0005 V1073Cyg50657.644: 15251 –0.0839 C S.Cook V1073Cyg54085.5347 19613 –0.1132 V V.Petriew 0.0004 TTDel 55806.6615 3683 –0.0888 V G.Samolyk 0.0002 TYDel 55778.4084 10762 0.0558 R L.Corp 0.0011 TYDel 55792.7025 10774 0.0564 V R.Sabo 0.0003 DMDel 50309.745 6876.5 –0.0594 C S.Cook DMDel 55773.4976 13345 –0.0923 R L.Corp 0.0006 FZDel 55792.6349 31241 –0.0389 V N.Simmons 0.0001 ZDra 55921.6210 4477 –0.0196 V G.Samolyk 0.0001 TZDra 52494.5844 11002 –0.0114 V S.Dvorak 0.0003 TZDra 53309.5192 11943 –0.0152 V S.Dvorak 0.0003 AXDra 52435.5845 45177 –0.0536 V S.Dvorak 0.0001 AXDra 52975.9090 46128 –0.0534 V S.Dvorak 0.0001 BVDra 50590.685 17472 –0.0144 C S.Cook BVDra 51056.629 18803 –0.0097 C S.Cook SEqu 55777.6736 3836 0.0624 V N.Simmons 0.0001 SVEqu 50309.550 12403 0.0800 C S.Cook SVEqu 50310.004 12403.5 0.0935 C S.Cook YYEri 55836.8182 44340 0.1436 V G.Samolyk 0.0001 YYEri 55906.7428 44557.5 0.1432 V G.Samolyk 0.0001 YYEri 55926.6762 44619.5 0.1440 V R.Poklar 0.0001 BCEri 53304.8230 1526 0.0011 V S.Dvorak 0.0020 BCEri 53369.6753 1649 0.0014 V S.Dvorak 0.0004 SXGem 55854.8866 26940 –0.0498 V R.Sabo 0.0004 WWGem 55858.8461 24135 0.0206 V K.Menzies 0.0003 HRGem 52549.8571 20796 0.0146 V S.Dvorak 0.0001 HRGem 52578.7190 20823 0.0145 V S.Dvorak 0.0002 RXHer 55336.7469 12463 0.0011 V G.Samolyk 0.0004 RXHer 55795.6170 12721 –0.0005 V N.Simmons 0.0002 SZHer 55673.7814 16880 –0.0227 V K.Menzies 0.0001 SZHer 55836.5822 17079 –0.0235 V G.Samolyk 0.0001 TTHer 55745.6655 17268 0.0385 V G.Samolyk 0.0001 TUHer 55747.6338 5155 –0.2158 V G.Samolyk 0.0003 LTHer 55752.3184 13834 –0.1306 C Y.Ogmen 0.0001 LTHer 55778.3450 13858 –0.1211 C Y.Ogmen 0.0001 V728Her 51704.6717 –1688 0.0075 V J.Howell 0.0004


V728Her 52752.8244 536 0.0030 V S.Dvorak 0.0004 VZHya 55923.5621 5395 0.0040 R L.Corp 0.0003 DFHya 55654.5906 38919 –0.0106 V N.Simmons 0.0001 DFHya 55878.9067 39597.5 –0.0101 V K.Menzies 0.0001 FGHya 52347.5530 22509.5 –0.0578 V S.Dvorak 0.0010 FGHya 52629.8087 23370.5 –0.0655 V S.Dvorak 0.0006 FGHya 53025.8222 24578.5 –0.0730 V S.Dvorak 0.0006 FGHya 53088.6048 24770 –0.0702 V S.Dvorak 0.0003 SWLac 55856.4707 32992 –0.1009 R L.Corp 0.0002 VXLac 55889.5903 9894 0.0787 V G.Samolyk 0.0001 CMLac 55907.5513 17998 –0.0041 V G.Samolyk 0.0002 COLac 55751.8415 18297 –0.0019 V N.Simmons 0.0003 COLac 55775.7447 18312.5 –0.0029 V K.Menzies 0.0002 UVLeo 55664.3946 28702 0.0349 R L.Corp 0.0001 UZLeo 55661.4231 25663.5 –0.0913 R L.Corp 0.0005 XYLeo 55653.4706 37237 0.0637 R L.Corp 0.0004 AMLeo 55659.3644 35992.5 0.0125 R L.Corp 0.0004 APLeo 55653.4048 37450 –0.0293 R L.Corp 0.0003 APLeo 55659.4298 37464 –0.0293 R L.Corp 0.0004 SWLyn 52629.7070 13437 0.0371 V S.Dvorak 0.0001 SWLyn 53012.9317 14032 0.0441 V S.Dvorak 0.0001 CDLyn 51956.8230 –120 0.0026 V S.Dvorak 0.0010 CDLyn 51979.5681 –115 0.0003 V S.Dvorak 0.0003 FLLyr 55718.6648 8033 –0.0020 V G.Samolyk 0.0001 bLyr 55836.21 529 1.55 R G.Samolyk 0.01 bLyr 55836.22 529 1.56 V G.Samolyk 0.02 bLyr 55836.30 529 1.64 B G.Samolyk 0.02 bLyr 55842.51 529.5 1.38 V G.Samolyk 0.02 bLyr 55842.60 529.5 1.47 B G.Samolyk 0.02 bLyr 55842.61 529.5 1.48 R G.Samolyk 0.03 RWMon 55874.9343 11644 –0.0737 I R.Sabo 0.0001 EPMon 55914.8879 20056 0.0323 V G.Samolyk 0.0002 V451Oph 55751.4441 4970 –0.0038 R L.Corp 0.0004 V501Oph 52475.3887 22278 –0.0053 V L.Baldinelli 0.0005 V501Oph 52506.3610 22310 –0.0074 V L.Baldinelli 0.0004 EFOri 55911.7618 2199 0.0050 V G.Samolyk 0.0003 EROri 55890.8172 33690 0.1000 V G.Samolyk 0.0001 EROri 55915.7982 33749 0.1005 V R.Sabo 0.0001








FROri 52265.7152 27632 0.0191 V S.Dvorak 0.0002 FROri 52342.5496 27719 0.0184 V S.Dvorak 0.0001 FROri 54102.6977 29712 0.0243 V R.Poklar 0.0001 FROri 54139.7893 29754 0.0231 V J.Bialozynski 0.0006 FTOri 55925.6701 4627 0.0167 V R.Poklar 0.0001 GUOri 55921.7978 27305 –0.0499 V G.Samolyk 0.0003 UPeg 55844.6258 51585 –0.1430 V G.Samolyk 0.0001 ATPeg 52270.5261 6152 0.0079 V S.Dvorak 0.0002 ATPeg 52976.5136 6768 0.0123 V S.Dvorak 0.0005 BBPeg 55790.5999 33267.5 –0.0046 V K.Menzies 0.0001 BBPeg 55837.5955 33397.5 –0.0043 V G.Samolyk 0.0001 BBPeg 55845.5487 33419.5 –0.0041 V K.Menzies 0.0001 BXPeg 55838.6233 41521 –0.1058 V G.Samolyk 0.0001 BXPeg 55845.6342 41546 –0.1055 V K.Menzies 0.0001 GPPeg 55786.6940 14912 –0.0481 V K.Menzies 0.0001 RTPer 55882.6933 26497 0.0747 V R.Poklar 0.0001 RVPer 55914.6450 7027 –0.0015 V G.Samolyk 0.0001 XZPer 55837.9646 10707 –0.0593 V R.Sabo 0.0001 ITPer 53339.7475 15620 0.0054 V S.Dvorak 0.0003 ITPer 54095.8632 16113 –0.0058 V J.Bialozynski 0.0006 ITPer 54115.8064 16126 –0.0011 V J.Bialozynski 0.0006 V432Per 52503.8691 51722 –0.0092 V S.Dvorak 0.0002 V432Per 52629.5940 52113 0.0026 V S.Dvorak 0.0001 V432Per 52973.8089 53183.5 0.0335 V S.Dvorak 0.0002 bPer 55837.7575 3556 0.1100 V G.Samolyk 0.0002 YPsc 55836.6946 2709 –0.0092 V G.Samolyk 0.0001 RVPsc 55868.6393 56837 –0.0527 V R.Poklar 0.0001 CCSer 55701.6856 35308 0.9687 V G.Samolyk 0.0002 YSex 50519.621 20850 0.0276 C S.Cook YSex 51608.635 23444 0.0213 C S.Cook RWTau 55806.8207 3656 –0.2463 V G.Samolyk 0.0001 CTTau 55874.8717 15702 –0.0567 V K.Menzies 0.0001 EQTau 55826.9198 45741 –0.0260 V R.Sabo 0.0001 EQTau 55844.8411 45793.5 –0.0255 V G.Samolyk 0.0002 EQTau 55865.6639 45854.5 –0.0250 V K.Menzies 0.0001 EQTau 55921.6445 46018.5 –0.0255 V G.Samolyk 0.0001 V1128Tau 55923.3619 11210 0.0009 R L.Corp 0.0002 V1128Tau 55923.5154 11210.5 0.0017 R L.Corp 0.0006


VTri 55837.8148 53594 –0.0045 V G.Samolyk 0.0001 XTri 55806.8448 13694 –0.0792 V G.Samolyk 0.0001 XTri 55881.6520 13771 –0.0802 V R.Poklar 0.0001 XTri 55920.5129 13811 –0.0807 V N.Simmons 0.0001 RSTri 55790.7941 9351 –0.0386 V K.Menzies 0.0003 RVTri 55905.5500 13099 –0.0352 V G.Samolyk 0.0001 WUMa 55906.9130 30396 –0.0706 V G.Samolyk 0.0001 TXUMa 55921.8507 3566 0.1958 V G.Samolyk 0.0001 TYUMa 55717.6631 45650.5 0.3022 V K.Menzies 0.0002 UXUMa 55757.2760 93173 0.0024 C Y.Ogmen 0.0001 VVUMa 55914.9607 14693 –0.0501 V G.Samolyk 0.0001 XZUMa 55648.6327 7756 –0.1072 V N.Simmons 0.0001 XZUMa 55907.7609 7968 –0.1109 V G.Samolyk 0.0001 KMUMa 55692.2752 9072 –0.0017 C Y.Ogmen 0.0001 AHVir 55698.6342 24254 0.2349 V N.Simmons 0.0003 AXVir 50567.641 32735 0.0018 C S.Cook AXVir 52402.6425 35347 0.0049 V S.Dvorak 0.0001 BFVir 52406.6237 9891 0.0618 V S.Dvorak 0.0005 BFVir 53097.8067 10970 0.0698 V S.Dvorak 0.0001 MSVir 52371.7634 –410.5 0.0033 V S.Dvorak 0.0003 MSVir 52407.6931 –295.5 0.0026 V S.Dvorak 0.0003 MSVir 53150.6746 2082.5 0.0060 V S.Dvorak 0.0003 AWVul 55784.6403 11779 –0.0159 V N.Simmons 0.0001 BEVul 55718.8180 10056 0.0825 V G.Samolyk 0.0001 BEVul 55763.8270 10085 0.0823 V R.Sabo 0.0001 BEVul 55788.6603 10101 0.0829 V N.Simmons 0.0001 BSVul 55779.6050 26279 –0.0273 V K.Menzies 0.0001 BTVul 55773.7433 17851 0.0021 V K.Menzies 0.0004 BUVul 55837.6585 39199 0.0189 V G.Samolyk 0.0001 CDVul 55747.8599 13820 –0.0010 V G.Samolyk 0.0002 ERVul 54008.7294 19806 0.0158 V V.Petriew 0.0023 ERVul 54078.5378 19906 0.0147 V V.Petriew 0.0006



Richards, JAAVSO Volume 40, 2012 983

The Variable Stars South Eclipsing Binary Database

Tom RichardsDirector, Variable Stars South, Pretty Hill Observatory, P.O. Box 323, Kangaroo Ground, Vic 3097, Australia; [email protected]

Received October 1, 2012; revised October 18, 2012; accepted October 18, 2012

Abstract VariableStarsSouth(VSS)hasthreeactiveprojectsusingelectronicdetectorstostudyeclipsingbinaries,especiallyEAs.InadditiontosupplyingJDobservationaldata to theAAVSO InternationalDatabase,VSSmaintainsa database of observed times of minima (ToM) and linear light elementsderived from the ToMs. This database, located on the VSS website www.variablestarssouth.org, is updated monthly. In addition, the same page linkstotheareasforthethreeprojectswhichmaintainextensiveobservationalandanalyticdata.

1. Introduction

Variable Stars South (VSS) is an online organization of astronomersinterestedinstudyingsouthernvariablestars.ItisaresearchsectionoftheRoyalAstronomicalSocietyofNewZealand.AllinformationaboutVSSincludingitscollecteddatacanbefoundonitswebsite,www.variablestarssouth.org.VSSprimarilyactsasahosttoprojectsorganizedbyindividualsorteams,andthreesuchare:

• EquatorialEclipsingBinaries(EEB),jointwiththeBritishAstronomicalAssociationVariableStarSection;leaderTomRichards.

• SearchforPlanetsaroundDetachedEclipsingBinaries(SPADES);leadersSimonO’Toole(AustralianAstronomicalObservatory)andTomRichards.

• SouthernBinariesDSLR(SBD),leaderMarkBlackford.

Although these projects have very different goals, they all collect andanalyzeelectronic(DSLRandCCD)timeseriesdataoneclipsesofbinarystarsystems.Informationabouteachproject,includingsciencecases,observationalrequirements,andguidesforobserversandanalysts,aswellasobservationaldata and analyses, can be found under the Research Projects menu on theVSSwebsite.Collaborationintheseprojects isopentoanyastronomerwithappropriateequipment.Theeclipsedatafromthethreeprojectsarecollectedintoasingledownloadablefile, theVSSEclipsingBinaryDatabase.JDdatafromtheseobservationsarealsosuppliedbyindividualobserverstotheAAVSOInternational Database—a requirement on all VSS observational projects.Thereisnofixednortherlylimittothetargetsinanyoftheprojects—themainrequirement is to be well observable from temperate southern latitudes.AtpresentthemostnortherlytargetisLTHerinSPADES,at+09°57'52''.

Richards, JAAVSO Volume 40, 2012984

2. The VSS EB database

Typically,whenanobserverinoneoftheprojectsobtainsameasureabletimeseriesonaneclipse,ananalysisiscarriedouttodeterminetimeofminimum(ToM)andotherresultsofinterest,whicharethenstoredintheproject’sareaontheVSSwebsite.Forexample,intheSPADESobservationarea,onemayfindunderthesub-areaforeachtargetsystem:

• Excel Observation Files of every observation set obtained—all to afixedformat,assubmittedbytheobserver.

• AnExcelResultsFilemaintainedby the analyst responsible for thattargetsystem,containing:allToMsmeasuredfromtheObservationFiledata; sets of linear light elements (LEs) published by others (such asGCVS);calculationsofO–CoftheToMsagainstapublishedLEset(suchasGCVS);andwheresufficientmeasuredToMsexist,alinearestimateoftheLEsfromtheToMs.

• Aperanso(www.peranso.com)fileofalltheobservationaldataintheprojectforthetarget,andassociatedinformationandplots.

• AtextfileofalltheHJDdataforthetargetobtainedintheproject.

TheVSSEBdatabaseconsolidatesToMandLEdataobtainedandrecordedinthethreeprojectsintheirowndifferentways,sothatresearchershavea“one-stopshop”forsuchcommonlyrequireddata.Atpresent,itcontainsdataon91systems.ThefileitselfisinCSVplaintextformat.Itisupdatedmonthly(that’sanintention,notapromise!)tocontainnewdataandalsotorefineorcorrectolddataasimprovedanalysesarecarriedout.Someolddata,suchas“eyeball”estimatesofpoorly recordedminima intendedas roughguides toobservers,mayevenberemovedwhenbetterdatabecomeavailable.

Theformatofthefileisgivenbelow.Itmaychangeinfuturewhenitbecomesapparentthatachangewouldbeforthebetter;butitisalwaysaccompaniedbyaReadmefilespecifyingthecurrentformat.

System—Nameofthebinarysystem.Formatisconstellationabbreviation,thenGCVSidentificationwhereavailable,with3-digitV...identificationsexpandedwithaleading"0"(forexample,AraV0536).WheretheGCVSidentification is not available the constellation abbreviation is retainedthen another catalogue identifier is used, whose provenance should beobvious.The table is sorted lexically on this column, so, for example,"Sco"entriesprecede"Sgr",and"GruRU"precedes"GruW".

NextcomefivecolumnsrecordingToMmeasurements:

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Type—p=primarymin,s=secondarymin.

HJD_min—MeasuredHJDofminimum,tothesamenumberofsignificantdecimalplacesastheerror(nextcolumn).TherowsforagivensystemaresortedonHJD_min,earliestfirst.

Error—Measured uncertainty in HJD_min, to one or two significantfigures.

Min V mag—MeasuredmagnitudeofminimuminJohnsonVband.

Min B mag—MeasuredmagnitudeofminimuminJohnsonBband.

Min R Mag—MeasuredmagnitudeofminimuminCousinsRband.

Notes—Anyusefulinformationontheprecedingdata.

Next come four columns recording measured linear light elements. In rowswhere these occur, they are derived from linear regressions on the minimameasurements recorded in that row and the preceding rows for that system.Thusitispossibletocountthenumberofdatapointsintheregression;andforagivensystemlaterrowswillhaveregressionsbasedonmoredatapoints.

E0—The HJD zero epoch for the elements, to the same number ofsignificantdecimalplacesastheerror(nextcolumn).Thiswillbeclosetooneofthemeasuredminimainthisorprecedingrows.

E0 error—The measured uncertainty in E0, to one or two significantfigures.

P—Themeasuredorbitalperiodofthesystemindays,tothesamenumberofsignificantdecimalplacesastheerror(nextcolumn).

P error—The measured uncertainty in P, to one or two significantfigures.

Otherdatafollow:

Spectrum—Spectraltypeand/orclass,derivedfromaspectrumtakenfortheproject.Thisisenteredintothelastrowforthesystemthatexistsatthetimethespectralanalysiswascarriedout.

Project—Abbreviationoftheprojectname.

3. Conclusion

The VSS EB database is a downloadable file in CSV text-only formatcontainingdataonsoutherneclipsingbinariesobtainedinthreeVSSprojects.Thedata,updatedmonthly,consistofmeasuredtimesofminima,lightelements,andspectra.Atpresentitcontainsdataon91systems.

Holmberg, JAAVSO Volume 40, 2012986

A Note on the Variability of V538 Cassiopeiae

Gustav HolmbergKarl XI-gatan 8A, SE-222 20 Lund, Sweden; [email protected]

Received December 28, 2011; revised February 9, 2012; accepted February 13, 2012

Abstract CCD observations of V538 Cas have been made on nine nightsduring three weeks using the AAVSO Bright Star Monitor. No significantvariationswerefound.

1. Discovery

Weber (1958a) discovered variations in the star BD +60˚ 201 (HD 7681, HIP6084,R.A.01h18m07.2s Dec. +61˚ 43' 04" (J2000)) by analyzing plates takenbetween1942 and1958.The starwas found tovarybetween9.0 and9.6 photographic magnitude and Weber, who did not publish a light curve,suspecteditcouldbeaneclipsingvariableoftheAlgoltype.AfurtherstudyofthestarwasmadebyHäussler(1974)whoused135patrolcameraplatestofindthestarvaryingirregularlybetween9.44and10.01photographicmagnitude.Heclassifieditasanirregularvariablestar,typeIsb. Onthebasisofthesestudies,thestarwasdesignatedV538Cas.Theentryin the General Catalogue of Variable Stars (GCVS; Samus et al. 2011) ofthestarhastypeIsbandgivesthemagnituderangeas9.4–10.6photographicmagnitude,andspectral typeK5III.Laterobservationshavere-classified thespectrumasM0III(Henryet al.2000).

2. New observations

V538 Cas is, at 7.7V, a bright star. It is thus a suitable object for theAAVSOBrightStarMonitor (BSM;AAVSO2009).This instrumentaimsatfillinganicheincurrentphotometrictelescopeecologywherenotmanyCCD-equippedtelescopesareoperating:thereareinterestingstarsthataredifficulttoobserveusingmostmoderntelescopesbecausethestarsaretoobrightandrisksaturatingtheCCDdetector.Findingsuitablecomparisonstarsforbrightstarsintelescopeswithsmallfieldsofviewcanalsobeachallenge.Severalof thecurrentphotometric surveys, suchasNSVSandASAS,onlymeasurestarsfainterthanabouteighthmagnitude,givingmuchroomforworkforaninstrumentsuchastheBrightStarMonitor.TheBSMisa6-cmf /6.2refractorwithaSBIGST-8XMECCDwitha fieldofviewof84'×127',operated forAAVSObyTomKrajciattheAstrokolkhozfacilityinNewMexico. 30-second (V)and60-second (B)exposuresofV538Caswereobtained

Holmberg, JAAVSO Volume 40, 2012 987

withtheBSMonninenightsduringthreeweeksinNovemberandDecember2011.Theimageswereanalyzedusingvphot(AAVSO2011)andthebrightnessofthestarmeasuredrelativetoanensembleoffivestars.Theresults(Table1)showverysmallornosignificantvariationsduringthistimeinterval. These observations are in line with other measurements from the post-photographicera.AphotometricstudybyHenryet al.foundslightshort-timescalevariationsontheorderofahundredthofmagnitude(Henryet al.2000).Hipparcos(Perrymanet al.1997)consistentlymeasuredV538Casaround7.75withvariationsontheorderofhundredthsofamagnitude.TASS,TheAmateurSkySurvey (2012),observed the staron fouroccasionsduring threeweeks,findingaconstantbrightness,alsointhevicinityof7.75.Togetherwiththenewobservationsreportedhere,thisleadsthepresentauthortoconcludethatV538Cas,atleasttoday,doesnotshowthetypeofvariationsonceattributedtoit.

3. Discussion

Althoughnottheprimarypurposeofthisshortcommunication,anattemptwillalsobemadetotrytoresolvethediscrepancybetweendatashowingrapidvariationsontheorderof0.6magnitudeormore,anddatashowingnoorverysmallvariationsinthestarknownasV538Cas. Onepossibilityisofcoursethatthisstarhaschangeditsbehaviorsincethemid-20thcentury.AnotheristhatWeber’sinitialguess,thatthisisanEAstar,iscorrectandthatfurthereclipseshavenotbeencoveredintheobservationsmadewiththeBSM,Hipparcos,TASS,andbyHenryet al.Butcantherebeanotherexplanation? Asimilardiscrepancyfound in the literaturemayprovideaclue.Weber,also in1958,publishedhisdiscoveryofaCepheid in theopenclusterNGC7789,varyingbetweenphotographicmagnitude11.2and12.2.Thediscoverywas confirmed by another observer, Romano (Weber 1958b). Cepheids inopen clusters have great astrophysical importance, andWeber’s finding wastherefore followed up. Burbidge and Sandage found no variations at all inthe star in their photographic photometry of the cluster using the 100-inchHooker telescope (Burbidge and Sandage 1958). Furthermore, Starrfield’sphotoelectricmonitoringofthestarwitha24-inchreflectoratLickduringthreehourspernightduringthreenightsfoundnovariationsinthestar.Photographicphotometryonaseriesofplatestakenwiththe20-inchCarnegieastrographatLickgaveasimilarresult:constantbrightness(Starrfield1965).MeasurementsonplatesfromtheHarvardCollegeObservatoryplatearchivesgaveasimilarresult(Janes1977). Thus,wehavetwocases inwhichWeberfoundvariationsofquite largeamplitude,bothofwhichwerefirstconfirmedbyanotherobserverusingsimilartypeofcameras(Weberusedsmall-scalephotographiccameras)thatwasnotconfirmedbylaterobservers.Starrfield,intryingtoresolvethisdiscrepancy,

Holmberg, JAAVSO Volume 40, 2012988

pointedoutthatapossiblesolutioncouldbethesmallplatescaleofWeber’scamera; thesuspectedvariablestarwasthereforeimperfectlyseparatedfromanother star, and seeing variations could produce a spurious impression ofvariability(Starrfield1965).PerhapsthisorsomeotherphotographiceffectcanaccountforthevariationsfoundinV538CasbyWeberandHäussler.

4. Acknowledgements

The author wishes to thank AAVSO Director Arne A. Henden for hisgenerous support.This research has made use of the simbad database (CDS2007),operatedatCDS,Strasbourg,France.

References

AAVSO2009,TheBrightStarMonitor(www.aavso.org/bsm).AAVSO2011,vphotonlinephotometricanalysistool(www.aavso.org/vphot).Burbidge,E.M.,andSandage,A.1958,Astrophys. J.,128,174.CentredeDonneesastronomiquesdeStrasbourg2007, simbadAstronomical

Database,http://simbad.u-strasbg.fr/simbad/Häussler,K.1974,Inf. Bull. Var. Stars,No887,1.Henry,G.,Fekel,F.,Henry,S.,andHall,D.2000,Astrophys. J., Suppl. Ser.,

130,201.Janes,K.A.1977,Astron. J.,82,35.Perryman,M.A.C.,EuropeanSpaceAgencySpaceScienceDepartment,and

theHipparcosScienceTeam1997,The Hipparcos and Tycho Catalogues,ESA SP-1200, ESA Publications division, Noordwiijk, The Netherlands(Hipparcos data on V538 Cas accessed using http://www.rssd.esa.int/hipparcos_scripts/HIPcatalogueSearch.pl?hipepId=6084).

Samus,N.N.,et al.2011,General Catalogue of Variable Stars,onlineversion(http://www.sai.msu.su/gcvs/gcvs/index.htm), Sternberg Astron. Inst.,Moscow.

Starrfield,S.1965,Publ. Astron. Soc. Pacific,77,206.TheAmateurSkySurvey(TASS)2012,http://sallman.tass-survey.org/servlet/

markiv/template/TassPlot.vm?object_id=6293418Weber,R.1958a,J. Obs.,41,74.Weber,R.1958b,Astronomie,72,80.

Holmberg, JAAVSO Volume 40, 2012 989

Table 1. Bright Star Monitor measurements of V538 Cas in November–December2011. JD Magnitude filter

2455881.85384 9.422 B 2455881.85444 7.696 V 2455882.80720 9.433 B 2455882.80782 7.715 V 2455888.78655 9.422 B 2455888.78714 7.713 V 2455889.68596 9.455 B 2455889.68656 7.699 V 2455892.65948 9.429 B 2455892.66008 7.715 V 2455893.65671 9.425 B 2455893.65730 7.718 V 2455894.67079 9.435 B 2455894.67139 7.702 V 2455895.65212 9.404 B 2455895.65272 7.697 V 2455896.64828 9.399 B 2455896.64888 7.706 V

Boyd, JAAVSO Volume 40, 2012990

A Practical Approach to Transforming Magnitudes onto a Standard Photometric System

David Boyd5 Silver Lane, West Challow, Wantage, OX12 9TX, UK; [email protected]

Received December 30, 2011; revised March 15, 2012; accepted April 5, 2012

Abstract We describe a practical implementation, convenient for amateuruse, of a method of transforming instrumental magnitudes onto a standardphotometricsystemindifferentialCCDphotometry.

1. Introduction

MostamateurastronomersusingaCCDcameratomeasurethebrightnessofanobjectofinterest,beitavariablestar,anasteroid,orsomeotherdistantlight source, employ a procedure called differential photometry. In this themagnitudeof the targetobject is foundbycomparing itsbrightness tootherstarsinthesamefieldofviewwhosemagnitudesareknown.Themeasureofanobject’sbrightness foundby integrating the imageof theobject recordedby the CCD is called its instrumental magnitude. Increasingly amateurs arebeingencouraged toobserveusingphotometric filtersand to transformtheirmeasured instrumental magnitudes onto one of the standard photometricmagnitudesystems. Transforminginstrumentalmagnitudesinthiswaygreatlyincreasestheirusefulness for scientific analysis. They can be combined with similarly-transformed measurements from other observers into a single internally-consistentdataset.ThemostcommonstandardphotometricsysteminusebyamateurstodayistheJohnson-CousinsUBVRIsystemanditisthiswhichweshallusehere,inparticularitsBVRI subset.However,theapproachdescribedisapplicabletoanystandardsystem. There are two main reasons why instrumental magnitudes differ fromstandard magnitudes: atmospheric extinction and a mismatch between theresponseoftheequipmentinuseandthestandardsystem.Byobservingstarswhose magnitudes are very accurately known (“standard” stars), correctionscanbefoundwhichenableinstrumentalmagnitudestobetransformedontothestandardsystem.Overtheyearsseveralformulationsofthesetransformationshavebeendevisedandpublished,usuallywiththeexpectationthatphotometricskieswillbe readilyavailable for theiruse.Wedescribehereavariationonpreviously published methods which amateurs may find better suited toconditionstheyarelikelytoexperience. Firstweexplainhowatmosphericextinctionandinstrumentalcharacteristicsaffectobservationsandbrieflydiscussthescopeofapplicabilityoftheproposed

Boyd, JAAVSO Volume 40, 2012 991

approach.Nextwedescribethetransformationequationsanddiscusschoosingstandard stars. We then explain how to find the transformation parametersandusethemtotransforminstrumentalmagnitudesandcolorindices.Finallywe use measurements of Landolt standard fields to illustrate the benefits oftransforminginstrumentalmagnitudes.

2. Atmospheric extinction and instrumental transformation

Atmosphericextinctionhastwoprincipalcauses:scatteringofincidentlightbyaerosolsincludingdustandwatervapor,andmolecularRayleighscattering.Aerosolscattering is relativelyuniformacross thespectrum,risingslowlyatshorterwavelengths,and is thedominantcauseofextinctionatwavelengthslongerthanabout500nm.Rayleighscatteringincreasesveryrapidlyatshorterwavelengths anddominates at theblue endof the spectrum.The amount ofaerosol scattering can vary widely depending on the aerosol content of theatmosphere,whereasRayleighscatteringremainsrelativelyconstant.Furtherinformationabout atmospheric extinctioncanbe found in (Green1992) and(Stubbset al.2007). Wavelength-independentscatteringisrepresentedbyafirstorderextinctioncoefficientmultipliedbytheairmassinthedirectionofthestar,andwavelength-dependentscatteringbytheproductofasecondorderextinctioncoefficient,theairmass,andthecolorindexofthestar.Sincefirstorderextinctionisprimarilycausedbyaerosolscatteringitcanpotentiallychangerapidlyduringasinglenightorfromnighttonightasthedustormoisturecontentoftheatmospherechanges.SecondorderextinctionismainlyduetoRayleighscatteringandisgenerallyconsideredtobestableovertimeatagivenlocation.BecauseoftherapidriseinRayleighscatteringattheblueendofthespectrum,secondorderextinctionshouldprimarilyaffectmeasurementsmadethroughaBfilterwhilemeasurementsthroughV,R,andIfilterswillbemuchlessaffected. Thepresenceofa thinlayerofcloudorhazereducestheincominglightequally at all wavelengths, as verified experimentally (Honeycutt 1971). Inpracticethisaddsaconstant“gray”termtoatmosphericextinction,whichhastheeffectofchangingtheimagezeropoint.Thincloudisoftendifficulttodetectvisuallybutitspresenceneednotpreventgoodqualityphotometryprovideditisuniformandstable(Hardie1959).Nevertheless,themostreliableresultswillalwaysbeobtainedunderclearskies. InpracticeallBVRIfilterandCCDdetectorcombinationsdifferintheirspectral response from the standard Johnson-Cousins system. This meansthattheywillproduceresultswhichdifferfromthestandardsystemandthisdifferencewillvarywith thecolorof thestar.Since themismatch isusuallysmall,itisnormallyassumedthatitcanbecorrectedbyalineartermcomprisingtheproductofaninstrumentaltransformationcoefficientandthecolorindexofthestar.Providedtheinstrumentalcomponentsdonotchange,anychangein


the transformation coefficient, for instance due to long term changes in thetransmission properties of the optical components and filters, is likely to besmallandslow. So,whilefirstorderextinctionmaychangefromnighttonight,andevenduringasinglenightasatmosphericconditionschange,anychangesinsecondorderextinctionatthesamelocationandinstrumentaltransformationwiththesameequipmentarelikelytohappenonlyslowlyovertimeasnotedinWelch(1979)andHarriset al.(1981).Itwouldneverthelessbeprudenttoremeasurethematregularintervalstomonitorforanysuchchange.

3. Applicability

The approach to obtaining transformation parameters described here isaimedatthoseusingCCDcamerastoimagetheskythroughsufficientlylongfocal length optical equipment that the field of view is small, typically lessthan one degree across. In photometry it is normally good practice to workaboveanaltitudeofabout30degrees,corresponding toanairmassof2, toavoidtheworsteffectsofatmosphericextinction.Underthesecircumstanceswecanassumethatallstarsbeingmeasuredinthesameimageareatthesamezenithdistanceandhencearemeasuredthroughthesameairmass.Theerrorintroducedbythisassumptionis,intheworstcase,onlyafewthousandthsofamagnitude.Itshouldbenotedhoweverthatundersomecircumstances,forexamplewhenimaginglargefieldsusingDSLRcamerasorimagingclosetothehorizonwhereairmassincreasesrapidlywithreducingaltitude,itmaynotbevalidtoassumethatallstarsintheimagehavethesameairmassandamorerigorousanalysismustbecarriedout.

4. The transformation equations

Wetakeasourstartingpointthefollowingequationswhichareconventionallyusedtotransforminstrumentalmagnitudes(inlowercase)intomagnitudesinastandardphotometricsystem(inuppercase),seeforexampleDaCosta(1992)andWarner(2009).

B=b–k'bX–k"bbvX(B–V)+Tbbv(B–V)+Zb (1)

V=v–k'vX–k"vbvX(B–V)+Tvbv(B–V)+Zv (2)

whereBandVarethestandardB-andV-bandmagnitudesofthestar,bandvaretheinstrumentalmagnitudesofthestarmeasuredinBandVfilters,k'bandk'varetheB-andV-bandfirstorderextinctioncoefficients,k"bbvandk"vbvaretheB-andV-bandsecondorderextinctioncoefficientsforthe(B–V)colorindex,Xistheairmassofthestar,TbbvandTvbvaretheB-andV-bandinstrumentaltransformationcoefficients for the (B–V)color index, andZbandZvare the


B-andV-bandimagezeropointswhichareofcoursethesameforallstarsinanimage. Weadopttheconventionthatthefirst,oronly,letterinasubscriptindicatesthefilterpassband,whilethesecondandthirdlettersindicatetherelevantcolorindex. As we noted earlier, rapid atmospheric changes may cause first orderextinction coefficients and image zero points to vary from image to image,whereassecondorderextinctionandinstrumentaltransformationcoefficientsshouldremainconstantorchangeonlyslowlyovertime. The first order extinction, second order extinction, and instrumentaltransformationcoefficientshaveusuallybeendeterminedbyseparateprocesses.ThetwocommonmethodsoffindingtheextinctioncoefficientsaretheBouguerandHardiemethods.TheBouguermethodinvolvesfollowingaclosegroupofstandardstarsastheymovethroughawiderangeofairmassoverthecourseofanight.TheHardiemethodrequirescloselytimedobservationsofpairsofredandbluestandardstarsatwidelyseparatedairmasses.Bothmethodsdependonatmosphericextinctionremainingconstantoverthewiderangesoftimeand/ortheskyinvolvedinmakingthesemeasurements.Instrumentaltransformationcoefficientsarefoundbyobservingacloselyspacedgroupofstarswithawiderangeofcolorsatlowairmass.Descriptionsofthesemethodscanbefoundin,forexampleWelch(1979)andRomanishin(2002). However,aspointedoutin(Harriset al.1981),determiningtheseparametersseparately in thisway is sub-optimalandusually requires iteration toobtainthebestsolution.Theyarguethat it isbetter tomakeuseofallobservationstogether to determine the required parameters. Our approach is a simplifiedversionofthatdescribedbyHarriset al.whichmeetstheneedsofdifferentialCCDphotometryandmaybeeasierforamateurstoimplementinpractice.Ithasthemeritofreachingasolutioninstageswithgraphicalverificationateachstageratherthana“black-box”multilinearleastsquaresapproach.Thismakesiteasiertospotproblemswithindividualstars,internalinconsistencieswithinthedata,orhumanerror. Wecanrearrangeequations(1)and(2)asfollows:

(B–b)=Tbbv(B–V)–k"bbvX(B–V)+Zb–k'bX (3)

(V–v)=Tvbv(B–V)–k"vbvX(B–V)+Zv–k'vX (4)

andthenrewritethemas:

(B–b)=Cbbv(B–V)+Z'b (5)

(V–v)=Cvbv(B–V)+Z'v (6)

whereCbbv=Tbbv–k''bbvXincorporatestheB-bandinstrumentaltransformationandsecondorderextinctioncorrectionfor the(B–V)colorindex,Cvbv=Tvbv–k''vbvXisasimilartermfortheV-band,Z'b=Zb–k'bXincorporatestheB-band


imagezeropointandfirstorderextinctioncorrection,andZ'v=Zv–k'vXisasimilartermfortheV-band. SinceweareworkingwithsmallfieldsandcanassumeallstarsintheimagebeingmeasuredhavethesamevalueofairmassX,thetermsCbbv,Cvbv,Z'b,andZ'varethesameforallstarsintheimage.Ifweplot(B–b)against(B–V)forallstarsinanimage,thegradientwillgiveusCbbvatthevalueofXforthatimage,andsimilarlyplotting(V–v)against(B–V)givesCvbv. Similar equations to (5) and (6) relatemagnitudesmeasuredusingotherfiltersandcolorindices.Forexample:

(R–r)=Crvr(V–R)+Z'r (7)

(I–i)=Civi(V–I)+Z'i (8)

wheredefinitionsof the termsCrvr,Civi,Z'r, andZ'i followbyanalogywiththoseabove. Hence, if we can measure values of Cbbv, Cvbv, Crvr, and Civi (henceforthdescribedcollectivelyas theCparameterswhere,generically,C=T–k''X),eachwiththecorrespondingvalueofX,thenwecandeterminetheinstrumentaltransformationsTandsecondorderextinctioncoefficientsk''.Asweshallsee,thesearetheparametersrequiredtotransformdifferentialCCDphotometry.

5. Sources of standard stellar magnitudes

Inordertomeasuretheseparameters,weneedtoidentifygroupsofstarswhich(a)willfitwithinasmallCCDfieldofview,(b)containasmanystarsaspossiblewithaccuratelyknownmagnitudesineachofthefilterpassbands,and(c)spanaslargearangeofcolorindexaspossible. Traditionally, the gold standard for calibration is the set of equatorialstandardstarsmeasuredovermanyyearsbyArloLandolt,seeLandolt(1992,2009,2011).Thesehavearootmeansquare(rms)Vmagnitudeuncertaintyofabout0.004mag.WhileLandolt standard starshave the advantageofbeingvisiblefromalllatitudes,forobserversfarfromtheterrestrialequatortheydonotriseveryhighintheskyandsotraversearelativelysmallrangeofairmass.Using only those standard stars would necessitate extrapolating to air massvaluesoutsidethisrange,aprocedurewhichwouldinevitablyreduceaccuracy.UsingonlyLandoltstarsthereforelimitstheaccuracyattainablewhentryingtoaccountforairmassdependenteffects.AnotherslightdrawbackofLandoltstarsisthatitissometimesdifficulttoincludemanyofthemwithawiderangeofcolorindexwithinatypicalCCDfield. For this reasonwe investigatedusinggroupsofsecondarystandardstarswhichhavethemselvesbeencalibratedusingLandoltstars,inparticularoneswhichculminatenearthezenithathigherlatitudesandcanthereforebeobservedatornearanairmassof1.SuitablefieldsofstarshavebeenmeasuredintheB,


V,R,andIpassbandsbyArneHendenasanaidtoselectingcomparisonstarsforvariablesandareavailablefromHenden(2012).Whenselectingstarsfromthesefieldstouseassecondarystandards,weexcludedthosewhichhadfewerthan tenobservations, largemeasurementuncertainties,orclosecompanionswhichmight compromise theirmeasurement.Also, stars significantlyoutoflineinmagnitude-colorplotswiththemajorityofstarsinthesamefieldwereexcludedonthegroundsthattheirmagnitudesmaybeincorrectortheymightbevariable.Thetenbrighteststarsineachfieldsatisfyingtheseselectioncriteriahavebeenused.ThemagnitudeuncertaintiesofthesestarsarelargerthanforLandoltstandardstars,butthisisinpartcompensatedbyhavingmorestarsperfieldwithawiderrangeofcolor.ThestarsusedintheexamplegivenherewerefromfieldsaroundthevariablesEECep,TTCas,V504Per,andVarCas06(alsoknownasVSXJ000921.8+543943—thebrightgravitationalmicrolensvariable). Figure1showsstarsinthefieldofVarCas06.ThecircledstarswereusedassecondarystandardsandhaveVmagnitudesintherange11.373–13.889withrmsuncertainty0.024andB–Vcolorindicesintherange0.125–1.716. TheavailabilityofaccuratelymeasuredstellarmagnitudesacrossmuchoftheskyfromphotometricsurveyssuchastheAAVSOAPASSsurvey(AAVSO2012)shouldgreatlyincreasetheavailabilityofhighqualitysecondarystandardstarssuitableforthispurpose.

6. Finding the instrumental transformation and second order extinction coefficients

First we select a suitable field containing stars with known, accurately-measured B, V, R, and I magnitudes covering as wide a range of colors aspossible,suchastheoneshowninFigure1.Weidentifythestarsinthefieldweintendtouseasoursecondarystandards.Wethenwaitforaclearnightwithstableskyconditionswhenthefieldiswellplacedandtakebetweenfiveandtenimagesofthefieldthrougheachfilter.Wetakecaretorecordthebrighteststarswithashighsignaltonoiseaspossibleineachfilterwhileavoidingnon-linearity or saturation of the CCD. This typically takes only a few minutesforeachfilterduringwhichwerequiretheskyconditionstoremainclear.Wecalibratetheimagesusingdarkandflatfieldsandusingaperturephotometrymeasure the instrumental magnitudes b, v, r, and i for each of our standardstarsineachimagetakenwiththecorrespondingfilter.Wethencalculatemeanvaluesandstandarddeviationsofb,v,r,andiforeachstaroveralltheimagestakenwitheachfilter.WealsocalculateameanvalueofXofallthestarsinalltheimagestakenwitheachfilter. Tocheckthatskyconditionshaveindeedremainedstablethroughouteachsetofimages,wecancomparestandarddeviationsoftheinstrumentalmagnitudesofeachstarineachfilterwiththeestimatedmeasurementuncertaintiesoutputbythephotometrysoftware.Iftheformeraresubstantiallylargerthanthelatter,


it isan indication thatskyconditionswereprobablyunstableand theresultsshouldnotbeusedforcalibrationpurposes. Weknowvaluesof(B–V),(V–R),and(V–I)andcancalculatevaluesof(B–b),(V–v),(R–r),and(I–i)foreachstandardstar.Wecanalsocalculatetheuncertaintieson(B–b),andsoon,foreachstarbyaddingthequoteduncertaintyon its standard magnitude B and the standard deviation of its instrumentalmagnitudebinquadrature. We plot (B–b) vs (B–V), (V–v) vs (B–V), (R–r) vs (V–R), and (I–i) vs(V–I).Assumingthetransformationsweareseekingarelinear,weexpectthedatapointstolieapproximatelyonastraightline.If thelineishorizontal, itindicatesthatourmeasuredinstrumentalmagnitudehasnocolordependency.If,asismorelikely,thelineisatanangletothehorizontalitmeansthatthereisacolordependencyinourobservationswhichweneedtocorrect. Figure2showsmagnitude-colorplotsof(B–b)vs(B–V),(V-v)vs(B–V),(R–r)vs(V–R),and(I–i)vs(V–I)forstarsinthefieldofthevariableEECep.Theequipmentusedwasa0-35mSCT,SXVR-H9CCDcamera,andAstrodondichroicB,V,R,andIfilters. Fromequations(5) to(8) thegradientsofstraight linesfittedto thedatapointsintheseplotsgivevaluesoftheCparametersatthemeanairmassXcalculated for each filter, and we can calculate their uncertainties from thescatterinthedatapointsaboutthefittedlines. Werepeatthisprocessforseveralmorefieldsofsecondarystandardstarssatisfyingour selectioncriteria andcoveringaswidea rangeof airmass aspossible.EachfieldprovidesvaluesoftheCparametersandacorrespondingvalueofXforeachfilter.Thedatadonotallhavetobecollectedonthesamenightsince,asnotedearlier,theseparametersshouldbestableovertimesodatafromseveralnightscanbecombined. SinceforeachoftheCparameters,C=T–k''X,ifwenowplotthevalueoftheCparameterforeachfilteragainstthecorrespondingvalueofXandmakeweightedlinearfits,wecanobtainvaluesfortheinstrumentaltransformation(T)andsecondorderextinction(k'')coefficientsforeachfilterwithestimatesoftheiruncertainties.InthesefitsweweighteachvalueofCwiththeinversesquareofitsuncertainty. Figure3showsplotsoftheCparametersvsXobtainedfromtwelvesetsofobservationsoffourfieldsimagedovertwonights.AlsoshownintheseplotsarethestraightlinesrepresentingthefitsforTandk''. Table1liststhevaluesoftheinstrumentaltransformationandsecondorderextinctioncoefficientsfoundfromtheseanalyses.Rememberourconventionisthatthefirstletterinasubscriptindicatesthefilterpassband,whilethesecondandthirdlettersindicatetherelevantcolorindex. ThesecondorderextinctioncoefficientsfortheV,R,andIfilterpassbandsare small and consistent with zero within experimental uncertainty. This isas expected given that extinction in these filters is primarily due to aerosol


scattering which has minimal wavelength dependency. Therefore, consistentwith conventional wisdom, we will assume these have a value of zero.ThesecondorderextinctioncoefficientfortheBfilterissignificantlynon-zeroasexpectedfromtherapidriseinRayleighscatteringatshorterwavelengths. By observing several fields of secondary standard stars covering a widerangeofcolorandairmass,slightdifferencesbetweentheassumed“standard”magnitudes for individual stars and their “true” values are averaged out. Inthiswaywecanoffsettheloweraccuracyinthemagnitudesofoursecondarystandardstarscomparedtoprimarystandards.

7. First order extinction coefficients

Valuesofthefirstorderextinctioncoefficientsk'arenotcalculateddirectlyandarenotneededfordifferentialCCDphotometrywithsmall fieldswhereweassumeXisconstantoverthefield.TheyarecontainedintheimagezeropointsZ'=Z–k'Xineqns(5)to(8).ValuesofZ'canbefoundfrominterceptsofthelinearfitsinFigure2atcolorindex0butingeneralthesewillnotyieldconsistent values of Z and k' since these parameters vary with changes inatmospheric transparency. Nevertheless, if conditions are sufficiently stableduringonenight,wemightexpectZandk'toremainapproximatelyconstant.Inthatcase,ifweplotthevaluesofZ'foreachfilteragainstthecorrespondingvaluesofXfordataobtainedonthatnight,weshouldgetastraightlinewhosegradientgivesthemeanvalueofk'fortheappropriatefilteronthatnight(seeFigure4).Thecorrespondingvaluesofk'arelistedinTable2.Asexpected,k'graduallydiminishesas thewavelength increases, reflecting the reduction inaerosolscatteringatlongerwavelengths.

8. Transforming instrumental magnitudes to standard magnitudes

NowwehavealltheparametersneededtotransforminstrumentalmagnitudesmeasuredindifferentialCCDphotometryontotheBVRIstandardmagnitudesystem. Indoing this it is easier toworkwithequationswhichcontainonlyinstrumentalratherthanstandardmagnitudesontherighthandside.Bysimplemanipulationofeqns(5)to(8)wederivetheequationswerequire.

B=b+C'bbv(b–v)+zb (9)

V=v+C'vbv(b–v)+zv (10)

R=r+C'rvr(v–r)+zr (11)

I=i+C'ivi(v–i)+zi (12)

wheretheC'parametersarerelatedtotheoriginalCparametersasfollows:


C'bbv=Cbbv/(1–Cbbv+Cvbv), (13)

C'vbv=Cvbv/(1–Cbbv+Cvbv), (14)

C'rvr=Crvr/(1–Cvvr+Crvr), (15)

C'ivi=Civi/(1–Cvvi+Civi), (16)

andthevarious“z”termsontherighthandsideareimagezeropointswhicharethesameforallstarsinanimage. Since,generically,C=T–k''XandthevaluesofTandk''areknown(seeTable1),ifweknowtheairmassXofanimagewecancalculatethevaluesoftheappropriateCparametersandhencetheC'parameters. Supposewewant to find the standardVmagnitudeof avariable star inafieldcontainingseveralcomparisonstarswithknownmagnitudes.WetakeseveralimagesofthefieldthroughBandVfiltersandmeasuretheinstrumentalmagnitudesbandvofthevariableandcomparisonstarsineachimage.KnowingthemeanairmassXofthestarsineachimagewecalculateCbbv=Tbbv–k''bbvXand Cvbv =Tvbv – k''vbvX and hence C'vbv from equation (14) for each image.Usingequation(10)andknowingthestandardandinstrumentalmagnitudesforthecomparisonstars,wecandeterminethezeropointzvforeachimage.Sinceweknowthe instrumentalbandvmagnitudesof thevariable,wecanagainuseequation(10)tocalculateitsstandardVmagnitudeineachimage.Finally,usingtheseindividualmeasurementsoftheVmagnitudeofthevariable,wecancomputeitsmeanandstandarddeviation. AsimilarprocedurewillyieldvaluesforB,R,andIcalculatedfromthemeasuredinstrumentalmagnitudesb,v,r,andiusingeqns(9),(11),and(12).

9. Transforming color indices

Thetransformationequationsforcolorindicescanbefoundfromequations(9)to(12).

(B–V)=C'bv(b–v)+zbv (17)

(V–R)=C'vr(v–r)+zvr (18)

(V–I)=C'vi(v–i)+zvi (19)

where

C'bv=1/(1–Cbbv+Cvbv), (20)

C'vr=1/(1–Cvvr+Crvr), (21)

C'vi=1/(1–Cvvi+Civi), (22)


zbv=(zb–zv) (23)

zvr=(zv–zr) (24)

and

zvi=(zv–zi). (25)

Herethetwosubscriptlettersindicatetherelevantcolorindex.

10. Implementation

Inpractice,thetwoproceduresdescribedabove—findingthetransformationparametersandusingthemtotransforminstrumentalmagnitudestostandardmagnitudes—arequitestraightforwardtoimplementinaspreadsheet.

11. Transforming magnitudes measured for Landolt standard fields

Asanapplicationofthisapproach,BVR-filteredinstrumentalmagnitudeswere measured for stars in three Landolt standard fields and transformedas described above. The rms residuals between the standard and derivedmagnitudesbeforeandaftertransformationareshowninTable3.Theseresultsclearlyshowtheimprovementachievedbytransformingmagnitudesontothestandardsystem.

12. Conclusion

Wehavedescribedanddemonstratedapracticalapproachtofindingandapplying the transformations required tobring instrumentalmagnitudesontoastandardphotometricsystemindifferentialCCDphotometry.Thisincludescorrecting for second order atmospheric extinction where appropriate. It ispossible to use well-measured secondary standard stars in fields spanning awiderangeofdeclinationstoenablefullcoverageoftheairmassrangefromobservingsitesfarfromtheterrestrialequator.Skyconditionsmustremainclearandstableforlongenoughtoobtainshortseriesoffilteredimagesofthefieldsrequiredtocovertherequiredrangeofairmass.Theseimagescanbeobtainedonseveralnightsand theresultscombined.Thisapproachmaybeeasier forsomeobservers,particularlythoseoperatingathighterrestriallatitudes,tousethanotherapproaches.


IamgratefultoDr.ChrisLloydandDr.RichardMilesforhelpfulsuggestionsinpreparingthispaperandtoBrianWarnerforstimulatingmythoughtsonthissubject. Constructive comments from an anonymous referee have helped toclarifyandimprovethepaper.


References

AAVSO.2012,APASS:TheAAVSOPhotometricAll-SkySurvey(http://www.aavso.org/apass),AAVSO,Cambridge,MA.

Da Costa, G. S. 1992, in Astronomical CCD Observing and Reduction Techniques,ed.S.B.Howell,Astron.Soc.Pacific,SanFrancisco,90.

Green,D.W.E.1992,Int. Comet Q.,14,55.Hardie,R.1959,Astrophys. J.,130,663.Harris, W. E., Fitzgerald, M. P., and Reed, B. C. 1981, Publ. Astron. Soc.

Pacific,93,507.Henden,A.H.2012,“Calibrationfields”(ftp://ftp.aavso.org/public/calib/).Honeycutt,R.K.1971,Publ. Astron. Soc. Pacific,83,502.Landolt,A.1992,Astron. J.,104,340.Landolt,A.2009,Astron. J.,137,4186.Landolt,A.2011,“Equatorialstandards”(http://www.cfht.hawaii.edu/ObsInfo/

Standards/Landolt/).Romanishin, W. 2002, “An Introduction toAstronomical Photometry Using

CCDs”(http://homepage.usask.ca/~ges125/Astronomy/wrccd4a.pdf).Stubbs,C.W.,et al.2007,Publ. Astron. Soc. Pacific,119,1163.Warner,B.2009,PhotometryWorkshop,Soc.Astron.Sciences,28thAnnual

SymposiumonTelescopeScience,heldMay19–21,2009,BigBearLake,CA.Welch,D.1979,J. Roy. Astron. Soc. Canada,73,370.

Transformation Second Order Coefficients Extinction Coefficients

Tbbv 0.0295±0.0104 k"bbv –0.0199±0.0067 Tvbv –0.0335±0.0091 k"vbv 0.0016±0.0055 Trvr –0.1262±0.0164 k"rvr –0.0077±0.0102 Tivi –0.0642±0.0165 k"ivi 0.0019±0.0095

Table1.Instrumentaltransformationandsecondorderextinctioncoefficients.

First Order Extinction Coefficients

k'b 0.376±0.015 k'v 0.245±0.016 k'r 0.224±0.025 k'i 0.166±0.029

Table2.Firstorderextinctioncoefficientsfordataobtainedononenightunderstableconditions.


Table3.rmsresidualsbetweenstandardandderivedB,V,andRmagnitudesbeforeandaftertransformationforstarsinthreeLandoltstandardfields. Field Air mass rms residuals between standard and derived magnitudes

untransformed transformed B V R B V R

98-185 1.63 0.064 0.028 0.033 0.021 0.008 0.008 98-618 1.64 0.035 0.026 0.055 0.015 0.007 0.008 114-750 1.57 0.031 0.018 0.031 0.009 0.007 0.009 Mean — 0.043 0.024 0.040 0.015 0.007 0.008

Figure1.StarsinthefieldofVarCas06usedassecondarystandards.

Figure2.(B–b)vs(B–V),(V–v)vs(B–V),(R–r)vs(V–R)and(I–i)vs(V–I)forstarsmeasuredinthefieldofthevariableEECep.


Figure 4. Z'b, Z'v, Z'r, and Z'i vs X for the data from one night under stableconditions.

Figure3.Cbbv,Cvbv,Crvr,andCivivsXfor12setsofobservationsoffourfieldsimagedovertwonights.

Hambsch, JAAVSO Volume 40, 2012 1003

ROAD (Remote Observatory Atacama Desert): Intensive Observations of Variable Stars

Franz-Josef HambschOude Bleken 12, B-2400 Mol, Belgium; [email protected]

Presented at the 101st Spring Meeting of the AAVSO, Big Bear Lake, CA, May 22–24, 2012

Received August 23, 2012; revised October 1, 2012; accepted October 2, 2012

Abstract

The author discusses his new remote observatory under pristine skies andthe intensive observations of variable stars he is accomplishing. The starsunderinvestigationaremainlycataclysmicvariables,observedinresponsetoAAVSO,CBA,andVSNETalerts;othertypes,suchasRRLyraestars,werealso observed. Examples are presented of dense observations of differentcataclysmicvariablesaswellasanRRLyraestar.Featuredisthefirstbrightoutburst of SVAri (NovaAri1905) since its discovery, as well as the firstoutburstofUGWZcandidateBWScl.ResultsforVWHyi,anothercataclysmicvariable,willalsobeshown.Furthermore,anintensivelyobservedRRLyraestarwillbehighlighted.

1. Introduction

Itisanamateurastronomer’sdreamtoobserveunderpristinedarkandclearskiesnearlyeverynight likeat thesiteswhere theprofessionalastronomicalobservatoriesarelocated.Suchadreamnormallynevercomestrue.However,modern techniques and infrastructures in most countries make it possiblenowadays to observe from remote sites using off-the-shelf technology. TheauthorinstalledaremoteobservatoryunderthedarkskiesoftheAtacamaDesertclosetothetownofSanPedrodeAtacama,Chile.ThetelescopeishousedatSPACE (San Pedro deAtacama Celestial Exploration (http://www.spaceobs.com/index.html)).Theowner,alsoanamateurastronomer,formerlyworkedattheEuropeanSouthernObservatory(ESO)atthebigtelescopesitesinChile.In2003hestartedSPACE,whichhasbeenextendedtotelescopehostingforthelastcoupleofyears.Icontactedhimin2009anddecidedtoestablishmyobservatoryathisplace. Unfortunately,deliveryofthetelescopetookmuchlongerthananticipated,andonly in July2011was I able to install thedome,mount, and telescope.SinceAugust1,2011,theremoteobservatoryhasbeenproducingdataeveryclearnight.Sofar,inlessthan8.5monthsofoperation,thisamountedtoabout220data-takingnights.Notbad,isitnot?

Hambsch, JAAVSO Volume 40, 20121004

IamcollaboratingontheobservationofcataclysmicvariablestarswithJ.PattersonoftheCenterforBackyardAstrophysics(CBA)andT.KatooftheVSNETemailalerts.SinceIamalsointerestedinobservingRRLyraestars,IcollaboratewiththeGroupeEuropéend’ObservationsStellaires(GEOS).InBelgium,IamamemberoftheWerkgroepVeranderlijkeSterren(WVS)onHighAmplitudeDeltaScuti(HADS)stars.IamalsomemberoftheAAVSOand the German Bundesdeutsche Arbeitsgemeinschaft für VeränderlicheSterne(BAV). During themanyclearnights Igathera lotofdataonmanystars.Sincespace here is limited, I restrict myself to some highlights: the outbursts ofSVAri,BWScl,andVWHyi;andIalsolookatanRRLyrae-typestarwithastrongBlazhkoeffect.

2. Observatory

The remote observatory in Chile houses a 40-cm f /6.8 Optimized Dall-Kirkham(ODK)fromOrionOptics,England.TheCCDcameraisfromFingerLakesInstruments(FLI)andcontainsaKodak16803CCDchipwith4k×4kpixelsof9mmsize.ThefilterwheelisalsofromFLIandcontainsphotometricBVIfiltersfromAstrodon. Figure1showsanimageoftheremotetelescopeinChile.Itishousedinaclamshelldome,makingeasymovementof the telescopepossiblewithouttheneedtofollowwithashutterofanormaldome.Imagesofanight’ssessionare either acquiredwith acp or ccdcommander automation software. Furtheranalysisintermsofdeterminationofthebrightnessofthestarsisdoneusinga program developed by P. de Ponthierre (2010). The data are then finallysubmittedtotheAAVSO.3. SV Arietis (Nova Arietis 1905)

As a first example, I show the results of the campaign on SV Arietis(NovaAri1905).SVAriwasdiscoveredonNovember6,1905,byM.andG.Wolf(1905)inHeidelberg,Germany,ataphotographicmagnitudeof12.0.Itwasreportedthatithadbrightenedfrommagnitude22.1.HimpelandJantsch(1943)reportedapossiblesightinginSeptember1943,atamagnitudeof15.7,butthiswasnotconfirmed.Nobrightnessincreasehasbeenobservedforthisstareversince. Then,on2011August2.788UT,R.StubbingsobservedthefieldofSVAriandsawanobjectatmagnitude15.0.Hesentanalertviathemailinglistcvnet-outbursttoaskforconfirmation.TheoutburstinformationwasalsogivenviatheVSNETmailinglist.ThisleadtotheconfirmationbyG.Masi(2011)andR.Fidrich(2011).IsawthosealertsviaVSNET,andsinceG.Masiimmediatelytookatimeseriesandobservedsuperhumps,Ialsodecidedtogoafterthisstar


andstarteda timeseriesatAugust2.844UT,just1.34hoursafter theinitialdiscovery.AfirstanalysisofthedataofG.MasibytheKyototeam(Ohshimaet al.2011)showedthatthestarisprobablyanSUUMatypedwarfnovawithasuperhumpperiodofabout1.54hours.Thepresentoutburstseemsalsonotasbrightastheoneduringthediscoveryofmagnitude12.However,anothermailfromT.Kato(2011a)onVSNETreportedthatprobablytheoriginalbrightnessestimatewastoooptimisticasitseemsthatmanybrightnessdeterminationsofM.Wolfwereabout2magnitudestoobright. Figure2showstheobservationsImadeofthisstaroveraperiodofmorethantwoweeks.Duringthisperiodthestardroppedmorethanonemagnitudeinbrightness.Figure2alsoclearlyshowsindividualnightlybrightnessvariationsofabout0.3magnitude. Figure 3 shows the time series observation made during the first night.Clearly a superhump of 0.3 magnitude is visible. The magnitude of thesuperhumpsreducedtoabout0.15magnitudeafteracoupleofdays. BasedontheanalysisbytheKyototeam,therehavebeendistinctstagesintheevolutionofsuperhumpsinSVAri.ThemeanperiodbeforeAugust4was0.05574(18)daywhichsincethenshortenedto0.05519(5)day.Also,laterdatashowedthatSVAriwasgraduallydeclining(~0.05mag./day).ThisseemedveryslowforanordinarySUUMatypedwarfnova.Thus,thisobjectmightbeaWZSge-typedwarfnova.Thisinformationisbasedone-mailexchangesviaVSNET.Towards the end ofAugust 2011, SVAri had dimmed towardsmagnitude18.

4. BW Sculptoris

AnotherexampleofanintensivelyfollowedstarisBWSculptoris,whichwentintoitsfirst-everobservedoutburston2011October21.BWSclisalsoacataclysmicvariablestar.OnthesamedaytheAAVSOSpecial Notice #261(AAVSO 2011a) was published mentioning the outburst of BW Scl. It wasvisually observed by M. Linnolt on October 21.3146 at a magnitude of 9.6(visual).TheoutburstwasconfirmedbyA.Plummeratmagnitude9.4(visual).ThestarhasconflictingclassificationsintheliteratureandisprobablyaWZSge-typedwarfnova.OnOctober25, theAAVSO Alert Notice 449 (AAVSO2011b)wasissuedconcerningthisoutburst. Ihadalreadybeen follwing this star in itspre-outburstphase.However,Imissed theoutburst, as I thought the starwasnotdoingmuch,andceasedobserving it on October 14—just a week before the outburst took place. Ofcourse, I restarted observations immediately after the news was spread andfollowedthestaroveraperiodof2.5months.Figure4showsthedevelopmentofthebrightnessoverthefullobservingperiod. Afterafewdaysnicesuperhumpsofabout0.25magnitudedeveloped,ascanbeseen inFigure5.Afteraweek into theoutburst theearlysuperhump


periodwasdeterminedtobe0.054308(3)daybyKato(2011b).Afterarapiddecliningphasefrommagnitude11.7toaboutmagnitude14,nicesuperhumpsof0.3magnitudedeveloped,beginningataboutJD2455877.

5. VW Hydri

At the request of professional astronomers from SouthAfrica (P.Woudt(2011)),IbeganobservationsofVWHyijustasthestarwentintosuperoutburst,althoughthatwasasurprisetothepros,asthesuperoutburstwasnotexpectedyet.Myobservationstriggeredsatelliteobservationsofthestar. VWHyiisapopularcataclysmicvariableintheSouthernsky.Manystudieshavebeenperformedon this star; see, for example,AAVSO (2010).Duringquiescencethestarisatmagnitude14.4,Normaloutburstshappenonaverageevery27.3daysandlastabout1.4days.Thesuperoutbursthappensonaverageevery179daysandlastsforabout12.6days.Figure6showsimpressivelythisbehaviorofVWHyiwithonesuperoutburstandtwonormaloutbursts. ThestardevelopsstrongsuperhumpsduringitsoutburstascanbeseeninFigure7.Thevariationofthosehumpsreaches0.5magnitude.

6. Example of an RR Lyr star, V1820 Ori

Thistypeofvariableisnamedaftertheprototype,thevariablestarRRLyraeintheconstellationLyra.RRLyrstarsarepulsatinghorizontalbranchstarswithamassofaboutone-halfofourSun’s.Theirperiodisshort,typicallylessthanoneday. MyinterestinobservingRRLyrstarsis,ontheonehand,duetotheshortperiodofthosestars—withinonenightyoucanseequiteachangeinbrightness.On the other hand, the stars also show some brightness modulations, knownas the Blazhko effect. Back in 1907 S. Blazhko observed this effect for thefirsttimeinthestarRWDra(seeSmith2004).TheBlazhkoeffectisnotwell-understood and needs further observational campaigns. Recently due to theKeplerandCoRoTsatellitemissions,more insight into thisphenomenonhasbeengainedasthesatellitescan,ofcourse,observethestarscontinuously,whichis impossible for Earth-bound observations. Nevertheless, observations fromEartharealsoveryvaluable,ascanbeseeninmanypublicationsonthissubjectintheastronomicalliterature.Figure8showsthephasediagramoftheRRLyrstarV1820Ori,whichhasbeenobservedfromChileoverafullseason(morethan3months).Itisobviousfromthefigurethatthelightcurveisnotregular,the maximum brightness is changing over more than 0.5 magnitude, and themomentofmaximumtimeischanging.Soarathercomplexlightcurveistheresult.Presentlythedataareunderanalysis,andIintendtopublishtheresults.


7. Conclusion

The remote observatory under pristine skies in the Atacama Desert ofChileopensupgreatpossibilities toobservevariablestars.Intensivefollow-upobservationsovermanydays,weeks,orevenmonthsarepossibledue tothestableweatherconditions.Thegivenexamplesshowimpressivelywhatispossible.Iwelcomecollaborationsinordertocontributetoscientificresearchofcommoninterest.

References

AAVSO. 2010, Variable Star of the Month (http://www.aavso.org/vsots_vwhyi).

AAVSO.2011a,AAVSO Special Notice #261,AAVSO,Cambridge,MA.AAVSO.2011b,AAVSO Alert Notice 449,AAVSO,Cambridge,MA.dePonthierre,P.2010,LesvePhotometrysoftware(http://www.dppobservatory.

net/AstroPrograms/Software4VSObservers.php).Fidrich,R.2011,e-mailtocvnet-outburst.Himpel,K.,andJantsch,E.1943,Beob.-Zirk. Astron. Nachr.,25,105.Kato,T.2011a,vsnet-alerte-mailmessage13544(http://ooruri.kusastro.kyoto-

u.ac.jp/mailarchive/vsnet-alert/13544).Kato,T.2011b,vsnet-alerte-mailmessage13799(http://ooruri.kusastro.kyoto-

u.ac.jp/mailarchive/vsnet-alert/13799).Masi,G.2011,vsnet-alerte-mailmessage13538(http://ooruri.kusastro.kyoto-

u.ac.jp/mailarchive/vsnet-alert/13538).Ohshima, T., et al. 2011, vsnet-alert e-mail message 13543 (http://ooruri.

kusastro.kyoto-u.ac.jp/mailarchive/vsnet-alert/13543).Smith,H.A.2004,RR Lyrae Stars,CambridgeUniv.Press,Cambridge,103.Wolf,M.,andWolf,G.1905,Astron. Nachr.,169,415.Woudt,P.2011,privatecommunication.


Figure1.PhotooftheremotetelescopeinstallationinChile.

Figure2.LightcurveoftheobservationsofSVArioveraperiodofmorethantwoweeks.Differentcolorsrepresentobservationsduringdifferentnights.

Figure3.LightcurveoftheobservationsofSVArishowingasuperhumpduringonenightofobservation.

Figure4.LightcurveoftheobservationsofBWScloveraperiodofnearlythreemonth.


Figure5.LightcurveoftheobservationsofBWSclshowingseveralsuperhumpsduringonenightofobservation.

Figure6.ObservationsofVWHyiduringsuperoutburstandnormaloutburst.Differentcolorsrepresentobservationsduringdifferentnights.

Figure7.ObservationsofVWHyiduringonenightatthetopofthesuperoutburstclearlyshowingstrongsuperhumps.

Figure8.PhasediagramoftheobservationsofV1820Orioveraperiodofnearlythreemonths.Differentcolorsrepresentobservationsduringdifferentnights.

Price and Paxson, JAAVSO Volume 40, 20121010

The AAVSO 2011 Demographic and Background Survey

Aaron PriceAAVSO Headquarters, 49 Bay State Road, Cambridge, MA 02138;[email protected]

Kevin B. Paxson20219 Eden Pines, Spring, TX 77379; [email protected]


Abstract In2011,theAAVSOconductedasurveyof615peoplewhoareorwererecentlyactiveintheorganization.Thesurveyincludedquestionsabouttheirdemographicbackgroundandvariablestarinterests.Dataaredescriptivelyanalyzedandcomparedwithpriorsurveys.Resultsshowanorganizationofveryhighlyeducated,largelymaleamateurandprofessionalastronomersdistributedacross108countries.Participants tend tobe loyal,with the average timeofinvolvement in theAAVSO reported as 14 years. Most major demographicfactorshavenotchangedmuchover time.However, theaverageageofnewmembers is increasing.Also, a significant portion of the respondents reportbeingstrictlyactiveinanon-observingcapacity,reflectingthegrowingmissionoftheorganization.Motivationsofparticipantsaremorealignedwithscientificcontributionthanwiththatreportedbyothercitizenscienceprojects.Thismayhelpexplainwhyathirdofallrespondentsareanauthororco-authorofapaperinanastronomical journal.Finally, there is someevidence thatparticipationintheAAVSOhasagreater impactontherespondents’viewof theirrole inastronomycompared to thatexpected through increasingamateurastronomyexperiencealone.

1. Introduction

TheAAVSO is a large,multinational citizen scienceorganizationdatingbackto1911.Theorganizationhasexperiencedsignificantchangeinthepasttwodecades(WilliamsandSaladyga2011),yetourlastsurveyofmembershipwasconductedin1994.Astheorganizationbeginsplanningforthefuture,itwastimetousedatatocharacterizethosewhoareactiveandcontributingtotheAAVSO,inallitsforms.Thesedatacanbecomparedwithcurrentassumptionsandbeliefsoftheorganizationandalsousedasatoolforplanningnewinitiativesanddirection.

2. Prior surveys

TheAAVSOhasconductedanumberofmembershipsurveysinthepast35 years. These surveys included a mix of demographic (such as “age”),

Price and Paxson, JAAVSO Volume 40, 2012 1011

programmatic(suchas“observingtrends”)andoperational(suchas“evaluationofstaff”)items. In 1976, AAVSO Director Janet Mattei, with staff members Linda M.Blizzard and Josefa M. Manella, mailed a survey to members. The surveyincludedsectionsonheadquartersoperations,communications,observations,meetings,andpublications.Approximately200–300responseswerereceivedandare stored in theAAVSOarchives (AAVSO1976).However,noknowntabulationorreportoftheresponsesisknowntoexist. InJanuaryof1980,theAAVSOmailedasecondsurveytomembers.Itwasasmallersurvey,withtenquestionsfocusedondemographicsandobservingactivities.AsummaryofresultswerereportedinWaagen(1980).267surveyswerereturnedasofthewritingofthatreport.Noneofthequestionsonthe1980surveywerealsoonthe1976survey,sothetwosurveyscouldbeseenascomplementary. In1994,WayneM.LowderdesignedasurveyofmembersandobserversinresponsetoarequestbyarecentlyconvenedFuturesStudiesGroup.Thesurveyhad 79 items divided into sections focused on demographics, publications,otherresourcesofinformation,astronomicalactivities,observing,headquartersoperations,meetings,anduseofpersonalcomputers.420surveyswerereturnedandtabulatedbyAAVSOstaff(TanjaFoulds,ShawnaHelleur,DennisMilon,and Barbara Silva). Results were presented to the Futures Studies Group inthe form of an executive summary written by Lowder in September 1994,whichexistsintheAAVSOarchives(Lowder1994).TheFuturesStudyGrouppresented results to theAAVSO Council at theAAVSOAnnual Meeting inOctober1994(Hazen1995). TheAAVSOhasalsorunafewsurveysover thepast fewyearsfocusedonmorespecific topics. In2010, theAAVSOconductedasurveywitheightquestions about AAVSO meeting experiences. This survey was distributedexclusively online through theAAVSO website and received 88 responses.Since 2009, theAAVSO’s Citizen Sky project has asked participants a fewoptionaldemographicquestionswhentheyfirstregisteredfortheCitizenSkywebsite.1,385oftheseresponseswereanalyzedinapaperbyPriceandLee(inpress)andsomeofthosedataareincludedhere.

3. Survey design and methodology

The goal of the 2011 survey was to better characterize the AAVSOmembershipsothatstaffandtheCouncilcanmakebetterdecisionsregardingmembershipactivitiesandfuturedirectionsoftheorganization,suchastestingcurrentassumptionsaboutmembersandalsolookingforunexpectedresultsinthedata.Assuch,thesurveyitemsweredesignedtoreportontherespondents’educationalandprofessionalbackgroundsandtheirexperienceintheAAVSOandastronomyingeneral.


The survey was designed prior to the known existence of the previoussurveys.Yet the itemson thesurveysareoftenquitesimilar,whichwefeelisatestamenttothevalidityofthechosenitems.Twentyofthosewhowereprivately invited to take the survey tested the first draft. Only technicalchangescameoutofthatpilottest.Thesurveyhasamaximumof27items(seeAppendixA).However,someitemsareconditionedonlytoappearbasedoncertainresponsestoearlieritemsandallitemswereoptional.Sotheresponseratevariesitem-to-item. The survey was placed on the Survey Monkey website so that resultscouldbeautomaticallytabulated.Wepostedthesurvey’sURLtotheAAVSODiscussionGroup(~490subscribers)andontheAAVSOwebsite(417reads).We sent ane-mail to thosewhowerecurrentAAVSOmembersorwhohadmadeanobservationwithinthelastfiveyears(~2,400e-mails).Weidentifiedeightpeoplewhomet thatcriteriabutwhodidnothavee-mailaddressesonrecord.Forthem,weprintedacopyofthesurveyandsentitusingpostalmail.Atotalof691validresponseswerereceivedtotheonlinesurveyandfouroftheprintedsurveyswerereturned. We tabulated the results into an Excel spreadsheet. For the open-endeditems,wecoded them intoa setofcategories that included99%ormoreofthe responses.Whenaparticular itemresponsecould fit intomore thanonecategory,thefirstcategorymentionedintheresponsewasused.Thiswasbasedontheassumptionthatthefirstitemmentionedbytherespondentwasthemostimportant to them. The ranking items were scored on an ordinal scale (thehighest ranking item is assigned a “1” and the rest are ranked accordingly).Wetreateditemsthatwerenotansweredasmissingdata.WemadeourfinalanalysiswiththePASWStatistics18software(formerlySPSSStatistics,nowIBMSPSSStatistics).

3.1.Definitions For the purposes of this survey, we refer to respondents as anyone whoansweredatleastoneitemofthesurvey.Also,wecombinedCharge-CoupledDevice (CCD), Photoelectric Photometry (PEP), and Digital Single-LensReflex(DSLR)technologiesbeneaththeumbrellatermofdigital technologies.Visual observationsincludeanyobservationmadewiththeeye,whichincludesnaked eye, binoculars, and telescopic observations made with an eyepiece.Membership statuswasassignedbasedonAAVSOheadquartersrecordsasofJanuary2012. The profession categories included items were taken from the U.S.Department of Labor categories used in the 2011 U.S. Census (U.S. Dept.ofLabor2011).Thecategoriesofobjectswere taken from thehighest levelcategoriesusedbytheVariableStarIndex(VSX)(AAVSO2011),whicharebasedoncategoriesoriginallydevelopedbytheGeneral Catalogue of Variable Stars(GCVS;Kholopovet al.1985).


4. Results

4.1.Age Themeanageofsurveyrespondentsis53(N=671;Figure1).Thereisnosignificantdifferencebetweenthemeanagesofmenandwomen,norofthemeanagesbetweendigitalandvisualobservers.The1994surveyreportsfrequenciesinstead of means. The mean frequency category was “41–50” (N=420).CitizenSkymembers report ameanageof41 (N=1,385).Sky & Telescopemagazine reports a mean subscriber age of 51 (New Track Media 2010). TheAAVSOmaintainsanarchiveofmembershipapplicationsdatingbackto1911.Almostallapplicationsincludeeithertheapplicant’sageorbirthdate.Werandomlyselected615applicationsandplottedtheirageasofthemomenttheyjoinedtheorganization(Figure2).Therearesomegapsinthedatafromincompleterecords(namely1911–1918,1922–1928,and2004–2008).Overtheentire100-yearperiod, theaverageageofanAAVSOmembershipapplicantwas 37 years old. During 1911–1921, the average new member age was 40years.Newmemberagedroppedto28yearsduringtheyears1967–1977andwas51yearsfortheyears2001–2011. The average age of observers does not vary much among the variousobservingtechniquesincludedinthesurvey(Figure3).TheageofPEPobserversistheonlycategorythatstandsout.Wefoundslightlymorevariationbetweenthe average ages of those engaged in non-observing activities (Figure4). Inparticular, the more “high-tech” activities of programming and data miningtendtohaveslightlyyoungerparticipants.

Figure1.Histogramofageofsurveyrespondents.Themeanageis53.31;StandardDeviation=13.384;N=671.

Figure2.Ageofnewmemberapplicants.


4.2Yearsactive “Years active” is a variable computed from subtracting the first year arespondent reported to be active in theAAVSO from 2011. It represents anapproximation of how long survey respondents have been active in theorganization.Themeanis14.3years(SD=15,N=598).Thereseemstobeadropoffatyears2and5,afterwhichdropoutratesflatten(Figure5).MembersoftheAAVSOtendtobeinvolvedintheorganizationforsixyearslongerthannon-members,adifferencewhich is statisticallysignificant,F (1,503)=22.0,p<.001.

Figure3.Averageageofsurveyparticipantsasafunctionofobservingtechnique.

Figure4.Averageageofsurveyparticipantsasafunctionofnon-observingactivity.

The1994surveyincludedfrequenciesofthenumberofyearsrespondentshaveobservedvariable stars (notea slightdifferencebetween theirquestionabout “observing” and our question about “being active”) separated into 5-yearbins(Figure6),sowewereunabletocomputeamean.Theonlymajordifferencebetweenthe1994and2011distributionsisadropoffafter30yearsthatappearsinthe1994survey,butnotinthe2011survey.

Figure5.Numberofyearsactiveofall2011surveyrespondents.

Figure6.Numberofyearsactiveofobserversonly,from1994survey.


In order to get more detail from the period around the 1980 survey, werandomlyselected26observersfromtheAAVSOInternationalDatabase(AID)whohadsubmittedobservations in1977(chosen tomatch thesame intervalbetween1994and2011)andpulledtheiroriginalmembershipapplicationtosetadatefortheirjoiningoftheorganization.Wecomputedthedifferencebetweenthatdateand1977as theirAAVSOAge(Figure7).Themeanagewas10.8years.ThemeanAAVSOAgeofmembersinthe2011surveywas16.8years.Thedistributionsaresimilar,butnotthesame.Thedrop-offsseeninthe2011surveyatyears2and5occurinthe1977data,butayearortwolater.Overall,thetrendsareverysimilar.

4.3Membershipstatus Membershipstatuswasdeterminedbylookingupanobservercodeore-mailaddress(whenprovided)intheAAVSOmembershipdatabaseonJanuary18, 2012. At that time, 54% of respondents were official members of theAAVSO. In the 1994 survey, 85% of the respondents were members of theorganization(N=417),accordingtoself-reporteddata.Inthe1994survey,wereceivedobservationsfrom660observers.In2011,wereceivedobservationsfrom1,050observers.Theobserver/membership ratiodifferencemay reflectmore thegrowthofobservers rather than the lossofmembers.TheAAVSOdoesnotkeeparecordofmembershiptotalsperyear. Wealsolookedforarelationshipbetweenmembershipstatusandwhethertherespondentreportstobeanactiveobserverornot.Wefoundnosignificantrelationship. However, for those who were active, there was a significantrelationship between the techniques they used and their membership status,F(390,8)=2.21,p=.03(Figure8).Themostinterestingresultisthat60%oftelescopicCCDobservers(N=143)aremembersand43%oftelescopicvisualobservers(N=138)aremembers.Thisdifferenceisstatisticallysignificant,F(315,1)=7.36,p<.01.

Figure7.Yearsofactivityofmembersandobserversactivein1977(N=26).

Figure8.Membershipratesforparticpantsasafunctionofvariousobservingtechniques(*=categorieswithfewerthan15memberrespondents).


4.4.Gender 92% of respondents identified as male (N=634) and 8% identified asfemale(N=44).Themeanageforwomenis49,whilethemeanageformenis53,howeverthedifferenceisnotstatisticallysignificant(p=.06).Thelowsampleoffemalesmakesitdifficulttolookforrelationshipsbetweengenderandothervariablesinthesurvey.Inthe1994survey,thedistributionwas94%maleand6%female,veryclosetothecurrentratio.Sky & Telescopereportsagenderratioof95%maleand5%femaleintheir2010advertisingratecard(NewTrackMedia2010).TheCitizenSkygenderdistribution is78%male,19%female,and3%unreported(N=1,385).

4.5Country 108differentcountrieswererepresentedinoursurveyresults.About49%ofrespondentswerefromtheUnitedStates.Therestwerewidelydistributedamong theother107 countries (Figure9). 28 countrieswere representedbymembersand46countrieswererepresentedbyactiveobservers.

4.6Formaleducation Almost a quarter of the respondents claimed to have a terminal degree(Ph.D.,M.D.,J.D.,andsoon)intheirfield(Figure10).About76%reportaBachelor’sdegreeorhigher,whichisclosetoSky & Telescope’srateof77%(NewTrackMedia2010).

Figure9.Topcountriesrepresentedbymembership,excludingtheUnitedStates.

Figure10.Reportedformaleducationofrespondents(N=656).

There is a significant relationship betweenprofessionandobservationtype,F(9,438)=3.44,p<.01. Most of that significance is due to theincreasededucationlevelsofthespectroscopicobservers (N=32) and decreased educationlevelsreportedbythesunspotobservers(N=22)(Figure11).

Figure11.Averageformaleducationoftheusersofvariousobservationtechniques.EducationlevelreflectsthecategoriesinFigure10inascendingorder.


Therearealsosomecorrelationsbetweeneducationandthetypeofobjectstherespondentsfavoredtoobserve(Table1).Specifically, thosewithlessofaformaleducationtendtobemoreinterestedinnovae(N=421,q=.139,p<.001)andtheSun(N=404,q=.121,p<.05).Also,thosewithmoreofaformaleducationtendtobemoreinterestedinrotatingvariables(N=354,q=–.107,p< .05).Allof these relationshipsareconsideredsmallby traditionalsocialsciencestandards(Cohen’sGuidelines).

Table1.Intercorrelationsbetweenformaleducationandinterestinobjects. CV EB Extra- Novae Non- Pulsating Rotating Sun YSO galactic Stellar

Formal Education

–.044 –.055 .074 .139* .022 –.055 –.107** .121** –.049*p<.01,**p<.05.

4.7.Profession Thereporteddistributionofprofessions(N=615)canbebrokendownintotwocategoriesofhighandlow(Figure12).Themostcommonprofessionswereinscience,computerscience,engineering,andeducation.Thosefourcategoriesaccountforabout57%oftherespondents.Therestoftheothercategorieswereroughlyeven,withmanagementandhealthcare leading thegroup.BuildingandGroundsCleaninghadthefewestresponses.

Figure 12. Distribution of professions according to U.S. Department of Labor categories: a.Transportationandmaterial;b.Salesandrelated;c.Protectiveservice;d.Production;e.Personalcare and service; f. Office and administrative support; g. Mathematical and computer; h.Management;i.Life,physical,andsocialscience;j.Legal;k.Installation,maintenanceandrepair;l.Healthcarepractitionersandtechnical;m.Foodpreparationandserving;n.Financial;o.Farming,fishing,andforestry;p.Engineering,architectureandsurveyors;q.Education,training,andlibrary;r.Constructionandextraction;s.Communityandsocialservices;t.Buildingandgroundscleaning;u.Arts,design,entertainment.

The 1994 survey had a similar question, but with fewer professioncategories to choose from.Table2 is a comparisonof results from the twosurveysincategoriesthataresimilar.Ingeneral,thereisnotmuchdifferencethatcannotbeexplainedbydifferencesinthedefinition/labelingofcategoriesbetweenthesurveys.


4.8.Astronomyexperience Almosthalf(49%)oftherespondentsclassifiedthemselvesashavinganadvancedlevelofexperienceinastronomy(Figure13).Thereisasignificantbutlowpositivecorrelationbetweenastronomyexperienceandthevariablewecall“YearsActive”(r=.208,p<.001).Thereisalsoasignificantcorrelationbetweenageandastronomyexperience,r=.087,p<.05,butitisweakerthantherelationshipwithYearsActive.Infact,whencontrollingforYearsActivethroughanANCOVA,age isno longerasignificantpredictorofexperience,F(67,587)=1.11,p=.125.

Table2.Comparisonof1994and2011reportedprofessions(selected). 1994 2011 1994 2011 Category Category Response (%) Response (%)

Scientific/Technical Life,Physical, andSocialScience 41 17(31*) ProfessionalAstronomer (none) 12 13**

Educator Education,Training, andLibrary 18 14 ComputerSpecialist Mathematicaland ComputerScientists 9 11 BusinessManagement Management 5 6 Sales/Marketing Sales,andRelated 1 1*When combining this category with “Engineering, Architecture, and Surveyors.”**Taken from astronomy experience responses (see text).

Figure 13.Astronomy experience levels of ofrespondents(N=658).

Figure14.SourcesofmotivationtoparticipateintheAAVSO(N=351).

4.9.Motivation Supporting science and research (“citizen science”) is the most popularreasonrespondentsgaveforbeingactiveintheAAVSO.Aclosesecondisaninterestinvariablestars(Figure14).Around9%ofrespondentsareactiveintheAAVSOduetoprofessionalorgraduatestudentresearch.


4.10.Barrierstoactivity Toinvestigatebarrierstoactivityweaskedanopen-endedquestionwordedas:“IfyouarenotcurrentlyactiveintheAAVSO,whatisthemainreason?”Almost all respondents who previously reported to be inactive (N=192)providedananswertothisitem.Notethevaguedefinitionof“active”inthequestion.Wepurposelyallowedtherespondenttodefineactivityintheirownwaysoas to include thosewhowouldotherwisebeactive innon-observingcontexts.Time(43%)wasbyfar themainreportedreasonrespondentswereinactive (Figure15).Other astronomy interestswas second (14%), followedbyalackofequipment/poorlocation(12%).Muchofpoorlocationcommentswerereportedasproblemswithlightpollution.

Figure 15. Major reasons to be inactive /barrierstoactivity(N=192).

4.11.Referralsources People learn about the AAVSO from a variety of sources (Figure 16).Wordofmouth(25%)ismostcommon,followedcloselybyotherastronomycluborconferences(19%),Sky & Telescopemagazine(19%),andtheInternet(18%).The1994surveyalsoincludedaquestionaboutreferralsources.Itwasstatedas:“HowdidyoufirsthearabouttheAAVSO?”andhad427responses(Figure17).

Figure16.Referralsourcesinthe2011survey. Figure17.Referralsourcesinthe1994survey.

The biggest difference between the 1994 and 2011 surveys is the 35%to19%dropinreferralshareattributedtoSky & Telescopemagazine.Sky & Telescopehaslongbeenanimportantsourceofbrandingfortheorganization,butithasdroppedinsignificance.ThisislikelyduetotheabilityoftheAAVSOtoreachamateurastronomersdirectlythroughtheInternet.Ifyouaddupthe


referralshareofthe“Internet”and“Sky & Telescope”inthissurveyitreaches37%, which is very close to the 35% share in the 1994 survey (and in linewithgeneralsocietaltrends).Clubandbookscontinuetohavesimilarsharesbetweenthe1994and2011surveys,at18%–19%and12%–9%respectively.Interestingly,non-Sky & Telescopemagazinesalsohaveasimilarsharebetweensurveys,at7%–8%. Inthe2011survey,wecodedtalksintothe“Wordofmouth”category.Ifyoucombinethe“Other(talks…)”and“Friends”categoriesinthe1994survey,thentheytoohaveasimilarsharewiththe2011“Wordofmouth”categoryat28%–25%. The1980surveyincludedareferralquestionaswell.Itwasstatedas:“SourceofinformationabouttheAAVSO?”.Waagen(1980)dividedtheresponsesinto5categories(Figure18).Ingeneral,theyareconsistentwiththeothersurveys.Themajordifferencebeingthelargesharebooksheldin1980(21%)asopposedto 1994 (12%) and 2011 (9%). Club referrals also dropped between 1980(23%)and1994(18%)whileremainingconsistentfrom1994to2011(19%).

Figure18.Referralsourcesinthe1980survey.

4.12.Observationactivity Weaskedrespondentstodeclarewhethertheyconsiderthemselvesactiveobserversornot.Wedidnotdefinetheterm“active.”Almosttwo-thirds(63%)oftherespondentsreporttobeactive(Figure19).Similarly,the1994surveyaskedobserverstoclassifythemselvesintovariouscategoriesofactivity.78%choseacategorydenotingactivityand22%choseacategorydenotinginactivity.Thus,thepercentageofinactiveobservershasincreasedsincethelastsurvey.Inthe1980survey,93%reportedtobe“anobserver.”

Figure 19.Active and inactive observer rates(N=691).


Wewereinterestedtoseewhethertheincreaseininactiveobserverswasrelated to any of the non-observing activities in the AAVSO. An ANOVA(ANalysisOfVariance)foundasignificantdifferencebetweentheactiveandinactivegroupsbasedonwhethertheyarealsoactiveinanon-observingactivity,F(10,644)=1.9,p<0.05.Figure20isaplotofthemeanobservationactivityvalue(lowernumbermeansmoreactive)groupedbynon-observingactivitieslistedinthissurvey.Itisofnosurprisethatthemanyactiveobserversarethoseinvolvedinthechartprocess,sincechartshaveadirectimpactonobserving.Itisalsointerestingthattheleastactivearethoseinvolvedinfinancialaspectsoftheorganization.Programmerstendtobeactiveobserversaswell.Beyondthat,therestofthecategoriesareroughlyeven.

Figure 20. Activity rates of respondents whoparticipateinnon-observingactivities.

4.13.Faintestobservation We asked observers to report the magnitude of the faintest observationthey“typically”observe(Figure21).Wethenaskedwhetherthatobservationwasmadevisuallyorwith“CCD/DSLR/PEP/OtherDigitalsystem.”Thiswasmore useful than asking if a person was a “visual or CCD” observer sincemanyusebothtechniques.Instead,thisquestiontellsuswhichtechniquetheyused to get their faintest observation, which will almost always be “CCD”

Figure 21. Faintest observations (magnitude)“typically” recorded by respondents. Mean =13.75;StandardDeviation=3.45;N=365.


for CCD/combined observers and “visual” for visual-only observers (for amoredetaileddiscussionofobservation type see theobservation technologysection). The goal of these questions was to establish magnitude ranges forvisualorCCDcampaigns.Observersweredividedroughlyinhalfbetweenthetwo(Figure22).Themeanfaintestvisualobservationwas12.02andthemeanfaintestCCDobservationwas13.75.Thevisualdistributiondropsoffsharplyaroundmagnitude15–16whiletheCCDdistributionfadesmoregraduallyuntilaroundmagnitude20(Figure23).

Figure 22. How the faintest observation inFigure21ismeasured.

Figure 23. Distribution of the faintest “typical” observation made through CCD or visualmeasurements.

4.14.CCDorigins Wewereinterestedinhowoftenvisualobservingisusedasasteppingstonetodigitalobserving.Weaskeddigitalobservers:“IfyouareaCCD/DSLR/PEPobserver,didyoubeginasavisualobserverwhomigratedtoCCD/DSLR/PEPordidyoubeginasaCCD/DSLR/PEPobserver?”Abouthalfoftherespondentsreportbeginningasavisualobserver(Figure24). ThisresultissomewhatbiasedbecauseitincludesthegenerationofAAVSOobserverswhobeganwhenvisualwastheonlyoption.Whenwelookedattheanswersofonlythosewhobecameactivewithinthelast10years(usingthe“YearsActive”variable,N=119)wefound67%beganwithCCDandonly33%beganasvisualobservers.Ifwetightenthewindowfurtherandonlylookatthelast5years(N=79),wedon’tfindmuchadditionaldifferenceasabout28%ofCCDobserversbeganasvisualobservers(Figure25).Currently,visualobservingisaneffectiveentrypointforroughlyaquarterofnewAAVSOCCDobservers.


4.15.Observationtechnology We provided respondents with a list of observation technologies andasked them to select which types they “actively use” (N=460, Figure 26).Interestingly,40%ofthosewhoreportedtobetelescopicCCDobserversarealsoactiveasvisualtelescopic(N=54)ornakedeye(N=34)observers.Also,thenumberofthosewhoreportedtobeobserversutilizingspectra(N=32)wassurprising,sincetheorganizationhasnoformalgrouporsectiontostandardizethis activity. Lastly, more than half of all observers use multiple observingtechniques(Figure27).

Figure24.Background(origins)ofactiveCCDobservers.

Figure25.Backround(origins)ofactiveCCDobserversforthelast10years(left),andlast5years(right).

Figure26.Numberofactiveobserversusingvariousobservationtechnologies.

Figure27.Numberofdifferentobservingtechnologiesusedbyactiveobservers.


4.16.Non-observingactivities Byfar,themostpopularnon-observingactivitiesinvolvedpublicoutreach(Figure 28). Specifically, giving talks and writing about theAAVSO. Priorsurveysdidnotincludeitemstoaddressparticipationintheseareas.Wefoundno significant relationships between non-observing activity and observationtechnologyorwithmembershipstatus.

Figure28.Numberofrespondentsparticipatinginvariousnon-observationactivities.

4.17.Objectinterest Whenaskedtorankobjectsbyinterest,wefindaclusteringofobjectsintotwocategories:highlyranked(Pulsating,CV,EB,Novae,Extragalactic)andlesserranked(YSO,Sun,Rotating,NonStellar)(Figure29).Respondentswereonlyallowedtoprovideoneobjectforeachranking.However,theywerenotrequiredtorankeveryobject.Somerespondentsonlyrankedtheobjectstheyweremost interested in (example: theyonly ranked the top5). Inaseparatetabulation,weassignedarankingof9(thelowestrankpossible)tothoseobjectsthathadmissingdata,withthejustificationthattherespondenthadnointerestinthatobject.Theonlymajordifferenceisthatthedropoffbetweenthehighlyrankedgroupandthelesserrankedgroupincreases.33typesofobjectswereincludedinthe“Other”category(Table3).Manyofthesetypesofobjectscouldbeincludedinexistingsurveycategories.

Figure29.Popularityofvariousvariablestarobjecttypes.

4.18.Meetingattendance Themeannumberofmeetingsattendedbyarespondentwas1.5(N=584;Figure 30). However, that number is significantly skewed because of fourrespondentsofreportedbetween20–60meetings.Theoverallsurveymedianvalue is 0, meaning that the vast majority of respondents had not attendedanAAVSO meeting before. By excluding those who have not attended any


Exoplanets 17Asteroids 9RCB’s 6Be,ShellorGCASstars 4Symbioticvariables 3Carbon 3SpottedorRSCVn 2GRB’s 2HMXB’s 2Globularvariables 2Non-specific(general) 2Brightvariables 2Recurrentnovae 2SR’s 2Irregulars 1Doubleormultiple 1Infra-redstars 1

Table3.Objectsincludedinthe“Other”field.

HAD’s 1Supernovae 1CoolSupergiants 1Central-planetarynebulae 1Thermalpulsecandidates 1AGB’s 1Emissionlinestars 1Mira’s 1NSV’s 1ISM 1RRLyr 1DelSct 1SXPhe 1Neutronstars 1Whitedwarfs 1Interestingstellarspectra 1

“Other” Objects Number “Other” Objects Number

meetings, and the two persons who reported 40 and 60 meetings, then theaveragemeetingattendanceis4.2.Thisnumberreflectsthenumberofmeetingssomeonewouldtypicallyattendiftheyhaveattendedatleastone.

Figure30.NumberofAAVSOmeetingsattendedbyrespondents.

We looked for relationships between meeting attendance and the typeof observations people make and the types of non-observing activities theyparticipatein(Figure31).Fortypesofobservations,wefoundnosignificantrelationships.Fornon-observingactivities,wedidfindasignificantrelationship,F(573,10)=15.4,p<.001.However,mostofthatstatisticalrelationshipisduetothosewhoselected“HQVolunteer.”WebelievethistobeaperplexingvariablebecausethosewhovolunteeratHeadquarterstendtolivenearHeadquarters,thusattendtheannualmeetingquiteoften.InFigure31,wezoomedinontheothercategories.Themaindifferencebetweentheactivitiesthatinvolvemoreinvestmentofinitiative(writing,programming,mentoring,andsoon)thaninactivitiesthataremoreprocedural-based.Finally,membersaremorelikelyto


attendmeetings(mean=2.5meetings)thannonmembers(mean=0.3meetings).Thisdifferenceisstatisticallysignificant,F(1,483)=31.1,p<.001.

4.19.Paperauthorship Alittleovera thirdof therespondentsreported tobeeitheranauthororcoauthorofapaperinanastronomicaljournal(36%).Noneofthepriorsurveysincludedpaperauthorship.

5. Discussion

Overall,the2011surveydepictsthoseparticipatinginAAVSOactivitiesassimilartothosedescribedinthe1980and1994surveys.Theyarelargelymale,older,highlyeducated,andtendtoworkinscientificortechnicalfields.MostareactiveobserversandhavebeenaffiliatedwiththeAAVSOfordecades. Thesurveyalsosuggestsareasofsignificantchangeovertime.First, theaverageageofnewmembershasbeenincreasing.Thisbeganinthe1980sandhascontinued.Originally,theincreaseinagewasmostlyattributedtothelossofyoungermembers.Morerecentlyitcanalsobeattributedtoanincreaseinoldermembers.Theoverallsizeoftheorganization’smembershiphasnotdiminishedoverthissametimeperiod.This“greyingofastronomy”isanissuethataffectsamateurastronomyasawhole.TheaverageageofaSky & Telescopesubscriberwas39in1979,48in1998,and51in2010(Beatty2000;NewTrackMedia2010).Ananalysisof theaverageageofprofessionalAmericanastronomersfoundanincreaseofaroundhalfayearperyearinthemid1980s(Thronsonand Lindstedt 1986). However, the AAVSO Citizen Sky project has beenmoresuccessful inrecruitingyoungerobservers.It reportsameanageof41(N=1,385).Forcomparison,themedianageintheUnitedStatesasofthe2010censuswas37.Thecausebehind this trend iscomplicatedandmultifaceted.Oneissuecouldbetheimpactofthecoldwarspaceraceoninterestinscienceinthe1950sand1960s.Anothercouldbetheincreasingentertainmentoptionsforadecreasingamountofpersonaltime.Amateurastronomyhasalsobecomealargelyhigh-techendeavorrequiringsignificantinitialfinancialinvestment.

Figure31.Numberofmeetingsattendedbyparticipantsofvariousnon-observingactivities.


Amoredetailedinvestigationoftheagequestionisplannedforafuturestudy.Another major difference between surveys is where and how respondentsheardabouttheAAVSO.TheInternetisreplacingmanyofthereferralswhichpreviouslymayhavecomethroughSky & Telescopemagazine.Itisinterestingthat referrals from books and non-Sky & Telescope magazines have notchanged much between the 1994 and 2011 surveys.This suggests the issuemaybe specific toSky & Telescope,perhapsdue to itspreviouslydominantpositionasamajorreferringsourceand/orbecauseSky & Telescope ismorecloselyassociatedwithadvancedamateurastronomersthancasualreaders.ItispossiblethattheInternetisimpactingnewsstandsales(casualreaders)lessthancirculationsales(moreadvancedreaders). In terms of observing methodology, active observers are pretty evenlydividedbetweendigitalandvisualobserving.Sincethe1990s,therehasbeendiscussionaboutcompetitionbetween the two typesofobserving.However,wefoundthat40%oftelescopicCCDobserversarealsovisualobservers.Also,abouthalfofallCCDobserversandaquarterofnewCCDobserversbeganasvisualobservers.Thissuggeststhelinedistinguishingthesetwogroupsismuchfuzzierthanhasbeenadvertised. Therearesomesurprisingresultsaswell.First,AAVSOactivityisrelatedtoagreaterincreaseinself-efficacyinastronomythanonewouldfindthroughincreasedastronomyexperiencealone (asmeasured throughage).That is, itispossiblethatthedemandsofvariablestarresearchhaveagreaterimpactonhowoneviewstheirknowledgeofastronomythantheactivityofthetypicalamateurastronomer.Thiscouldhintatgreaterlearningtakingplaceinactivecitizenscienceprojectswhencomparedtotypicalamateurastronomyprojects.Afuturestudyisplannedtoinvestigatethisresult.AsecondsurprisewasthenumberofrespondentswhoreporttobeactiveintheAAVSO,butalsoreporttobeinactiveobservers.ThisreflectstheincreasedscopeoftheAAVSOoverthepasttwodecades.Whenthepasttwosurveyswereconducted,non-observingactivitieswerenotevenconsideredunlesstheywereinsupportofobserving.Now,manyparticipantsoftheAAVSOarededicatedtoimportantprojectssuchasprogramming,analysisofdata,publicoutreach,andsoon.ObservingisstilltheheartoftheAAVSO,with60%ofthosewhoreportparticipationinatleastonenon-observingactivityalsoreporttobeactiveobservers.Anothersurprisewasthehighlevelofeducationreported.Overhalfofparticipantsreportagraduatedegree,with24%reportingaterminaldegreeintheirfield(Ph.D.,M.D.,J.D.,andsoon).Also,13%identifyasprofessionalastronomers(N=86).Oneofthemost interestingsurprises is thenumberofcountriesrepresentedbyAAVSOmembership(108).Thismayreflectthesignificantworkthatvolunteershaveputintotranslatingourtrainingmaterialsintootherlanguages,butitislikelyabiggerreflectionoftheuniversalappealofvariablestars.Therearesimplysomanytypesofstarsandsomanyopenquestions,thatalmostanyonecanfindaproject or object of interest.Finally, thenumberof respondentswhohave


authoredorcoauthoredapaper inascientific journalwasquitehigh (36%).ThisisoneofthemajordistinguishingcharacteristicsbetweentheAAVSOandothercitizenscienceorganizations,whotendtofocusonusingparticipantstocontributedataforprofessionalstoanalyzeandpublish. Raddick,et al.(2010)identified12categoriesofmotivationfromGalaxyZooparticipantsthroughanalysisofinterviewsandonlineforumposts.Aswithoursurvey,theircategorieswerereducedfromopen-endeddiscussion(intheircase, interviews were also included). In areas where our categories overlapwiththeirs,wefindsimilaritiesandsomesignificantdifferencesinmotivationrates.Theyreportonly1%oftheirresponsesaremotivatedby“science”while“scienceandresearch”wasthemotivationof35%ofourrespondents,whichwasourhighestcategoryofmotivation.TheGalaxyZooprimarymotivationcategorywas“astronomy”at39%.Ifthatreferstointerestinastronomy,thenitisanalogoustoour“interestinvariablestars”categorythatwascitedby32%ofourrespondents.Ourtwogroupsreportthesamelevelofmotivationintermsofcontributingdatatoagreatercause.13%oftheGalaxyZooparticipantsciteadesireto“contribute”asamotivationoftheirparticipationwhileanidentical13%ofourrespondentsciteadesireto“sharedata.” Thisstudyhasanumberoflimitations.First,itisastudyofactiveorrecentlyactiveparticipantsof theAAVSO.Somedata, suchas the ranked interest intypesofobjects,willbeskewedtowardscurrentoperations(peopleinterestedinexoplanets,forexample,mayhavedroppedoutoftheorganization).Sothisdatashouldnotbeusedasaguideforthefuture,butonlyasasnapshotofthepresent.Second,thecodingoftheopen-endeditemswaslimitedtoonecodeperitem.Soitmayoversimplifytheresultsofthoseitems.Thereisastrikingsimilaritybetweenourresultsandpastsurveysontheseitems,whichsuggestsstrongvalidity.Finally,thisisselfreporteddata.Thusitincludesbiasescausedbyhumannatureanddifferentdefinitionsofterminology.Forexample,somerespondentsreporttobeprofessionalastronomersyetalsoreporttonothaveaPh.D.Wearenotstatingtheyarenotprofessionals,justthatrespondentswillhavedifferencedefinitionsof the term“professional.”Tosome, it requiresa“Ph.D.” while for others it denotes publishing in journals while still othersapplythetermtoanyonecontributingscientificallytoastronomicalresearchatanylevel.

6. Conclusion

ThisisasummaryreportoftheAAVSO2011DemographicSurvey,whichincludedcurrentandrecentAAVSOparticipants.Comparedwithpastsurveysofthistype,itshowsanorganizationthatislargelysimilarindemographics.Respondents were active in a wide variety of observing and non-observingactivitiesandareinterestedinawidevarietyofobjects.TheAAVSOreflectsa “big tent” mentality, with room for everyone interested in variable stars.


There are signs in thedata of some challenges, such as a population that isgrowing older and the presence of a very significant gender gap. However,thesearenotlimitedtotheAAVSOalone.Asadescriptiveanalysis,wemakeno predictions for the future. However, the results can be used, along withother surveysandanalysis, to identify futurepathsandopportunities for theorganization.

References

AAVSO 1976, AAVSO Archives, JAM Adm., Box 3 and 4, Survey ofMembership,AAVSO,Cambridge,MA.

AAVSO2011,VariableStarIndex(http://vsx.aavso.org).Beatty,K.2000,Sky & Telescope,100,3.Hazen,M.L.1995,J. Amer. Assoc. Var. Star Obs.,23,143.Kholopov,P.N.,et al.1985,General Catalogue of Variable Stars,4thed.,Moscow.Lowder,W.M.1994,AAVSOArchives,JAMOrg.,Box3B,FuturesStudy(2),

AAVSO,Cambridge,MA.NewTrackMedia2010,Reader Demographics Rate Card,51,1.Price,C.A.,andLee,H.-S.J. Assoc. Res. Sci. Teach.,inpress.Raddick,M.J.,Bracey,G.,Gay,P.L.,Lintott,C.J.,Murray,P.,Schawinski,K.,

Szalay,A.S.,andVandenberg,J.2010,Astron. Education Rev.,9,1.Thronson,H.A.,andLindstedt,S.L.1986,Publ. Astron. Soc. Pacific,98,941.U.S.DepartmentofLabor,BureauofLaborStatistics.2011(November1),List

of SOC Occupations (retreived from http://www.bls.gov/oes/current/oes-stru.htm).

Waagen,E.O.1980,J. Amer. Assoc. Var. Star Obs.,9,92.Williams,T.R.,andSaladyga,M.2011,Advancing Variable Star Astronomy:



12.Whatdoyouconsiderwasthe*first*yearyouwereactiveintheAAVSO?(ex:1975,1990,etc.)__________________________________________________________________________13.WhatwasthemainreasonyoubecameactiveintheAAVSOatthattime?__________________________________________________________________________14.Howdidyouhear/learnabouttheAAVSO?______________________________________15.IfyouareactiveintheAAVSOrightnow,whatisyourcurrentmaininterest?___________16.IfyouarenotcurrentlyactiveintheAAVSO,whatisthemainreason?________________17.Areyouanactivevariablestarobserver?(circleone) Yes No18.Ofall theobserving techniquesyoumayuse,what is themagnitudeof thefaintestpositivevariablestarobservationthatyouroutinelymake(donotcountfainterthans)?_____________19.Howdoyoumakethosefaintobservations?(checkone) ______Visual ______CCD/DSLR/PEP/OtherDigitalsystem

• HighSchoolorequivalent • Associatesdegree(2-year)orequivalent • Bachelorsdegree(4-year)orequivalent

• Mastersdegreeorequivalent • M.D./J.D/Ph.Dorequivalent

Appendix A

This is the printed version of the AAVSO 2011 Demographic survey. All items are worded exactly as they appeared online, except for the state and country items, which included drop down lists. In a few areas, screen shots of the online form were used in the printed survey as well.

AAVSO 2011 Demographic survey

1.Whatisyourname?__________________________________________________2.Ifyouhaveanobservercode,whatisit?__________________________________3.Doyouwantacopyofthesummarizedresultsofthissurvey? Ifso,enteryouremailaddresshere:____________________________________4.Whatisyourgender?_________________________________________________5.Whatisyourage?____________________________________________________6.Zipcodeorpostalcode:_______________________________________________7.Inwhatcountrydoyoulive?___________________________________________8.Inwhichstateorterritoryisyourprimaryresidence?________________________9.Whatisyourhighestlevelofcompletedformaleducation?(circleone)

10.Whatisyourprimaryfieldofprofession?(circleone) (thefollowinglistisfromtheU.S.DepartmentofLabor) • Arts,Design,Entertainment, SportsandMedia • BuildingandGroundsCleaning andMaintenance • CommunityandSocialServices • ConstructionandExtraction • Education,TrainingandLibrary • Engineering,ArchitectureandSurveyors • Farming,FishingandForestry • Financial • FoodPreparationandServingRelated • HealthCarePractitionersandTechnical

• Installation,MaintenanceandRepair • Legal • Life,PhysicalandSocialScience • Management • MathematicalandComputerScientists • OfficeandAdministrativeSupport • PersonalCareandService • Production • ProtectiveService • SalesandRelated • TransportationandMateiral-Moving • Other(pleasespecify)

• Novicewithverybasicastronomyexperience • Intermediatelevel

11.Whatisyourlevelofastronomyexperience?(circleone) • Advancedlevelbutnotinaprofessionalcapacity • Professionalastronomer,astrophysicist,etc.


24.HowmanyAAVSOmeetingshaveyouattended?___________________________________25.If1ormore,inwhatyeardidyoulastattendanAAVSOmeeting?______________________26.Haveyoubeenanauthororcoauthorofapapersubmittedtoanastronomicaljournal(JAAVSOincluded—checkone)?_____Yes_____No27.Doyouhaveanygeneralcommentsyou’dliketoshare?

21.Selectthefollowingobservingtechniquesthatyouactivelyuse(circleasmanythatapply): • Nakedeye • Binoculars • DSLR

• Telescopevisual • TelescopeCCD • TelescopePEP

• Spectroscopy • Sunspotcounting • SIDmonitoring

• AAVSONetorother roboticsystems • Other(pleasespecify):

22.Selectthefollowingnonobservingactivitiesinwhichyouarecurrentlyactive (circleasmanythatapply): • AAVSOnethardwareorsoftwaresupport • Activelycontributingtoacommittee, divisionorsection • Chart/SequenceDevelopment • Dataarchiving • Datamining • Financial support (beyondmembership fees)

• Mentoring • Programming • PublicSpeakingandTeaching • HaveservedonCouncilatanypointintime • VolunteeringatHQ • Writing • Other(pleasespecify):

23.Pleaserankthetypesofobjectsyouaremostinterestedin(fillinthecircle).Pleasechooseonlyoneitemforeachrank.Forexample,onlyoneobjectshouldbeassigneda“1”,onlyoneobjectshouldbeassigneda“2”,etc.

20.IfyouareaCCD/DSLR/PEPobserver,didyoubeginasavisualobserverwhomigratedtoCCD/DSLR/PEPordidyoubeginasaCCD/DSLR/PEPobserver?(checkone) IbeganmakingvariablestarobservationsasavisualobserverwhomigratedtoCCD/DSLR/PEP/etc. IbeganmakingvariablestarobservationsasaCCD/DSLR/PEP/etc.observer.

1=MostInterested 5=Neutral 9=LeastInterested 1 2 3 4 5 6 7 8 9 Rotational Variables ○ ○ ○ ○ ○ ○ ○ ○ ○ Cataclysmic Variables (Dwarf Novae, Novalike, etc.) ○ ○ ○ ○ ○ ○ ○ ○ ○ Non-stellar Objects ○ ○ ○ ○ ○ ○ ○ ○ ○ Young Stellar Objects ○ ○ ○ ○ ○ ○ ○ ○ ○ Eclipsing Binaries ○ ○ ○ ○ ○ ○ ○ ○ ○ Novae ○ ○ ○ ○ ○ ○ ○ ○ ○ Pulsating Variables (Cepheids, Miras, RR Lyr, etc.) ○ ○ ○ ○ ○ ○ ○ ○ ○ Extragalactic Objects (supernovae, blazars, etc.) ○ ○ ○ ○ ○ ○ ○ ○ ○ The Sun ○ ○ ○ ○ ○ ○ ○ ○ ○ Other(pleasespecify)

Landolt, JAAVSO Volume 40, 20121032

The Citation of Manuscripts Which Have Appeared in JAAVSO

Arlo U. LandoltDepartment of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803; [email protected]

Received May 3, 2012; revised May 14, 2012; accepted May 15, 2012

Abstract A study is presented of the use by the astronomical communityof themanuscriptspublished inThe Journal of the American Association of Variable Star Observers(JAAVSO).

1. Introduction

The Journal of the American Association of Variable Star Observers (JAAVSO) was established in 1972 as “a place where professional and non-professional astronomers can publish papers on research of interest to theobserver”(Mayall1972).Mayallwentontowritethat“thenewjournalwouldincludeAbstractsofpaperspresentedatAAVSOmeetings,variousCommitteereports,MinutesoftheMeetingsoftheAAVSO’sCouncil,Observer’sTotals,andBookReviews.”Additionalinsightsconcerningtheformationanddevelopmentof JAAVSO are discussed in theAAVSO’s centennial history (Williams andSaladyga2011).ThecontentofJAAVSOhasevolvedoverrecentyears,nowcontaininglessofthebusinessandmoreofthescholarshipoftheorganization. ThecurrentauthorsandreadersofJAAVSOareamixtureofamateurandprofessionalastronomers.Theseindividualshaveanabidinginterestincelestialphenomenawhichvaryinbrightnessandcolor.ThekindsofdatapresentedinJAAVSOmanuscriptshavechangedovertime.Historically,thedataprimarilywere visual or photographic.At present, data may be visual, photoelectric,or CCD-based. Both the precision and accuracy of the published data haveimprovedwithtime.SufficeittosaythattheauthorsofJAAVSOpapersareavariedandtalentedpopulation. Onthewhole,andcertainlyhistorically,JAAVSOpapersdwelledmoreondata acquisition and data presentation. Data interpretation is not pursued totheextentonefindsintheprofessionaljournals.ItisimportantthattherebeajournalsuchasJAAVSOforitprovidesanopportunitytoabroadercommunitytowriteandtopublishusefulandqualityresearch.

2. Method

TheAstrophysicsDataSystem(ADS)isheadquarteredattheSmithsonianAstrophysical Observatory at Harvard. It is funded by NASA and contains

Landolt, JAAVSO Volume 40, 2012 1033

bibliographic databases, is a digital library, thereby providing access toastronomical informationto theworldvia theWorldWideWeb.Oncein theADS,andintheJournal/Volume/Pagesection,aparticularjournal’scodecanbeentered;forJAAVSO,thatcodeis“JAVSO.”Next,thedesiredjournalvolumenumbercanbeentered.ThisstepleadstoQueryResultswhichlistthepapersintheirorderofappearanceinthespecifiedvolume.TheexistenceoftheletterC indicates that thearticlewascited.Clickingon theCbringsup thecitingarticles,whosenumbersthenmaybecounted. IttranspiresthattheADSdoesnotindexallarticlesinagivenvolumeinits article, or paper, count.Two volumes, numbers one and nineteen (whichappearedin1972and1990,respectively),werecarefullysearchedinaneffortto ascertain which titles were not included by theADS. In volume one, theTreasurer’sReport,ObserverTotals,andCommitteeReportswerenotindexedasarticles.Similarly,involumenineteen,theIntroductiontothevolume,thelistingofthepapersatFirstEuropeanMeetingoftheAAVSO,theMinutesoftheAnnualMeeting,theDirector’sannualreport,theCommitteeReports,andtheTreasurer’sreportwerenotidentifiedbytheADS.Allthesewrittenitemshavethecharacteristicthat theyarenotastronomicalresearcharticles,hencea likely reason for omission from theADS index count.Another reason forinclusionoromissionis that thedecisiontoincludeornot includedependedonthedecisionmaker,differentfromtimetotime.Thisstudywaslimitedtopaperscontainingastronomicaldata. This exercise reviewed the thirty-nine volumes of JAAVSO which werepublishedintheinterval1972through2010.Thereview,thecountingofthecitations, of the authored articles identified by theADS, was completed onOctober,28,2011. Afilewascreatedwhosefunctionwas tocontainacountof thenumberoftimeseachpaperinagivenvolumewascited.Thisfilecontainedamatrixconstructed with the volumes listed in the row, and the possible number ofcitations, from zero to n, listed in the column. The matrix was filled in bytabulating the citations present, or not, if there were none.As an example,volume one contained thirty-one articles, as defined by theADS, of whichtwentypapersneverwerecited,fivepaperswerecitedonce,fourpaperswerecitedtwice,onepaperwascitedthreetimes,andonepaperwascitedfourtimes,foratotaloftwentycitationsforthevolume.

3. Results

SomeaspectsofthisinvestigationhavebeentabulatedinTable1.TheTablecontainsthefollowinginformation:thevolumenumberinthefirstcolumn,theyearofpublicationinthesecondcolumn,thenumberofpaperswhichappearedinthevolumeincolumnthree,andthetotalnumberofcitationsreceivedbythepapers in thatvolume incolumn four.Column fivecontains thenumber


of citations due to JAAVSO authors for a given volume, or, another way ofdescribingit,columnfivegivesthenumberofcitationsincolumnfourwhicharebyJAAVSOauthors.Thelastcolumnprovidesthepercentageofthecitationswhich were due to JAAVSO authors. This column is of interest because itindicateswhetheronlyindividualswhopublishinJAAVSOarecitingJAAVSOpapers. The goal of this table is to compare the number of citations by theastronomicalcommunityasafunctionofvolume,withthenumberofcitationsbyJAAVSOauthors. The information tabulated in Table 1 indicates that 1,545 papers werepublishedinJAAVSOoveritsfirstthirty-nineyears,arateof39.6paperspervolume.Those1,545papershavebeencited1,296times,or,0.84citationsperpaper. Ofthetotal1,296citations,464,or35.8%,werecitationsbyotherJAAVSOauthors.And,64.2%,abouttwo-thirds,ofallcitationstoJAAVSOpaperscamefromthegreaterastronomicalcommunity.Atotalof1,296citationsinthirty-ninevolumesleadsto33.2citationspervolume. The last column in Table 1 provides the percentage of JAAVSO authorcitationsforeachvolume.Ontheaverage,37%ofthecitationstopapersinagivenvolumearebyJAAVSOauthors. Eighteenpapersinthesethirty-ninevolumeswerecitedtenormoretimes.Thepaperwiththemostcitations,nineteen,wasbyPercy,et al.,1985,JAAVSO,vol.14,p.1.Appendix1liststheeighteenpapersinchronologicalorder,andwhichwerecitedatleasttentimes,throughOctober28,2011.Thenumberinbrackets foreach listedpaperprovides thecitationcount for thatpaper.Thepurposeinlistingthemostcitedpapersistoshowthebreadthoftheprojectsfound useful by the user community. It should be emphasized that a smallnumberofcitationsdoesnotmeanthatapaperhasnovalue.Indeed,suchapaper’scontentmaybecrucialtoaciter’sownresearch. Insummary,onecansaythatthearticles,thepapers,whichappearintheissuesofJAAVSO,arereadby,andarecitedby,researchersacrosstheamateurandprofessionalcommunity.

References

Mayall,M.M.1972,J. Amer. Assoc. Var. Star Obs.,1,1.Williams,T.R.,andSaladyga,M.2011,Advancing Variable Star Astronomy:


Landolt, JAAVSO Volume 40, 2012 1035

Vol. Year Number Total Number Percent of Papers Number of JAAVSO JAAVSO of Cites Cites Cites

Table1.CitationcountsofpaperspublishedinJAAVSO,volumes1through39.

1 1972 31 20 13 65.0 2 1973 25 41 23 56.0 3 1974 20 40 11 27.5 4 1975 12 13 4 30.8 5 1976 33 30 6 20.0 6 1977 36 19 7 36.8 7 1978 45 44 12 27.3 8 1979 42 20 12 60.0 9 1980 39 24 12 50.0 10 1981 52 40 20 50.0 11 1982 35 22 5 22.7 12 1983 29 11 6 54.5 13 1984 30 5 2 40.0 14 1985 31 49 22 44.9 15 1986 62 68 45 66.2 16 1987 35 31 18 58.1 17 1988 39 40 18 45.0 18 1989 45 54 19 35.2 19 1990 47 42 9 21.4 20 1991 76 47 18 38.3 21 1992 60 83 31 37.3 22 1993 32 48 8 16.7 23 1994 15 12 6 50.0 24 1995 13 17 4 23.5 25 1996 45 41 16 39.0 26 1997 30 45 10 22.2 27 1998 14 33 7 21.2 28 1999 44 61 15 24.6 29 2000 56 48 8 16.7 30 2001 37 29 6 20.7 31 2002 45 36 7 19.4 32 2003 25 23 3 13.0 33 2004 58 48 18 37.5 34 2005 43 16 11 68.8 35 2006 100 23 9 39.1 36 2007 23 11 7 63.6 37 2008 43 25 5 20.0 38 2009 36 19 6 31.6 39 2010 62 18 5 27.8


Appendix 1Papers published in JAAVSO having the most citations. The papers are listed in chronological order. The number in brackets for each listed paper provides the citation count for that paper.

JAAVSO,2,52,1973[11] Dinerstein,H.,“VXSagittarii:AVariableatManyWavelengths.”JAAVSO,10,1,1981[16] Stanton,R.H.,“PhotoelectricMeasuresofAAVSOComparisonStarSequences—PartTwo.”JAAVSO,14,1,1985[19] Percy,J.R.,Fabro,V.A.,andKeith,D.W.,“TheApplicationofVisualObservationstotheStudy

ofaSmallAmplitudeVariableStar:RhoCassiopeiae.”JAAVSO,15,243,1986[15] Belserene,E.P.,“O–CbyComputer.”JAAVSO,17,34,1988[10] Kiplinger,A.L.,Mattei,J.A.,Danskin,K.H.,andMorgan,J.E.,“Low-amplitudelong-term

modulationsresemblingsolarcyclesinSSCygni.”JAAVSO,21,42,1992[10] Wing,R.F.,“Three-ColorNarrow-BandPhotoelectricPhotometryofRedVariables.”JAAVSO,21,111,1992[11] Samolyk,G.,“APeriodUpdatefortheFiveEclipsingBiinaryStars:SSAri,TYBoo,DFHya,

ZLep,andTYUMa.”JAAVSO, 22,105,1993[18] Oppenheimer,B.D.,andMattei, J.A.,“AnalysisofLong-TermAAVSOObservationsofRS

Ophiuchi.”JAAVSO, 24,106,1995[10] Mattei,J.A.,andFoster,G.,“DramaticPeriodDecreaseinTUrsaeMinoris.”JAAVSO,26,115,1997[11] Hoffleit,D.,“HistoryoftheDiscoveryofMiraStars.”JAAVSO,26,57,1997[11] Mattei,J.A.,“IntroducingMiraVariables.”JAAVSO,27,101,1998[14] Turner,D.G.,“MonitoringtheEvolutionofCepheidVariables.”JAAVSO,27,97,1998[14] Karovska,M.,Carilli,C.L.,andMattei,J.A.,“PossibleJetFormationintheSymbioticSystem

CHCyg.”JAAVSO,28,5,1999[14] Turner,D.G.,Horsford,A.J.,andMacMillan,J.D.,“MonitoringCepheidPeriodChangesfrom

SaintMary’sUniversity.”JAAVSO,31,27,2002[14] Zijlstra,A.A.,andBedding,T.R.,“PeriodEvolutioninMiraVariables.”JAAVSO,32,89,2003[11] Sokoloski,J.L.,“SymboticStarsasLaboratoriesfortheStudyofAccretionandJets:ACallfor

OpticalMonitoring.”JAAVSO,33,9,2004[17] Percy,J.R.,andMohammed,F.,“Self-CorrelationStudiesofRVTauriVariablesandRelated

Objects.”JAAVSO,37,90,2008[11] Majaess, D. J., Turner, D. G., Lande, D. J., and Moncrieff, K. E, “The Exciting Star of the

Berkeley59/CepheusOB4ComplexandOtherChanceVariableStarDiscoveries.”

Abstracts, JAAVSO Volume 40, 2012 1037

Abstracts of Papers and Posters Presented at the Joint Meeting of the Society for Astronomical Sciences and the American Association of Variable Star Observers (AAVSO 101st Spring Meeting), Held in Big Bear Lake, California, May 22–24, 2012

Fast Spectrometer Construction and Testing (Abstract)

John Menke22500 Old Hundred Rd, Barnesville, MD 20838; [email protected]

Abstract This paper describes the construction and operation of a medium resolution spectrometer used in the visual wavelength range. It is homebuilt, but has built in guiding and calibration, is fully remote-operable, and operates at a resolution R = 3000. It features a fast f /3.5 system, which allows it to be used with a fast telescope (18-inch f /3.5) with no Barlow or other optical matching devices.

Observations Using a Bespoke Medium Resolution Fast Spectrograph (Abstract)

John Menke22500 Old Hundred Rd, Barnesville, MD 20838; [email protected]

Abstract Designing and building a medium resolution (R = 3000) spectrograph was the relatively easy part. The really challenging part is learning how to use it: learning the characteristics of the spectrograph, choosing the right kind of astronomical problems, learning the best methods of taking data, and figuring out how to analyze the results. I have used several observing projects to “commission” this system, including measuring the Doppler shifts in several WUMa type stars. I will briefly describe the spectrograph but discuss in more detail the early experiences of using it.

Enhancing the Educational Astronomical Experience of Non-Science Majors With the Use of an iPad and Telescope (Abstract)

Robert M. GillMichael J. BurinCalifornia State University, San Marcos, Physics Department, 333 S.Twin Oaks Valley Rd., San Marcos, CA 92096; [email protected], [email protected]

Abstracts, JAAVSO Volume 40, 20121038

Abstract General Education (GE) classes are designed to broaden the understanding of all college and university students in areas outside their major interest. However, most GE classes are lecture type and do not facilitate hands-on experimental or observational activities related to the specific subject matter. Utilizing several astronomy application programs (apps), currently available for the iPad and iPhone, in conjunction with a small inexpensive telescope allows students unique hands-on experiences to explore and observe astronomical objects and concepts independently outside of class. These activities enhance the student’s overall GE experience in a unique way not possible prior to the development of this technology.

The Rotational Period of the Sun Using the Doppler Shift of the Hα Spectral Line (Abstract)

Robert M. GillCalifornia State University, San Marcos, Physics Department, 333 S.Twin Oaks Valley Rd., San Marcos, CA 92096; [email protected]

Abstract The fact that the sun rotates is obvious by observing the daily motion of sunspots. The overall sunspot movement to the west is a result of this solar rotation. However, solar rotation can also be determined by observing the solar spectrum at the solar limbs. The absorption lines in the spectrum will display a Doppler shift since the east limb is coming toward the observer and the west limb is moving away. The velocity of the limb, relative to the observer, can be determined from these spectral line shifts. Knowing the solar radius, the rotational period can be calculated.

A Single Beam Polarimeter (Poster abstract)

Jerry D. Horne3055 Lynview Drive, San Jose, CA 95148; [email protected]

Abstract As astronomical polarimetry is an emerging field of study for amateur astronomy, the background, theory, and instrumentation of astronomical polarimetry is reviewed. Additionaly, the design and construction of a simple single beam polarimeter is presented, together with the results of its initial calibration.

Index, JAAVSO Volume 40, 2012 1039

Index to Volume 40

AuthorAhrendts,Gary,andShelbyDelos,TimothyBaker LightCurveofMinorPlanet1026Ingrid(Posterabstract) 423Anon. 100thAnnualMeetingSchedule 15 100thSpringMeetingSchedule 8 GroupPhotographTakenatthe100thSpringMeeting 4 GroupPhotographTakenatthe100thAnnualMeeting 9 IndextoVolume40 1039 KeytotheCoverPhotographs 3 Listof100thAnnualMeetingParticipants 11 Listof100thSpringMeetingParticipants 6 ThePaperSessions—photographsofthepresenters 16Baker,Timothy,andShelbyDelos,GaryAhrendts LightCurveofMinorPlanet1026Ingrid(Posterabstract) 423Bakos,Gaspar PlanetHuntingWithHATNetandHATSouth(Abstract) 241Balam,D.D.,inDavidG.Turneret al. MembershipofthePlanetaryNebulaAbell8intheOpenClusterBica6and ImplicationsforthePNDistanceScale(Posterabstract) 423Baldwin,MarvinE.,andDavidB.Williams,GerardSamolyk TheVisualEraoftheAAVSOEclipsingBinaryProgram 180BarnesIII,ThomasG. InterferometryandtheCepheidDistanceScale 256Bauer,Thilo,andErnstPollmann InternationalObservingCampaign:PhotometryandSpectroscopyofPCygni 894Beaman,BarryB.,andMichaelT.Svec Illinois—WhereAstronomicalPhotometryGrewUp 141Benn,David Algorithms+Observations=VStar 852Billings,Gary,inAaronPriceet al. HighSpeedUBVPhotometryofeAurigae’s2009–2011Eclipse(Posterabstract) 418Böhme,Dietmar IsMPGeminorumanEclipsingBinaryWithaVeryLongPeriod? 973Bonaro,Michael,inEdwardF.Guinanet al. EclipsingBinariesThatDon’tEclipseAnymore:theStrangeCaseoftheOnce (andFuture?)EclipsingBinaryQXCassiopeiae(Abstract) 417Borsato,LucainMarioDamassoet al. VSXJ071108.7+695227:aNewlyDiscoveredShort-periodEclipsingBinary 945Boyd,David APracticalApproachtoTransformingMagnitudesontoaStandardPhotometricSystem 990 AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars 295Bracher,Katherine AnneS.Young:ProfessorandVariableStarObserverExtraordinaire 24Broens,Eric,inPatrickWilset al. The“WerkgroepVeranderlijkeSterren”ofBelgium 164Buil,Christian,inRobinLeadbeateret al. HighCadenceMeasurementofNeutralSodiumandPotassiumAbsorptionDuringthe 2009–2011EclipseofeAurigae 729Buil,Christian,inBenjaminMauclaireet al. HaSpectralMonitoringofeAurigae2009–2011Eclipse 718Burin,MichaelJ.,andRobertM.Gill EnhancingtheEducationalAstronomicalExperienceofNon-ScienceMajorsWiththe UseofaniPadandTelescope(Abstract) 1037

Index, JAAVSO Volume 40, 20121040Cahill,MariaJ. TheStarsBelongtoEveryone:AstronomerandScienceWriterHelenSawyerHogg(1905–1993) 31Calcidese,PaoloinMarioDamassoet al. VSXJ071108.7+695227:aNewlyDiscoveredShort-periodEclipsingBinary 945Camargo,Nico AnArtist’sNoteonArtinScience 867Cenadelli,DavideinMarioDamassoet al. VSXJ071108.7+695227:aNewlyDiscoveredShort-periodEclipsingBinary 945Ciocca,Marco,andEthanE.Kilgore,WestleyW.Williams AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData(Posterabstract) 433Clayton,GeoffreyC. WhatAretheRCoronaeBorealisStars? 539Cole,GaryM. PolarimetryofeAurigae,FromNovember2009toJanuary2012 787Croll,Bryce HowAmateursCanContributetotheFieldofTransitingExoplanets 456Damasso,Mario,andDavideCenadelli,PaoloCalcidese,LucaBorsato,ValentinaGranata, ValerioNascimbeni VSXJ071108.7+695227:aNewlyDiscoveredShort-periodEclipsingBinary 945Delos,Shelby,andGaryAhrendts,TimothyBaker LightCurveofMinorPlanet1026 Ingrid(Posterabstract) 423dePonthière,Pierre,andJean-FrançoisLeBorgne,F.Fumagalli,Franz-JosefHanbsch, TomKrajci,J-M.Llapasset,KennethMenzies,MarcoNobile,RichardSabo GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis 904Devinney,EdwardJ.,andEdwardF.Guinan,ScottG.Engle EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers 467Drake,JeremyJ. Stars,Planets,andtheWeather:ifYouDon’tLikeItWaitFiveBillionYears(Abstract) 425Dyck,GeraldP. TheVariableStarObservationsofFrankE.Seagrave(Abstract) 223Eggenstein,Heinz-Bernd,inBrianK.Kloppenborget al. ADemonstrationofAccurateWide-fieldV-bandPhotometryUsingaConsumer-grade DSLRCamera 815Engle,ScottG.,andEdwardF.Guinan,EdwardJ.Devinney EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers 467Engle,ScottG.,inEdwardF.Guinanet al. EclipsingBinariesThatDon’tEclipseAnymore:theStrangeCaseoftheOnce (andFuture?)EclipsingBinaryQXCassiopeiae(Abstract) 417French,LindaM. JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars 120Fröschlin,C.,inMatthewR.Templetonet al. NewLifeforOldData:DigitizationofDataPublishedintheHarvard Annals(Abstract) 429Fu,Rong,andJohnR.Percy ThePulsationPeriodoftheHotHydrogen-DeficientStarMVSgr 900Fumagalli,F.,inPierredePonthièreet al. GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis 904Furgoni,Riccardo VariabilityTypeDeterminationandHighPrecisionEphemerisforNSVS7606408 955Gaensicke,BorisT.,andPaulaSzkody CataclysmicVariables 563Gaensicke,BorisT.,inPaulaSzkodyet al. Twenty-EightYearsofCVResultsWiththeAAVSO 94García,JaimeRuben ThePulsationalBehavioroftheHighAmplitudedScutiStarRSGruis 272Garnavich,Peter ACenturyofSupernovae 598

Index, JAAVSO Volume 40, 2012 1041Garrel,Thierry,inRobinLeadbeateret al. HighCadenceMeasurementofNeutralSodiumandPotassiumAbsorptionDuringthe 2009–2011EclipseofeAurigae 729Garrel,Thierry,inBenjaminMauclaireet al. HaSpectralMonitoringofeAurigae2009–2011Eclipse 718Gary,BruceL.,inAaronPriceet al. HighSpeedUBVPhotometryofeAurigae’s2009–2011Eclipse(Posterabstract) 418Geise,KathleenM.,andRobertE.Stencel,NadineNamset,DavidHarrington,JeffreyKuhn EclipseSpectropolarimetryoftheeAurigaeSystem 767Georgalas,Byron,inGrigorisMaraveliaset al. ReportFromtheeAurigaeCampaigninGreece 679GEOSAssociationinFranz-JosefHambschet al. TheGEOSAssociationofVariableStarObservers(Abstract) 177Gill,RobertM. TheRotationalPeriodoftheSunUsingtheDopplerShiftoftheHaSpectralLine(Abstract) 1038Gill,RobertM.,andMichaelJ.Burin EnhancingtheEducationalAstronomicalExperienceofNon-ScienceMajorsWiththe UseofaniPadandTelescope(Abstract) 1037Gingerich,Owen CentennialHighlightsinAstronomy 438Gorodenski,StanleyA. SpectroscopicResultsFromBlueHillsObservatoryofthe2009–2011EclipseofeAurigae 743Gorodenski,StanleyA.,inRobinLeadbeateret al. HighCadenceMeasurementofNeutralSodiumandPotassiumAbsorptionDuringthe 2009–2011EclipseofeAurigae 729Gott,Andrew,inSaiGouravajhalaet al. BrightNewType-IaSupernovainthePinwheelGalaxy(M101):PhysicalProperties ofSN2011feFromPhotometryandSpectroscopy(Posterabstract) 419Gouravajhala,Sai,andEdwardF.Guinan,LouisStrolger,AndrewGott BrightNewType-IaSupernovainthePinwheelGalaxy(M101):PhysicalProperties ofSN2011feFromPhotometryandSpectroscopy(Posterabstract) 419Granata,ValentinainMarioDamassoet al. VSXJ071108.7+695227:aNewlyDiscoveredShort-periodEclipsingBinary 945Griffin,R.Elizabeth,andRobertE.Stencel UV-Blue(CCD)andHistoric(Photographic)SpectraofeAurigae—Summary 714Gross,John,andDirkTerrell GSC4552-1643:aWUMaSystemWithCompleteEclipses 941Guetter,HarryH.,inFrederickJohnVrbaet al. StatusoftheUSNOInfraredAstrometryProgram(Posterabstract) 434Guinan,EdwardF.,andMichaelBonaro,ScottG.Engle,AndrejPrsa EclipsingBinariesThatDon’tEclipseAnymore:theStrangeCaseoftheOnce (andFuture?)EclipsingBinaryQXCassiopeiae(Abstract) 417Guinan,EdwardF.,andScottG.Engle,EdwardJ.Devinney EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers 467Guinan,EdwardF.,inSaiGouravajhalaet al. BrightNewType-IaSupernovainthePinwheelGalaxy(M101):PhysicalProperties ofSN2011feFromPhotometryandSpectroscopy(Posterabstract) 419Guzik,JoyceAnn,inMatthewR.Templetonet al. PreliminaryAnalysisofMOSTObservationsoftheTrapezium(Abstract) 415Hambsch,Franz-Josef IntensiveObservationsofCataclysmic,RRLyrae,andHighAmplitudedScuti (HADS)VariableStars 289 ROAD(RemoteObservatoryAtacamaDesert):IntensiveObservationsofVariableStars 1003Hambsch,Franz-Josef,andJoachimHübscher IntroductiontoBAV(Abstract) 177Hambsch,Franz-Josef,andJean-FrançoisLeBorgne,E.Poretti,GEOSAssociation TheGEOSAssociationofVariableStarObservers(Abstract) 177

Index, JAAVSO Volume 40, 20121042Hanbsch,Franz-Josef,inPierredePonthièreet al. GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis 904Hansen,CarlJ.,andStevenD.Kawaler StellarPulsationTheoryFromArthurStanleyEddingtontoToday(Abstract) 150Hansen,Torsten,inRobinLeadbeateret al. HighCadenceMeasurementofNeutralSodiumandPotassiumAbsorptionDuringthe 2009–2011EclipseofeAurigae 729Harrington,David,inKathleenM.Geiseet al. EclipseSpectropolarimetryoftheeAurigaeSystem 767Hatch,RobertAlan TheHistoryofVariableStars:aFreshLook(Abstract) 151Hautecler,Hubert,inPatrickWilset al. The“WerkgroepVeranderlijkeSterren”ofBelgium 164Henden,ArneA. ContributionsbyCitizenScientiststoAstronomy(Abstract) 239Henden,ArneA.,andStephenE.Levine,DirkTerrell,T.C.Smith,DouglasL.Welch DataRelease3oftheAAVSOAll-SkyPhotometricSurvey(APASS)(Posterabstract) 430Henden,ArneA.,inBrianK.Kloppenborget al. CollaborativeResearchEffortsforCitizenScientists(Posterabstract) 426Henden,ArneA.,inAaronPriceet al. HighSpeedUBVPhotometryofeAurigae’s2009–2011Eclipse(Posterabstract) 418 TheOriginsandFutureoftheCitizenSkyProject 614Henden,ArneA.,inPaulaSzkodyet al. Twenty-EightYearsofCVResultsWiththeAAVSO 94Henden,ArneA.,inMatthewR.Templetonet al. PreliminaryAnalysisofMOSTObservationsoftheTrapezium(Abstract) 415Henden,ArneA.,inDavidG.Turneret al. AAVSOEstimatesandtheNatureofTypeCSemiregulars:ProgenitorsofTypeII Supernovae(Abstract) 415 MembershipofthePlanetaryNebulaAbell8intheOpenClusterBica6and ImplicationsforthePNDistanceScale(Posterabstract) 423Henden,ArneA.,inFrederickJohnVrbaet al. StatusoftheUSNOInfraredAstrometryProgram(Posterabstract) 434Herbst,William TheVariabilityofYoungStellarObjects 448Herbst,William,inMatthewR.Templetonet al. PreliminaryAnalysisofMOSTObservationsoftheTrapezium(Abstract) 415Holmberg,Gustav ANoteontheVariabilityofV538Cassiopeiae 986Hopkins,JeffreyL. TheInternationaleAurigaeCampaign2009PhotometryReport 633Hopkins,JeffreyL.,andBrianK.Kloppenborg,RobertE.Stencel AnAnalysisoftheLong-termPhotometricBehaviorofeAurigae 647Horne,JerryD. ASingleBeamPolarimeter(Posterabstract) 1038 RSSagittae:theSearchforEclipses 278Howe,Rodney SolarCycle24—WillItBeUnusuallyQuiet?(Abstract) 435Howell,SteveB.,inPaulaSzkodyet al. Twenty-EightYearsofCVResultsWiththeAAVSO 94Hübscher,Joachim,andFranz-JosefHambsch IntroductiontoBAV(Abstract) 177Hull,Tony AnAppreciationofClintonB.FordandtheAAVSOofFiftyYearsAgo 203Hurdis,DavidA.,andTomKrajci SecularVariationoftheModeAmplitude-RatiooftheDouble-ModeRRLyraeStar NSVS5222076,Part2 268

Index, JAAVSO Volume 40, 2012 1043Jones,Albert,andStanWalker TheRASNZVariableStarSectionandVariableStarsSouth 168Kardasis,Emmanuel,inGrigorisMaraveliaset al. ReportFromtheeAurigaeCampaigninGreece 679Karlsson,Thomas V-bandLightCurveAnalysisofeAurigaeDuringthe2009–2011Eclipse 668Karovska,Margarita ImagingVariableStarsWithHST(Abstract) 265Kawaler,StevenD.,andCarlJ.Hansen StellarPulsationTheoryFromArthurStanleyEddingtontoToday(Abstract) 150Kilgore,EthanE.,andMarcoCiocca,WestleyW.Williams AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData(Posterabstract) 433Kinne,RichardC.S. AnOverviewoftheAAVSO’sInformationTechnologyInfrastructureFrom1967to1997 208 VariableStarObservingWiththeBradfordRoboticTelescope(Abstract) 435Kiss,LászlóL.,andJohnR.Percy Non-MiraPulsatingRedGiantsandSupergiants 528Kiyota,Seiichiro HistoryofAmateurVariableStarObservationsinJapan(Posterabstract) 178Kloppenborg,BrianK. Spots,Eclipses,andPulsation:theInterplayofPhotometryandOptical InterferometricImaging(Abstract) 266Kloppenborg,BrianK.,andJeffreyL.Hopkins,RobertE.Stencel AnAnalysisoftheLong-termPhotometricBehaviorofeAurigae 647Kloppenborg,BrianK.,andRogerPieri,Heinz-BerndEggenstein, GrigorisMaravelias,TomPearson ADemonstrationofAccurateWide-fieldV-bandPhotometryUsingaConsumer-grade DSLRCamera 815Kloppenborg,BrianK.,andAaronPrice,RebeccaTurner,ArneA.Henden,RobertE.Stencel CollaborativeResearchEffortsforCitizenScientists(Posterabstract) 426Kloppenborg,BrianK.,inAaronPriceet al. HighSpeedUBVPhotometryofeAurigae’s2009–2011Eclipse(Posterabstract) 418 TheOriginsandFutureoftheCitizenSkyProject 614Kolenberg,Katrien RRLyraeStars:CosmicLighthousesWithaTwist 481Kolman,RogerS.,andMikeSimonsen WalkingWithAAVSOGiants—aPersonalJourney(1960s) 189Koutoulaki,Maria,inGrigorisMaraveliaset al. ReportFromtheeAurigaeCampaigninGreece 679Krajci,Tom,andDavidA.Hurdis SecularVariationoftheModeAmplitude-RatiooftheDouble-ModeRRLyraeStar NSVS5222076,Part2 268Krajci,Tom,inPierredePonthièreet al. GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis 904Krisciunas,Kevin TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview 334Kuhn,Jeffrey,inKathleenM.Geiseet al. EclipseSpectropolarimetryoftheeAurigaeSystem 767Landolt,ArloU. TheAcquisitionofPhotometricData 355 TheCitationofManuscriptsWhichHaveAppearedinJAAVSO 1032Lane,DavidJ.,andR.Ouyed,D.Leahy,DouglasL.Welch TheHuntfortheQuark-Nova;aCallforObservers(Abstract) 425Lane,DavidJ.,inDavidG.Turneret al. MembershipofthePlanetaryNebulaAbell8intheOpenClusterBica6and ImplicationsforthePNDistanceScale(Posterabstract) 423

Index, JAAVSO Volume 40, 20121044Larsen,Kristine TheEffectofOnlineSunspotDataonVisualSolarObservers 374 Flares,Fears,andForecasts:PublicMisconceptionsAbouttheSunspotCycle 407 ReminiscencesontheCareerofMarthaStahrCarpenter:Betweenarockand(Several)HardPlaces 51 VariableStarsandConstantCommitments:theStellarCareerofDorritHoffleit 44LeBorgne,Jean-François,inPierredePonthièreet al. GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis 904LeBorgne,Jean-François,inFranz-JosefHambschet al. TheGEOSAssociationofVariableStarObservers(Abstract) 177Leadbeater,Robin,andChristianBuil,ThierryGarrel,StanleyA.Gorodenski, TorstenHansen,LotharSchanne,RobertE.Stencel,BertholdStober,OlivierThizy HighCadenceMeasurementofNeutralSodiumandPotassiumAbsorptionDuringthe 2009–2011EclipseofeAurigae 729Leadbeater,Robin,inBenjaminMauclaireet al. HaSpectralMonitoringofeAurigae2009–2011Eclipse 718Leahy,D.,inDavidJ.Laneet al. TheHuntfortheQuark-Nova;aCallforObservers(Abstract) 425Levine,StephenE.,inArneA.Hendenet al. DataRelease3oftheAAVSOAll-SkyPhotometricSurvey(APASS)(Posterabstract) 430Llapasset,J-M.,inPierredePonthièreet al. GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis 904Lopez,Alain,inBenjaminMauclaireet al. HaSpectralMonitoringofeAurigae2009–2011Eclipse 718Los,EdwardJ. ProgressReportforAdaptingAPASSDataReleasesfortheCalibrationofHarvardPlates 396Luberda,Grant,andWayneOsborn NewLightCurveforthe1909OutburstofRTSerpentis 887Luginbuhl,ChristianB.,inFrederickJohnVrbaet al. StatusoftheUSNOInfraredAstrometryProgram(Posterabstract) 434Lunn,Martin KingCharles’Star:AMultidisciplinaryApproachtoDatingtheSupernova KnownasCassiopeiaA(Abstract) 150MacNeil,Drew,inJohnR.Percyet al. HighSchoolStudentsWatchingStarsEvolve(Abstract) 416Majaess,DanielJ.,inDavidG.Turneret al. MembershipofthePlanetaryNebulaAbell8intheOpenClusterBica6and ImplicationsforthePNDistanceScale(Posterabstract) 423Maravelias,Grigoris,andEmmanuelKardasis,Iakovos-MariosStrikis,ByronGeorgalas, MariaKoutoulaki ReportFromtheeAurigaeCampaigninGreece 679Maravelias,Grigoris,inBrianK.Kloppenborget al. ADemonstrationofAccurateWide-fieldV-bandPhotometryUsingaConsumer-grade DSLRCamera 815Marengo,Massimo,andLeeAnneWillson Miras 516Mattei,JanetA.,inPaulaSzkodyet al. Twenty-EightYearsofCVResultsWiththeAAVSO 94Mauclaire,Benjamin,andChristianBuil,ThierryGarrel,RobinLeadbeater,AlainLopez HaSpectralMonitoringofeAurigae2009–2011Eclipse 718Meech,KarenJ. AnAmateur-ProfessionalInternationalObservingCampaignfortheEPOXIMission: NewInsightsIntoComets(Abstract) 422Meema-Coleman,Leila,inJohnR.Percyet al. HighSchoolStudentsWatchingStarsEvolve(Abstract) 416Melillo,FrankJ. PhotoelectricPhotometryofeAurigaeDuringthe2009–2011EclipseSeason 695

Index, JAAVSO Volume 40, 2012 1045Menke,John FastSpectrometerConstructionandTesting(Abstract) 1037 ObservationsUsingaBespokeMediumResolutionFastSpectrograph(Abstract) 1037Menzies,Kenneth,inPierredePonthièreet al. GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis 904Mills,O.Frank,andWayneOsborn TheRossVariableStarsRevisited.II 929Moncrieff,K.,inDavidG.Turneret al. AAVSOEstimatesandtheNatureofTypeCSemiregulars:ProgenitorsofTypeII Supernovae(Abstract) 415Moore,Caroline TheWorld’sStrangestSupernovaMayNotBeaSupernovaAtAll(Abstract) 421Morenz,Karen,inJohnR.Percyet al. HighSchoolStudentsWatchingStarsEvolve(Abstract) 416Motta,Mario AdverseHealthEffectsofNighttimeLighting 380Mukadam,AnjumS.,inPaulaSzkodyet al. Twenty-EightYearsofCVResultsWiththeAAVSO 94Munari,Ulisse ClassicalandRecurrentNovae 582 SymbioticStars 572Munn,JeffreyA.,inFrederickJohnVrbaet al. StatusoftheUSNOInfraredAstrometryProgram(Posterabstract) 434Nascimbeni,ValerioinMarioDamassoet al. VSXJ071108.7+695227:aNewlyDiscoveredShort-periodEclipsingBinary 945Namset,Nadine,inKathleenM.Geiseet al. EclipseSpectropolarimetryoftheeAurigaeSystem 767Nobile,Marco,inPierredePonthièreet al. GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis 904Osborn,Wayne FrankElmoreRossandHisVariableStarDiscoveries 133Osborn,Wayne,andGrantLuberda NewLightCurveforthe1909OutburstofRTSerpentis 887Osborn,Wayne,andO.FrankMills TheRossVariableStarsRevisited.II 929Otero,Sebastian DataEvolutioninVSX:MakingaGoodThingBetter(Abstract) 431Ouyed,R.,inDavidJ.Laneet al. TheHuntfortheQuark-Nova;aCallforObservers(Abstract) 425Patterson,Joseph CataclysmicVariablesintheBackyard(Abstract) 240Paxson,KevinB. DigitalArchiving:WherethePastLivesAgain 360Paxson,KevinB.,andAaronPrice TheAAVSO2011DemographicandBackgroundSurvey 1010Paxson,KevinB.,inMatthewR.Templetonet al. NewLifeforOldData:DigitizationofDataPublishedintheHarvard Annals(Abstract) 429Pazmino,John TheWorldScienceFestival(Abstract) 428PearsonIII,RichardL.,andRobertE.Stencel ModelingtheDiskintheeAUrigaeSystem:aBriefReviewWithProposedNumericalSolutions 802Pearson,Tom,inBrianK.Kloppenborget al. ADemonstrationofAccurateWide-fieldV-bandPhotometryUsingaConsumer-grade DSLRCamera 815Percy,JohnR. TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext 109

Index, JAAVSO Volume 40, 20121046 AboutThis100thAnniversaryIssue 1 HighlightingeAurigaeandCitizenSky 609 Introduction:VariableStarAstronomyinthe21stCentury 442 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics 230Percy,JohnR.,andRongFu ThePulsationPeriodoftheHotHydrogen-DeficientStarMVSgr 900Percy,JohnR.,andLászlóL.Kiss Non-MiraPulsatingRedGiantsandSupergiants 528Percy,JohnR.,andDrewMacNeil,LeilaMeema-Coleman,KarenMorenz HighSchoolStudentsWatchingStarsEvolve(Abstract) 416Pieri,Roger StellarPhotometryWithDSLR:BenchmarkofTwoColorCorrectionTechniques TowardJohnson’sVJandTychoVT 834Pieri,Roger,inBrianK.Kloppenborget al. ADemonstrationofAccurateWide-fieldV-bandPhotometryUsingaConsumer-grade DSLRCamera 815Pollmann,Ernst,andThiloBauer InternationalObservingCampaign:PhotometryandSpectroscopyofPCygni 894Poretti,E.,inFranz-JosefHambschet al. TheGEOSAssociationofVariableStarObservers(Abstract) 177Price,Aaron RaschAnalysisofScientificLiteracyinanAstronomicalCitizenScienceProject(Posterabstract) 427Price,Aaron,andGaryBillings,BruceL.Gary,BrianK.Kloppenborg,ArneA.Henden HighSpeedUBVPhotometryofeAurigae’s2009–2011Eclipse(Posterabstract) 418Price,Aaron,andKevinB.Paxson TheAAVSO2011DemographicandBackgroundSurvey 1010Price,Aaron,andRebeccaTurner,RobertE.Stencel,BrianK.Kloppenborg,ArneA.Henden TheOriginsandFutureoftheCitizenSkyProject 614Price,Aaron,andRebeccaTurner,RyanWyatt TheCitizenSkyPlanetariumTrailer(Posterabstract) 428Price,Aaron,inBrianK.Kloppenborget al. CollaborativeResearchEffortsforCitizenScientists(Posterabstract) 426Prsa,Andrej,inEdwardF.Guinanet al. EclipsingBinariesThatDon’tEclipseAnymore:theStrangeCaseoftheOnce (andFuture?)EclipsingBinaryQXCassiopeiae(Abstract) 417Ragland,Sam ProbingMiraAtmospheresUsingOpticalInterferometricTechniques(Abstract) 265Richards,Tom TheVariableStarsSouthEclipsingBinaryDatabase 983Richmond,MichaelW.,andHoraceA.Smith BVRIPhotometryofSN2011feinM101 872Riggs,Jamie AGeneralizedLinearMixedModelforEnumeratedSunspots(Abstract) 436Rosvick,JoanneM.,inDavidG.Turneret al. MembershipofthePlanetaryNebulaAbell8intheOpenClusterBica6and ImplicationsforthePNDistanceScale(Posterabstract) 423Rupp,Andrew,inMatthewR.Templetonet al. NewLifeforOldData:DigitizationofDataPublishedintheHarvard Annals(Abstract) 429Rutherford,ThomasP. SmallTelescopeInfraredPhotometryoftheeAurigaeEclipse 704Sabo,Richard,inPierredePonthièreet al. GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis 904Sakuma,Seiichi StarWatchingPromotedbytheMinistryoftheEnvironment,Japan 391Saladyga,Michael MargaretW.MayallintheAAVSOArchives(Abstract) 92

Index, JAAVSO Volume 40, 2012 1047Saladyga,Michael,andElizabethO.Waagen ProfessionalAstronomersinServicetotheAAVSO(Posterabstract) 223Saladyga,Michael,inMatthewR.Templetonet al. NewLifeforOldData:DigitizationofDataPublishedintheHarvard Annals(Abstract) 429Samolyk,Gerard RecentMaximaof55ShortPeriodPulsatingStars 923 RecentMinimaof150EclipsingBinaryStars 975Samolyk,Gerard,andDavidB.Williams,MarvinE.Baldwin TheVisualEraoftheAAVSOEclipsingBinaryProgram 180Schanne,Lothar,inRobinLeadbeateret al. HighCadenceMeasurementofNeutralSodiumandPotassiumAbsorptionDuringthe 2009–2011EclipseofeAurigae 729Scovil,CharlesE. VariableStarObserversIHaveKnown 196Short,C.,inDavidG.Turneret al. AAVSOEstimatesandtheNatureofTypeCSemiregulars:ProgenitorsofTypeII Supernovae(Abstract) 415SigismondiSapienza,Costantino dScorpii2011Periastron:VisualandDigitalPhotometricCampaign(Posterabstract) 419Simonsen,Mike AAVSOnet:theRoboticTelescopeNetwork(Posterabstract) 432 TheZCamPaignEarlyResults(Abstract) 241Simonsen,Mike,andRogerS.Kolman WalkingWithAAVSOGiants—aPersonalJourney(1960s) 189Simonsen,Mike,inPaulaSzkodyet al. Twenty-EightYearsofCVResultsWiththeAAVSO 94Sion,EdwardM.,inPaulaSzkodyet al. Twenty-EightYearsofCVResultsWiththeAAVSO 94Slater,StephanieJ. ExploringtheBreadthandSourcesofVariableStarAstronomers’Astronomy Knowledge:FirstSteps(Abstract) 427Smith,HoraceA. ThingsWeDon’tUnderstandAboutRRLyraeStars 327Smith,HoraceA.,andMichaelW.Richmond BVRIPhotometryofSN2011feinM101 872Smith,T.C.,inArneA.Hendenet al. DataRelease3oftheAAVSOAll-SkyPhotometricSurvey(APASS)(Posterabstract) 430Soderblom,DavidR. Hubble’sFamousPlateof1923:aStoryofPinkPolyethylene 321Speck,AngelaK. VariableStarsandtheAsymptoticGiantBranch:StellarPulsations,DustProduction,andMassLoss 244Stanley,Matthew TheDevelopmentofEarlyPulsationTheory,or,HowCepheidsAreLikeSteamEngines 100Stencel,RobertE. eAurigae—anOverviewofthe2009–2011EclipseCampaignResults 618 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) 239Stencel,RobertE.,andR.ElizabethGriffin UV-Blue(CCD)andHistoric(Photographic)SpectraofeAurigae—Summary 714Stencel,RobertE.,andBrianK.Kloppenborg,JeffreyL.Hopkins AnAnalysisoftheLong-termPhotometricBehaviorofeAurigae 647Stencel,RobertE.,andRichardL.PearsonIII ModelingtheDiskintheeAurigaeSystem:aBriefReviewWithProposedNumericalSolutions 802Stencel,RobertE.,inKathleenM.Geiseet al. EclipseSpectropolarimetryoftheeAurigaeSystem 767Stencel,RobertE.,inBrianK.Kloppenborget al. CollaborativeResearchEffortsforCitizenScientists(Posterabstract) 426

Index, JAAVSO Volume 40, 20121048Stencel,RobertE.,inRobinLeadbeateret al. HighCadenceMeasurementofNeutralSodiumandPotassiumAbsorptionDuringthe 2009–2011EclipseofeAurigae 729Stencel,RobertE.,inAaronPriceet al. TheOriginsandFutureoftheCitizenSkyProject 614Stine,RobertJ.,inMatthewR.Templetonet al. NewLifeforOldData:DigitizationofDataPublishedintheHarvard Annals(Abstract) 429Stober,Berthold,inRobinLeadbeateret al. HighCadenceMeasurementofNeutralSodiumandPotassiumAbsorptionDuringthe 2009–2011EclipseofeAurigae 729Strikis,Iakovos-Marios,inGrigorisMaraveliaset al. ReportFromtheeAurigaeCampaigninGreece 679Strolger,Louis,inSaiGouravajhalaet al. BrightNewType-IaSupernovainthePinwheelGalaxy(M101):PhysicalProperties ofSN2011feFromPhotometryandSpectroscopy(Posterabstract) 419Svec,MichaelT.,andBarryB.Beaman Illinois—WhereAstronomicalPhotometryGrewUp 141Szkody,Paula,andBorisT.Gaensicke CataclysmicVariables 563Szkody,Paula,andAnjumS.Mukadam,BorisT.Gaensicke,JanetA.Mattei,ArneA.Henden, MikeSimonsen,MatthewR.Templeton,ElizabethO.Waagen,GaryWalker,EdwardM.Sion, SteveB.Howell,DeanTownsley Twenty-EightYearsofCVResultsWiththeAAVSO 94Templeton,MatthewR. AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience 348 IntroductiontotheJointAAS-AAVSOScientificPaperSessions 226Templeton,MatthewR.,andJoyceAnnGuzik,ArneA.Henden,WilliamHerbst PreliminaryAnalysisofMOSTObservationsoftheTrapezium(Abstract) 415Templeton,MatthewR.,andMichaelSaladyga,KevinB.Paxson,RobertJ.Stine, C.Fröschlin,AndrewRupp NewLifeforOldData:DigitizationofDataPublishedintheHarvard Annals(Abstract) 429Templeton,MatthewR.,inPaulaSzkodyet al. Twenty-EightYearsofCVResultsWiththeAAVSO 94Terrell,Dirk,andJohnGross GSC4552-1643:aWUMaSystemWithCompleteEclipses 941Terrell,Dirk,inArneA.Hendenet al. DataRelease3oftheAAVSOAll-SkyPhotometricSurvey(APASS)(Posterabstract) 430Thizy,Olivier,inRobinLeadbeateret al. HighCadenceMeasurementofNeutralSodiumandPotassiumAbsorptionDuringthe 2009–2011EclipseofeAurigae 729Tilleman,T.M.,inFrederickJohnVrbaet al. StatusoftheUSNOInfraredAstrometryProgram(Posterabstract) 434Toone,John BritishAstronomicalAssociationVariableStarSection,1890–2011 154Townsley,Dean,inPaulaSzkodyet al. Twenty-EightYearsofCVResultsWiththeAAVSO 94Turner,DavidG. ClassicalCepheidsAfter228YearsofStudy 502Turner,DavidG.,andK.Moncrieff,C.Short,RobertF.Wing,ArneA.Henden AAVSOEstimatesandtheNatureofTypeCSemiregulars:ProgenitorsofTypeII Supernovae(Abstract) 415Turner,DavidG.,andJoanneM.Rosvick,D.D.Balam,ArneA.Henden,DanielJ.Majaess,DavidJ.Lane MembershipofthePlanetaryNebulaAbell8intheOpenClusterBica6and ImplicationsforthePNDistanceScale(Posterabstract) 423Turner,Rebecca,inAaronPriceet al. TheOriginsandFutureoftheCitizenSkyProject 614Turner,Rebecca,inBrianK.Kloppenborget al. CollaborativeResearchEffortsforCitizenScientists(Posterabstract) 426

Index, JAAVSO Volume 40, 2012 1049Turner,Rebecca,andAaronPrice,RyanWyatt TheCitizenSkyPlanetariumTrailer(Posterabstract) 428Valleli,Paul Apollo14RoadTrip(Posterabstract) 223VanLoo,Frans,inPatrickWilset al. The“WerkgroepVeranderlijkeSterren”ofBelgium 164Vrba,FrederickJohn,andJeffreyA.Munn,ChristianB.Luginbuhl,T.M.Tilleman, ArneA.Henden,HarryH.Guetter StatusoftheUSNOInfraredAstrometryProgram(Posterabstract) 434Waagen,ElizabethO. GuidingForcesandJanetA.Mattei 65 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) 222Waagen,ElizabethO.,andMichaelSaladyga ProfessionalAstronomersinServicetotheAAVSO(Posterabstract) 223Waagen,ElizabethO.,inPaulaSzkodyet al. Twenty-EightYearsofCVResultsWiththeAAVSO 94Walker,Gary HaEmissionExtractionUsingNarrowbandPhotometricFilters(Abstract) 432Walker,Gary,inPaulaSzkodyet al. Twenty-EightYearsofCVResultsWiththeAAVSO 94Walker,Stan TheRASNZPhotometrySection,IncorporatingtheAucklandPhotoelectricObservers’ Group(Posterabstract) 177Walker,Stan,andAlbertJones TheRASNZVariableStarSectionandVariableStarsSouth 168Wang,Qian,andLeeAnneWillson WhatMassLossModelingTellsUsAboutPlanetaryNebulae(Abstract) 424Watson,ChristopherL. VSX:theNextGeneration(Abstract) 431Welch,DouglasL. Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds 492Welch,DouglasL.,inArneA.Hendenet al. DataRelease3oftheAAVSOAll-SkyPhotometricSurvey(APASS)(Posterabstract) 430Welch,DouglasL.,inDavidJ.Laneet al. TheHuntfortheQuark-Nova;aCallforObservers(Abstract) 425Welther,BarbaraL. TheLegacyofAnnieJumpCannon:DiscoveriesandCataloguesofVariableStars(Abstract) 92Williams,DavidB.,andMarvinE.Baldwin,GerardSamolyk TheVisualEraoftheAAVSOEclipsingBinaryProgram 180Williams,ThomasR. TheAAVSOWidow—orShouldWeSaySpouse? 77 IntroductiontotheHistoryPaperSessions 20Williams,WestleyW.,andMarcoCiocca,EthanE.Kilgore AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData(Posterabstract) 433Willson,LeeAnne,andMassimoMarengo Miras 516Willson,LeeAnne,andQianWang WhatMassLossModelingTellsUsAboutPlanetaryNebulae(Abstract) 424Wils,Patrick,andEricBroens,HubertHautecler,FransVanLoo The“WerkgroepVeranderlijkeSterren”ofBelgium 164Wing,RobertF.,inDavidG.Turneret al. AAVSOEstimatesandtheNatureofTypeCSemiregulars:ProgenitorsofTypeII Supernovae(Abstract) 415Wyatt,Ryan,andRebeccaTurner,AaronPrice TheCitizenSkyPlanetariumTrailer(Posterabstract) 428

Index, JAAVSO Volume 40, 20121050

SubjectAAVSO TheAAVSO2011DemographicandBackgroundSurvey AaronPriceandKevinB.Paxson 1010 AAVSOEstimatesandtheNatureofTypeCSemiregulars:ProgenitorsofTypeIISupernovae(Abstract) DavidG.Turneret al. 415 TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 TheAAVSOWidow—orShouldWeSaySpouse? ThomasR.Williams 77 AAVSOnet:theRoboticTelescopeNetwork(Posterabstract) MikeSimonsen 432 AboutThis100thAnniversaryIssue JohnR.Percy 1 Algorithms+Observations=VStar DavidBenn 852 AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 AnneS.Young:ProfessorandVariableStarObserverExtraordinaire KatherineBracher 24 Apollo14RoadTrip(Posterabstract) PaulValleli 223 AnAppreciationofClintonB.FordandtheAAVSOofFiftyYearsAgon TonyHull 203 BritishAstronomicalAssociationVariableStarSection,1890–2011 JohnToone 154 CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 CentennialHighlightsinAstronomy OwenGingerich 438 TheCitationofManuscriptsWhichHaveAppearedinJAAVSO ArloU.Landolt 1032 TheCitizenSkyPlanetariumTrailer(Posterabstract) RebeccaTurner,AaronPrice,andRyanWyatt 428 ClassicalandRecurrentNovae UlisseMunari 582 CollaborativeResearchEffortsforCitizenScientists(Posterabstract) BrianK.Kloppenborget al. 426 ContributionsbyCitizenScientiststoAstronomy(Abstract) ArneA.Henden 239 DataEvolutioninVSX:MakingaGoodThingBetter(Abstract) SebastianOtero 431 DataRelease3oftheAAVSOAll-SkyPhotometricSurvey(APASS)(Posterabstract) ArneA.Hendenet al. 430 DigitalArchiving:WherethePastLivesAgain KevinB.Paxson 360 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 TheEffectofOnlineSunspotDataonVisualSolarObservers KristineLarsen 374 ExploringtheBreadthandSourcesofVariableStarAstronomers’AstronomyKnowledge: FirstSteps(Abstract) StephanieJ.Slater 427 Flares,Fears,andForecasts:PublicMisconceptionsAbouttheSunspotCycle KristineLarsen 407

Index, JAAVSO Volume 40, 2012 1051 AGeneralizedLinearMixedModelforEnumeratedSunspots(Abstract) JamieRiggs 436 GuidingForcesandJanetA.Mattei ElizabethO.Waagen 65 HaEmissionExtractionUsingNarrowbandPhotometricFilters(Abstract) GaryWalker 432 HighlightingeAurigaeandCitizenSky JohnR.Percy 609 Hubble’sFamousPlateof1923:aStoryofPinkPolyethylene DavidR.Soderblom 321 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 InternationalObservingCampaign:PhotometryandSpectroscopyofPCygni ErnstPollmannandThiloBauer 894 IntroductiontotheHistoryPaperSessions ThomasR.Williams 20 IntroductiontotheJointAAS-AAVSOScientificPaperSessions MatthewR.Templeton 226 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 TheLegacyofAnnieJumpCannon:DiscoveriesandCataloguesofVariableStars(Abstract) BarbaraL.Welther 92 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics JohnR.Percy 230 MargaretW.MayallintheAAVSOArchives(Abstract) MichaelSaladyga 92 Miras LeeAnneWillsonandMassimoMarengo 516 NewLifeforOldData:DigitizationofDataPublishedintheHarvardAnnals(Abstract) MatthewR.Templetonet al. 429 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 ANoteontheVariabilityofV538Cassiopeiae GustavHolmberg 986 TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 AnOverviewoftheAAVSO’sInformationTechnologyInfrastructureFrom1967to1997 RichardC.S.Kinne 208 ProfessionalAstronomersinServicetotheAAVSO(Posterabstract) MichaelSaladygaandElizabethO.Waagen 223 ProgressReportforAdaptingAPASSDataReleasesfortheCalibrationofHarvardPlates EdwardJ.Los 396 RaschAnalysisofScientificLiteracyinanAstronomicalCitizenScienceProject(Posterabstract) AaronPrice 427 TheRASNZVariableStarSectionandVariableStarsSouth AlbertJonesandStanWalker 168 RecentMaximaof55ShortPeriodPulsatingStars GerardSamolyk 923 RecentMinimaof150EclipsingBinaryStars GerardSamolyk 975 ReminiscencesontheCareerofMarthaStahrCarpenter:BetweenaRockand(Several)HardPlaces KristineLarsen 51 RRLyraeStars:CosmicLighthousesWithaTwist KatrienKolenberg 481

Index, JAAVSO Volume 40, 20121052 SecularVariationoftheModeAmplitude-RatiooftheDouble-ModeRRLyraeStar NSVS5222076,Part2 DavidA.HurdisandTomKrajci 268 SolarCycle24—WillItBeUnusuallyQuiet?(Abstract) RodneyHowe 435 TheStarsBelongtoEveryone:AstronomerandScienceWriterHelenSawyerHogg(1905–1993) MariaJ.Cahill 31 StellarPhotometryWithDSLR:BenchmarkofTwoColorCorrectionTechniquesToward Johnson’sVJandTychoVT RogerPieri 834 ThingsWeDon’tUnderstandAboutRRLyraeStars HoraceA.Smith 327 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222 Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 WalkingWithAAVSOGiants—aPersonalJourney(1960s) RogerS.KolmanandMikeSimonsen 189 The“WerkgroepVeranderlijkeSterren”ofBelgium PatrickWilset al. 164 TheVariableStarObservationsofFrankE.Seagrave(Abstract) GeraldP.Dyck 223 VariableStarObserversIHaveKnown CharlesE.Scovil 196 VariableStarsandConstantCommitments:theStellarCareerofDorritHoffleit KristineLarsen 44 TheVisualEraoftheAAVSOEclipsingBinaryProgram DavidB.Williams,MarvinE.Baldwin,andGerardSamolyk 180 VSX:theNextGeneration(Abstract) ChristopherL.Watson 431 TheZCamPaignEarlyResults(Abstract) MikeSimonsen 241

AAVSO INTERNATIONAL DATABASE AAVSOEstimatesandtheNatureofTypeCSemiregulars:ProgenitorsofTypeIISupernovae(Abstract) DavidG.Turneret al. 415 TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 AAVSOnet:theRoboticTelescopeNetwork(Posterabstract) MikeSimonsen 432 TheAcquisitionofPhotometricData ArloU.Landolt 355 Algorithms+Observations=VStar DavidBenn 852 AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 AnAnalysisoftheLong-termPhotometricBehaviorofeAurigae BrianK.Kloppenborg,JeffreyL.Hopkins,andRobertE.Stencel 647 AnneS.Young:ProfessorandVariableStarObserverExtraordinaire KatherineBracher 24 AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData(Posterabstract) MarcoCiocca,EthanE.Kilgore,andWestleyW.Williams 433 BVRIPhotometryofSN2011feinM101 MichaelW.RichmondandHoraceA.Smith 872 BritishAstronomicalAssociationVariableStarSection,1890–2011 JohnToone 154

Index, JAAVSO Volume 40, 2012 1053 CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 ACenturyofSupernovae PeterGarnavich 598 ClassicalCepheidsAfter228YearsofStudy DavidG.Turner 502 ClassicalandRecurrentNovae UlisseMunari 582 CollaborativeResearchEffortsforCitizenScientists(Posterabstract) BrianK.Kloppenborget al. 426 DataEvolutioninVSX:MakingaGoodThingBetter(Abstract) SebastianOtero 431 DataRelease3oftheAAVSOAll-SkyPhotometricSurvey(APASS)(Posterabstract) ArneA.Hendenet al. 430 dScorpii2011Periastron:VisualandDigitalPhotometricCampaign(Posterabstract) CostantinoSigismondiSapienza 419 DigitalArchiving:WherethePastLivesAgain KevinB.Paxson 360 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 TheEffectofOnlineSunspotDataonVisualSolarObservers KristineLarsen 374 eAurigae—anOverviewofthe2009–2011EclipseCampaignResults RobertE.Stencel 618 GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars—CXLyrae, NUAurigae,andVYCoronaeBorealis PierredePonthièreet al. 904 GSC4552-1643:aWUMaSystemWithCompleteEclipses DirkTerrellandJohnGross 941 HaEmissionExtractionUsingNarrowbandPhotometricFilters(Abstract) GaryWalker 432 HaSpectralMonitoringofeAurigae2009–2011Eclipse BenjaminMauclaireet al. 718 HighCadenceMeasurementofNeutralSodiumandPotassiumAbsorptionDuringthe 2009–2011EclipseofeAurigae RobinLeadbeateret al. 729 HighSchoolStudentsWatchingStarsEvolve(Abstract) JohnR.Percyet al. 416 HighSpeedUBVPhotometryofeAurigae’s2009–2011Eclipse(Posterabstract) AaronPriceet al. 418 HowAmateursCanContributetotheFieldofTransitingExoplanets BryceCroll 456 Hubble’sFamousPlateof1923:aStoryofPinkPolyethylene DavidR.Soderblom 321 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 IntensiveObservationsofCataclysmic,RRLyrae,andHighAmplitudedScuti(HADS) VariableStars Franz-JosefHambsch 289 TheInternationaleAurigaeCampaign2009PhotometryReport JeffreyL.Hopkins 633 IntroductiontotheJointAAS-AAVSOScientificPaperSessions MatthewR.Templeton 226 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239

Index, JAAVSO Volume 40, 20121054 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics JohnR.Percy 230 Miras LeeAnneWillsonandMassimoMarengo 516 NewLifeforOldData:DigitizationofDataPublishedintheHarvardAnnals(Abstract) MatthewR.Templetonet al. 429 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 ANoteontheVariabilityofV538Cassiopeiae GustavHolmberg 986 TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 AnOverviewoftheAAVSO’sInformationTechnologyInfrastructureFrom1967to1997 RichardC.S.Kinne 208 APracticalApproachtoTransformingMagnitudesontoaStandardPhotometricSystem DavidBoyd 990 ProfessionalAstronomersinServicetotheAAVSO(Posterabstract) MichaelSaladygaandElizabethO.Waagen 223 ProgressReportforAdaptingAPASSDataReleasesfortheCalibrationofHarvardPlates EdwardJ.Los 396 ThePulsationPeriodoftheHotHydrogen-DeficientStarMVSgr JohnR.PercyandRongFu 900 ThePulsationalBehavioroftheHighAmplitudedScutiStarRSGruis JaimeRubénGarcía 272 TheRASNZVariableStarSectionandVariableStarsSouth AlbertJonesandStanWalker 168 RecentMaximaof55ShortPeriodPulsatingStars GerardSamolyk 923 RecentMinimaof150EclipsingBinaryStars GerardSamolyk 975 RRLyraeStars:CosmicLighthousesWithaTwist KatrienKolenberg 481 RSSagittae:theSearchforEclipses JerryD.Horne 278 SecularVariationoftheModeAmplitude-RatiooftheDouble-ModeRRLyraeStar NSVS5222076,Part2 DavidA.HurdisandTomKrajci 268 SmallTelescopeInfraredPhotometryoftheeAurigaeEclipse ThomasP.Rutherford 704 StellarPhotometryWithDSLR:BenchmarkofTwoColorCorrectionTechniquesToward Johnson’sVJandTychoVT RogerPieri 834 AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 SymbioticStars UlisseMunari 572 ThingsWeDon’tUnderstandAboutRRLyraeStars HoraceA.Smith 327 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222 Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds DouglasL.Welch 492 TheVariableStarObservationsofFrankE.Seagrave(Abstract) GeraldP.Dyck 223

Index, JAAVSO Volume 40, 2012 1055 VariableStarObserversIHaveKnown CharlesE.Scovil 196 TheVariableStarsSouthEclipsingBinaryDatabase TomRichards 983 TheVariabilityofYoungStellarObjects WilliamHerbst 448 V-bandLightCurveAnalysisofeAurigaeDuringthe2009–2011Eclipse ThomasKarlsson 668 TheVisualEraoftheAAVSOEclipsingBinaryProgram DavidB.Williams,MarvinE.Baldwin,andGerardSamolyk 180 VSX:theNextGeneration(Abstract) ChristopherL.Watson 431 WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539 TheWorld’sStrangestSupernovaMayNotBeaSupernovaAtAll(Abstract) CarolineMoore 421 TheZCamPaignEarlyResults(Abstract) MikeSimonsen 241

AAVSO, JOURNAL OF AboutThis100thAnniversaryIssue JohnR.Percy 1 TheCitationofManuscriptsWhichHaveAppearedinJAAVSO ArloU.Landolt 1032 HighlightingeAurigaeandCitizenSky JohnR.Percy 609 IndextoVolume40 Anon. 1039 IntroductiontotheHistoryPaperSessions ThomasR.Williams 20 KeytotheCoverPhotographs Anon. 3 VariableStarObserversIHaveKnown CharlesE.Scovil 196 VariableStarsandConstantCommitments:theStellarCareerofDorritHoffleit KristineLarsen 44

AAVSO MEETINGS TheAAVSOWidow—orShouldWeSaySpouse? ThomasR.Williams 77 AboutThis100thAnniversaryIssue JohnR.Percy 1 AnneS.Young:ProfessorandVariableStarObserverExtraordinaire KatherineBracher 24 AnAppreciationofClintonB.FordandtheAAVSOofFiftyYearsAgo TonyHull 203 CentennialHighlightsinAstronomy OwenGingerich 438 GroupPhotographTakenatthe100thAnnualMeeting Anon. 9 GroupPhotographTakenatthe100thSpringMeeting Anon. 4 GuidingForcesandJanetA.Mattei ElizabethO.Waagen 65 HighlightingeAurigaeandCitizenSky JohnR.Percy 609

Index, JAAVSO Volume 40, 20121056 IntroductiontotheHistoryPaperSessions ThomasR.Williams 20 IntroductiontotheJointAAS-AAVSOScientificPaperSessions MatthewR.Templeton 226 Listof100thAnnualMeetingParticipants Anon. 11 Listof100thSpringMeetingParticipants Anon. 6 100thAnnualMeetingSchedule Anon. 15 100thSpringMeetingSchedule Anon. 8 ThePaperSessions—photographsofthepresenters Anon. 16 ReminiscencesontheCareerofMarthaStahrCarpenter:BetweenaRockand(Several)HardPlaces KristineLarsen 51 TheStarsBelongtoEveryone:AstronomerandScienceWriterHelenSawyerHogg(1905–1993) MariaJ.Cahill 31 VariableStarObserversIHaveKnown CharlesE.Scovil 196 VariableStarsandConstantCommitments:theStellarCareerofDorritHoffleit KristineLarsen 44 WalkingWithAAVSOGiants—aPersonalJourney(1960s) RogerS.KolmanandMikeSimonsen 189 The“WerkgroepVeranderlijkeSterren”ofBelgium PatrickWilset al. 164

AMPLITUDE ANALYSIS Miras LeeAnneWillsonandMassimoMarengo 516 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 SecularVariationoftheModeAmplitude-RatiooftheDouble-ModeRRLyraeStar NSVS5222076,Part2 DavidA.HurdisandTomKrajci 268

ARCHAEOASTRONOMY [See also ASTRONOMY, HISTORY OF] Flares,Fears,andForecasts:PublicMisconceptionsAbouttheSunspotCycle KristineLarsen 407

ASTEROIDS ContributionsbyCitizenScientiststoAstronomy(Abstract) ArneA.Henden 239 LightCurveofMinorPlanet1026Ingrid(Posterabstract) ShelbyDelos,GaryAhrendts,andTimothyBaker 423 TheRossVariableStarsRevisited.II WayneOsbornandO.FrankMills 929

ASTROMETRY FrankElmoreRossandHisVariableStarDiscoveries WayneOsborn 133 StatusoftheUSNOInfraredAstrometryProgram(Posterabstract) FrederickJohnVrbaet al. 434

ASTRONOMERS, AMATEUR; PROFESSIONAL-AMATEUR COLLABORATION AAVSOEstimatesandtheNatureofTypeCSemiregulars:ProgenitorsofTypeIISupernovae(Abstract) DavidG.Turneret al. 415

Index, JAAVSO Volume 40, 2012 1057 TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 TheAAVSO2011DemographicandBackgroundSurvey AaronPriceandKevinB.Paxson 1010 AboutThis100thAnniversaryIssue JohnR.Percy 1 TheAcquisitionofPhotometricData ArloU.Landolt 355 Algorithms+Observations=VStar DavidBenn 852 AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 AnAmateur-ProfessionalInternationalObservingCampaignfortheEPOXIMission: NewInsightsIntoComets(Abstract) KarenJ.Meech 422 AnAnalysisoftheLong-termPhotometricBehaviorofeAurigae BrianK.Kloppenborg,JeffreyL.Hopkins,andRobertE.Stencel 647 AnneS.Young:ProfessorandVariableStarObserverExtraordinaire KatherineBracher 24 AnAppreciationofClintonB.FordandtheAAVSOofFiftyYearsAgo TonyHull 203 AnArtist’sNoteonArtinScience NicoCamargo 867 BrightNewType-IaSupernovainthePinwheelGalaxy(M101):PhysicalPropertiesof SN2011feFromPhotometryandSpectroscopy(Posterabstract) SaiGouravajhalaet al. 419 BritishAstronomicalAssociationVariableStarSection,1890–2011 JohnToone 154 CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 CataclysmicVariablesintheBackyard(Abstract) JosephPatterson 240 ACenturyofSupernovae PeterGarnavich 598 TheCitizenSkyPlanetariumTrailer(Posterabstract) RebeccaTurner,AaronPrice,andRyanWyatt 428 ClassicalandRecurrentNovae UlisseMunari 582 CollaborativeResearchEffortsforCitizenScientists(Posterabstract) BrianK.Kloppenborget al. 426 ContributionsbyCitizenScientiststoAstronomy(Abstract) ArneA.Henden 239 DataEvolutioninVSX:MakingaGoodThingBetter(Abstract) SebastianOtero 431 ADemonstrationofAccurateWide-fieldV-bandPhotometryUsingaConsumer-gradeDSLRCamera BrianK.Kloppenborget al. 815 DigitalArchiving:WherethePastLivesAgain KevinB.Paxson 360 EclipseSpectropolarimetryoftheeAurigaeSystem KathleenM.Geiseet al. 767 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 eAurigae—anOverviewofthe2009–2011EclipseCampaignResults RobertE.Stencel 618 TheGEOSAssociationofVariableStarObservers(Abstract) Franz-JosefHambschet al. 177

Index, JAAVSO Volume 40, 20121058 GuidingForcesandJanetA.Mattei ElizabethO.Waagen 65 HaSpectralMonitoringofeAurigae2009–2011Eclipse BenjaminMauclaireet al. 718 HighCadenceMeasurementofNeutralSodiumandPotassiumAbsorptionDuringthe 2009–2011EclipseofeAurigae RobinLeadbeateret al. 729 HighSchoolStudentsWatchingStarsEvolve(Abstract) JohnR.Percyet al. 416 HighSpeedUBVPhotometryofeAurigae’s2009–2011Eclipse(Posterabstract) AaronPriceet al. 418 HighlightingeAurigaeandCitizenSky JohnR.Percy 609 HistoryofAmateurVariableStarObservationsinJapan(Posterabstract) SeiichiroKiyota 178 HowAmateursCanContributetotheFieldofTransitingExoplanets BryceCroll 456 Hubble’sFamousPlateof1923:aStoryofPinkPolyethylene DavidR.Soderblom 321 TheHuntfortheQuark-Nova;aCallforObservers(Abstract) DavidJ.Laneet al. 425 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 IntensiveObservationsofCataclysmic,RRLyrae,andHighAmplitudedScuti(HADS) VariableStars Franz-JosefHambsch 289 InterferometryandtheCepheidDistanceScale ThomasG.BarnesIII 256 TheInternationaleAurigaeCampaign2009PhotometryReport JeffreyL.Hopkins 633 InternationalObservingCampaign:PhotometryandSpectroscopyofPCygni ErnstPollmannandThiloBauer 894 IntroductiontoBAV(Abstract) Franz-JosefHambschandJoachimHübscher 177 IntroductiontotheHistoryPaperSessions ThomasR.Williams 20 IntroductiontotheJointAAS-AAVSOScientificPaperSessions MatthewR.Templeton 226 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics JohnR.Percy 230 ModelingtheDiskintheeAurigaeSystem:aBriefReviewWithProposedNumericalSolutions RichardL.PearsonIIIandRobertE.Stencel 802 NewLifeforOldData:DigitizationofDataPublishedintheHarvardAnnals(Abstract) MatthewR.Templetonet al. 429 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 PhotoelectricPhotometryofeAurigaeDuringthe2009–2011EclipseSeason FrankJ.Melillo 695

Index, JAAVSO Volume 40, 2012 1059 PlanetHuntingWithHATNetandHATSouth(Abstract) GasparBakos 241 PolarimetryofeAurigae,FromNovember2009toJanuary2012 GaryM.Cole 787 PreliminaryAnalysisofMOSTObservationsoftheTrapezium(Abstract) MatthewR.Templetonet al. 415 ProfessionalAstronomersinServicetotheAAVSO(Posterabstract) MichaelSaladygaandElizabethO.Waagen 223 ThePulsationPeriodoftheHotHydrogen-DeficientStarMVSgr JohnR.PercyandRongFu 900 TheRASNZPhotometrySection,IncorporatingtheAucklandPhotoelectricObservers’ Group(Posterabstract) StanWalker 177 TheRASNZVariableStarSectionandVariableStarsSouth AlbertJonesandStanWalker 168 ReminiscencesontheCareerofMarthaStahrCarpenter:BetweenaRockand(Several)HardPlaces KristineLarsen 51 ReportFromtheeAurigaeCampaigninGreece GrigorisMaraveliaset al. 679 RRLyraeStars:CosmicLighthousesWithaTwist KatrienKolenberg 481 SmallTelescopeInfraredPhotometryoftheeAurigaeEclipse ThomasP.Rutherford 704 SolarCycle24—WillItBeUnusuallyQuiet?(Abstract) RodneyHowe 435 SpectroscopicResultsFromBlueHillsObservatoryofthe2009–2011EclipseofeAurigae StanleyA.Gorodenski 743 StarWatchingPromotedbytheMinistryoftheEnvironment,Japan SeiichiSakuma 391 TheStarsBelongtoEveryone:AstronomerandScienceWriterHelenSawyerHogg(1905–1993) MariaJ.Cahill 31 StellarPhotometryWithDSLR:BenchmarkofTwoColorCorrectionTechniquesToward Johnson’sVJandTychoVT RogerPieri 834 AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 SymbioticStars UlisseMunari 572 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222 Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds DouglasL.Welch 492 UV-Blue(CCD)andHistoric(Photographic)SpectraofeAurigae—Summary R.ElizabethGriffinandRobertE.Stencel 714 TheVariabilityofYoungStellarObjects WilliamHerbst 448 TheVariableStarObservationsofFrankE.Seagrave(Abstract) GeraldP.Dyck 223 VariableStarObserversIHaveKnown CharlesE.Scovil 196 VariableStarsandConstantCommitments:theStellarCareerofDorritHoffleit KristineLarsen 44 TheVariableStarsSouthEclipsingBinaryDatabase TomRichards 983

Index, JAAVSO Volume 40, 20121060 V-bandLightCurveAnalysisofeAurigaeDuringthe2009–2011Eclipse ThomasKarlsson 668 TheVisualEraoftheAAVSOEclipsingBinaryProgram DavidB.Williams,MarvinE.Baldwin,andGerardSamolyk 180 WalkingWithAAVSOGiants—aPersonalJourney(1960s) RogerS.KolmanandMikeSimonsen 189 The“WerkgroepVeranderlijkeSterren”ofBelgium PatrickWilset al. 164 WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539 TheWorldScienceFestival(Abstract) JohnPazmino 428 TheWorld’sStrangestSupernovaMayNotBeaSupernovaAtAll(Abstract) CarolineMoore 421 TheZCamPaignEarlyResults(Abstract) MikeSimonsen 241

ASTRONOMY, HISTORY OF [See also ARCHAEOASTRONOMY; OBITUARIES] TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 TheAAVSOWidow—orShouldWeSaySpouse? ThomasR.Williams 77 AboutThis100thAnniversaryIssue JohnR.Percy 1 TheAcquisitionofPhotometricData ArloU.Landolt 355 AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 AnneS.Young:ProfessorandVariableStarObserverExtraordinaire KatherineBracher 24 Apollo14RoadTrip(Posterabstract) PaulValleli 223 AnAppreciationofClintonB.FordandtheAAVSOofFiftyYearsAgo TonyHull 203 BritishAstronomicalAssociationVariableStarSection,1890–2011 JohnToone 154 CentennialHighlightsinAstronomy OwenGingerich 438 ACenturyofSupernovae PeterGarnavich 598 ClassicalandRecurrentNovae UlisseMunari 582 TheDevelopmentofEarlyPulsationTheory,or,HowCepheidsAreLikeSteamEngines MatthewStanley 100 DigitalArchiving:WherethePastLivesAgain KevinB.Paxson 360 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 EclipsingBinariesThatDon’tEclipseAnymore:theStrangeCaseoftheOnce (andFuture?)EclipsingBinaryQXCassiopeiae(Abstract) EdwardF.Guinanet al. 417 Flares,Fears,andForecasts:PublicMisconceptionsAbouttheSunspotCycle KristineLarsen 407 FrankElmoreRossandHisVariableStarDiscoveries WayneOsborn 133 TheGEOSAssociationofVariableStarObservers(Abstract) Franz-JosefHambschet al. 177

Index, JAAVSO Volume 40, 2012 1061 GuidingForcesandJanetA.Mattei ElizabethO.Waagen 65 HistoryofAmateurVariableStarObservationsinJapan(Posterabstract) SeiichiroKiyota 178 TheHistoryofVariableStars:aFreshLook(Abstract) RobertAlanHatch 151 HowAmateursCanContributetotheFieldofTransitingExoplanets BryceCroll 456 Hubble’sFamousPlateof1923:aStoryofPinkPolyethylene DavidR.Soderblom 321 Illinois—WhereAstronomicalPhotometryGrewUp BarryB.BeamanandMichaelT.Svec 141 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 InterferometryandtheCepheidDistanceScale ThomasG.BarnesIII 256 IntroductiontoBAV(Abstract) Franz-JosefHambschandJoachimHübscher 177 IntroductiontotheHistoryPaperSessions ThomasR.Williams 20 IntroductiontotheJointAAS-AAVSOScientificPaperSessions MatthewR.Templeton 226 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 KingCharles’Star:AMultidisciplinaryApproachtoDatingtheSupernovaKnownas CassiopeiaA(Abstract) MartinLunn 150 TheLegacyofAnnieJumpCannon:DiscoveriesandCataloguesofVariableStars(Abstract) BarbaraL.Welther 92 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics JohnR.Percy 230 MargaretW.MayallintheAAVSOArchives(Abstract) MichaelSaladyga 92 Miras LeeAnneWillsonandMassimoMarengo 516 NewLifeforOldData:DigitizationofDataPublishedintheHarvardAnnals(Abstract) MatthewR.Templetonet al. 429 TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 AnOverviewoftheAAVSO’sInformationTechnologyInfrastructureFrom1967to1997 RichardC.S.Kinne 208 ProfessionalAstronomersinServicetotheAAVSO(Posterabstract) MichaelSaladygaandElizabethO.Waagen 223 TheRASNZPhotometrySection,IncorporatingtheAucklandPhotoelectricObservers’ Group(Posterabstract) StanWalker 177 TheRASNZVariableStarSectionandVariableStarsSouth AlbertJonesandStanWalker 168 ReminiscencesontheCareerofMarthaStahrCarpenter:BetweenaRockand(Several)HardPlaces KristineLarsen 51 TheRossVariableStarsRevisited.II WayneOsbornandO.FrankMills 929

Index, JAAVSO Volume 40, 20121062 StarWatchingPromotedbytheMinistryoftheEnvironment,Japan SeiichiSakuma 391 TheStarsBelongtoEveryone:AstronomerandScienceWriterHelenSawyerHogg(1905–1993) MariaJ.Cahill 31 StellarPulsationTheoryFromArthurStanleyEddingtontoToday(Abstract) StevenD.KawalerandCarlJ.Hansen 150 SymbioticStars UlisseMunari 572 ThingsWeDon’tUnderstandAboutRRLyraeStars HoraceA.Smith 327 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222 Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds DouglasL.Welch 492 TheVariableStarObservationsofFrankE.Seagrave(Abstract) GeraldP.Dyck 223 VariableStarObserversIHaveKnown CharlesE.Scovil 196 VariableStarsandConstantCommitments:theStellarCareerofDorritHoffleit KristineLarsen 44 TheVisualEraoftheAAVSOEclipsingBinaryProgram DavidB.Williams,MarvinE.Baldwin,andGerardSamolyk 180 WalkingWithAAVSOGiants—aPersonalJourney(1960s) RogerS.KolmanandMikeSimonsen 189 The“WerkgroepVeranderlijkeSterren”ofBelgium PatrickWilset al. 164 WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539

ASTRONOMY, WOMEN IN TheAAVSO2011DemographicandBackgroundSurvey AaronPriceandKevinB.Paxson 1010 TheAAVSOWidow—orShouldWeSaySpouse? ThomasR.Williams 77 AnneS.Young:ProfessorandVariableStarObserverExtraordinaire KatherineBracher 24 Apollo14RoadTrip(Posterabstract) PaulValleli 223 CentennialHighlightsinAstronomy OwenGingerich 438 GuidingForcesandJanetA.Mattei ElizabethO.Waagen 65 IntroductiontotheHistoryPaperSessions ThomasR.Williams 20 TheLegacyofAnnieJumpCannon:DiscoveriesandCataloguesofVariableStars(Abstract) BarbaraL.Welther 92 MargaretW.MayallintheAAVSOArchives(Abstract) MichaelSaladyga 92 AnOverviewoftheAAVSO’sInformationTechnologyInfrastructureFrom1967to1997 RichardC.S.Kinne 208 ProfessionalAstronomersinServicetotheAAVSO(Posterabstract) MichaelSaladygaandElizabethO.Waagen 223 ReminiscencesontheCareerofMarthaStahrCarpenter:BetweenaRockand(Several)HardPlaces KristineLarsen 51

Index, JAAVSO Volume 40, 2012 1063 TheStarsBelongtoEveryone:AstronomerandScienceWriterHelenSawyerHogg(1905–1993) MariaJ.Cahill 31 VariableStarsandConstantCommitments:theStellarCareerofDorritHoffleit KristineLarsen 44 WalkingWithAAVSOGiants—aPersonalJourney(1960s) RogerS.KolmanandMikeSimonsen 189

ATMOSPHERES, STELLAR ClassicalandRecurrentNovae UlisseMunari 582 ClassicalCepheidsAfter228YearsofStudy DavidG.Turner 502 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 Miras LeeAnneWillsonandMassimoMarengo 516 ProbingMiraAtmospheresUsingOpticalInterferometricTechniques(Abstract) SamRagland 265 Stars,Planets,andtheWeather:ifYouDon’tLikeItWaitFiveBillionYears(Abstract) JeremyJ.Drake 425 WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539

AWARDS VariableStarObserversIHaveKnown CharlesE.Scovil 196 VariableStarsandConstantCommitments:theStellarCareerofDorritHoffleit KristineLarsen 44

B STARS [See also VARIABLE STARS (GENERAL)] Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442

Be STARS [See also VARIABLE STARS (GENERAL)] Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 TheVariabilityofYoungStellarObjects WilliamHerbst 448

BINARY STARS BrightNewType-IaSupernovainthePinwheelGalaxy(M101):PhysicalPropertiesof SN2011feFromPhotometryandSpectroscopy(Posterabstract) SaiGouravajhalaet al. 419 ClassicalandRecurrentNovae UlisseMunari 582 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 StatusoftheUSNOInfraredAstrometryProgram(Posterabstract) FrederickJohnVrbaet al. 434 AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222

Index, JAAVSO Volume 40, 20121064 Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds DouglasL.Welch 492 WhatMassLossModelingTellsUsAboutPlanetaryNebulae(Abstract) LeeAnneWillsonandQianWang 424

BIOGRAPHY [See also ASTRONOMY, HISTORY OF] TheAAVSOWidow—orShouldWeSaySpouse? ThomasR.Williams 77 AnneS.Young:ProfessorandVariableStarObserverExtraordinaire KatherineBracher 24 AnAppreciationofClintonB.FordandtheAAVSOofFiftyYearsAgo TonyHull 203 CentennialHighlightsinAstronomy OwenGingerich 438 FrankElmoreRossandHisVariableStarDiscoveries WayneOsborn 133 GuidingForcesandJanetA.Mattei ElizabethO.Waagen 65 HistoryofAmateurVariableStarObservationsinJapan(Posterabstract) SeiichiroKiyota 178 Illinois—WhereAstronomicalPhotometryGrewUp BarryB.BeamanandMichaelT.Svec 141 IntroductiontotheHistoryPaperSessions ThomasR.Williams 20 JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 TheLegacyofAnnieJumpCannon:DiscoveriesandCataloguesofVariableStars(Abstract) BarbaraL.Welther 92 MargaretW.MayallintheAAVSOArchives(Abstract) MichaelSaladyga 92 ProfessionalAstronomersinServicetotheAAVSO(Posterabstract) MichaelSaladygaandElizabethO.Waagen 223 TheRASNZVariableStarSectionandVariableStarsSouth AlbertJonesandStanWalker 168 ReminiscencesontheCareerofMarthaStahrCarpenter:BetweenaRockand(Several)HardPlaces KristineLarsen 51 TheStarsBelongtoEveryone:AstronomerandScienceWriterHelenSawyerHogg(1905–1993) MariaJ.Cahill 31 StellarPulsationTheoryFromArthurStanleyEddingtontoToday(Abstract) StevenD.KawalerandCarlJ.Hansen 150 VariableStarObserversIHaveKnown CharlesE.Scovil 196 VariableStarsandConstantCommitments:theStellarCareerofDorritHoffleit KristineLarsen 44 WalkingWithAAVSOGiants—aPersonalJourney(1960s) RogerS.KolmanandMikeSimonsen 189

BLAZARS [See also VARIABLE STARS (GENERAL)] ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222

CATACLYSMIC VARIABLES [See also VARIABLE STARS (GENERAL)] AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348

Index, JAAVSO Volume 40, 2012 1065 CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 CataclysmicVariablesintheBackyard(Abstract) JosephPatterson 240 ClassicalandRecurrentNovae UlisseMunari 582 GuidingForcesandJanetA.Mattei ElizabethO.Waagen 65 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 IntensiveObservationsofCataclysmic,RRLyrae,andHighAmplitudedScuti(HADS) VariableStars Franz-JosefHambsch 289 IntroductiontotheJointAAS-AAVSOScientificPaperSessions MatthewR.Templeton 226 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 ROAD(RemoteObservatoryAtacamaDesert):IntensiveObservationsofVariableStars Franz-JosefHambsch 1003 AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 TheZCamPaignEarlyResults(Abstract) MikeSimonsen 241

CATALOGUES, DATABASES, SURVEYS TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 AAVSOnet:theRoboticTelescopeNetwork(Posterabstract) MikeSimonsen 432 TheAcquisitionofPhotometricData ArloU.Landolt 355 Algorithms+Observations=VStar DavidBenn 852 AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 AnAnalysisoftheLong-termPhotometricBehaviorofeAurigae BrianK.Kloppenborg,JeffreyL.Hopkins,andRobertE.Stencel 647 AnneS.Young:ProfessorandVariableStarObserverExtraordinaire KatherineBracher 24 BritishAstronomicalAssociationVariableStarSection,1890–2011 JohnToone 154 BVRIPhotometryofSN2011feinM101 MichaelW.RichmondandHoraceA.Smith 872 CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 ACenturyofSupernovae PeterGarnavich 598 ClassicalandRecurrentNovae UlisseMunari 582 CollaborativeResearchEffortsforCitizenScientists(Posterabstract) BrianK.Kloppenborget al. 426 DataEvolutioninVSX:MakingaGoodThingBetter(Abstract) SebastianOtero 431 DataRelease3oftheAAVSOAll-SkyPhotometricSurvey(APASS)(Posterabstract) ArneA.Hendenet al. 430

Index, JAAVSO Volume 40, 20121066 ADemonstrationofAccurateWide-fieldV-bandPhotometryUsingaConsumer-gradeDSLRCamera BrianK.Kloppenborget al. 815 DigitalArchiving:WherethePastLivesAgain KevinB.Paxson 360 EclipseSpectropolarimetryoftheeAurigaeSystem KathleenM.Geiseet al. 767 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 EnhancingtheEducationalAstronomicalExperienceofNon-ScienceMajorsWiththe UseofaniPadandTelescope(Abstract) RobertM.GillandMichaelJ.Burin 1037 eAurigae—anOverviewofthe2009–2011EclipseCampaignResults RobertE.Stencel 618 FrankElmoreRossandHisVariableStarDiscoveries WayneOsborn 133 TheGEOSAssociationofVariableStarObservers(Abstract) Franz-JosefHambschet al. 177 GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis PierredePonthièreet al. 904 GSC4552-1643:aWUMaSystemWithCompleteEclipses DirkTerrellandJohnGross 941 HaSpectralMonitoringofeAurigae2009–2011Eclipse BenjaminMauclaireet al. 718 HighCadenceMeasurementofNeutralSodiumandPotassiumAbsorptionDuringthe 2009–2011EclipseofeAurigae RobinLeadbeateret al. 729 HighSchoolStudentsWatchingStarsEvolve(Abstract) JohnR.Percyet al. 416 HowAmateursCanContributetotheFieldofTransitingExoplanets BryceCroll 456 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 IntensiveObservationsofCataclysmic,RRLyrae,andHighAmplitudedScuti(HADS) VariableStars Franz-JosefHambsch 289 InterferometryandtheCepheidDistanceScale ThomasG.BarnesIII 256 TheInternationaleAurigaeCampaign2009PhotometryReport JeffreyL.Hopkins 633 InternationalObservingCampaign:PhotometryandSpectroscopyofPCygni ErnstPollmannandThiloBauer 894 IntroductiontotheJointAAS-AAVSOScientificPaperSessions MatthewR.Templeton 226 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 IsMPGeminorumanEclipsingBinaryWithaVeryLongPeriod? DietmarBöhme 973 JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 MargaretW.MayallintheAAVSOArchives(Abstract) MichaelSaladyga 92 MembershipofthePlanetaryNebulaAbell8intheOpenClusterBica6andImplicationsfor thePNDistanceScale(Posterabstract) DavidG.Turneret al. 423 Miras LeeAnneWillsonandMassimoMarengo 516

Index, JAAVSO Volume 40, 2012 1067 NewLifeforOldData:DigitizationofDataPublishedintheHarvardAnnals(Abstract) MatthewR.Templetonet al. 429 NewLightCurveforthe1909OutburstofRTSerpentis GrantLuberdaandWayneOsborn 887 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 ANoteontheVariabilityofV538Cassiopeiae GustavHolmberg 986 TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 AnOverviewoftheAAVSO’sInformationTechnologyInfrastructureFrom1967to1997 RichardC.S.Kinne 208 PlanetHuntingWithHATNetandHATSouth(Abstract) GasparBakos 241 PolarimetryofeAurigae,FromNovember2009toJanuary2012 GaryM.Cole 787 APracticalApproachtoTransformingMagnitudesontoaStandardPhotometricSystem DavidBoyd 990 PreliminaryAnalysisofMOSTObservationsoftheTrapezium(Abstract) MatthewR.Templetonet al. 415 ProgressReportforAdaptingAPASSDataReleasesfortheCalibrationofHarvardPlates EdwardJ.Los 396 ThePulsationalBehavioroftheHighAmplitudedScutiStarRSGruis JaimeRubénGarcía 272 TheRASNZVariableStarSectionandVariableStarsSouth AlbertJonesandStanWalker 168 RecentMinimaof150EclipsingBinaryStars GerardSamolyk 975 ReminiscencesontheCareerofMarthaStahrCarpenter:BetweenaRockand(Several)HardPlaces KristineLarsen 51 TheRossVariableStarsRevisited.II WayneOsbornandO.FrankMills 929 RRLyraeStars:CosmicLighthousesWithaTwist KatrienKolenberg 481 RSSagittae:theSearchforEclipses JerryD.Horne 278 SecularVariationoftheModeAmplitude-RatiooftheDouble-ModeRRLyraeStar NSVS5222076,Part2 DavidA.HurdisandTomKrajci 268 StarWatchingPromotedbytheMinistryoftheEnvironment,Japan SeiichiSakuma 391 TheStarsBelongtoEveryone:AstronomerandScienceWriterHelenSawyerHogg(1905–1993) MariaJ.Cahill 31 StatusoftheUSNOInfraredAstrometryProgram(Posterabstract) FrederickJohnVrbaet al. 434 StellarPhotometryWithDSLR:BenchmarkofTwoColorCorrectionTechniquesToward Johnson’sVJandTychoVT RogerPieri 834 AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 SymbioticStars UlisseMunari 572 ThingsWeDon’tUnderstandAboutRRLyraeStars HoraceA.Smith 327 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222

Index, JAAVSO Volume 40, 20121068 Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds DouglasL.Welch 492 TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 UV-Blue(CCD)andHistoric(Photographic)SpectraofeAurigae—Summary R.ElizabethGriffinandRobertE.Stencel 714 VariabilityTypeDeterminationandHighPrecisionEphemerisforNSVS7606408 RiccardoFurgoni 955 VariableStarsandConstantCommitments:theStellarCareerofDorritHoffleit KristineLarsen 44 TheVariableStarsSouthEclipsingBinaryDatabase TomRichards 983 V-bandLightCurveAnalysisofeAurigaeDuringthe2009–2011Eclipse ThomasKarlsson 668 TheVisualEraoftheAAVSOEclipsingBinaryProgram DavidB.Williams,MarvinE.Baldwin,andGerardSamolyk 180 VSX:theNextGeneration(Abstract) ChristopherL.Watson 431 The“WerkgroepVeranderlijkeSterren”ofBelgium PatrickWilset al. 164 WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539 TheZCamPaignEarlyResults(Abstract) MikeSimonsen 241

CEPHEID VARIABLES [See also VARIABLE STARS (GENERAL)] Algorithms+Observations=VStar DavidBenn 852 ClassicalCepheidsAfter228YearsofStudy DavidG.Turner 502 TheDevelopmentofEarlyPulsationTheory,or,HowCepheidsAreLikeSteamEngines MatthewStanley 100 Hubble’sFamousPlateof1923:aStoryofPinkPolyethylene DavidR.Soderblom 321 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 InterferometryandtheCepheidDistanceScale ThomasG.BarnesIII 256 IntroductiontotheJointAAS-AAVSOScientificPaperSessions MatthewR.Templeton 226 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics JohnR.Percy 230 Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds DouglasL.Welch 492

CHARGE-COUPLED DEVICES (CCDs) [See also PHOTOMETRY, CCD] TheAcquisitionofPhotometricData ArloU.Landolt 355

Index, JAAVSO Volume 40, 2012 1069CHARTS, VARIABLE STAR TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 BritishAstronomicalAssociationVariableStarSection,1890–2011 JohnToone 154 GuidingForcesandJanetA.Mattei ElizabethO.Waagen 65 IsMPGeminorumanEclipsingBinaryWithaVeryLongPeriod? DietmarBöhme 973 AnOverviewoftheAAVSO’sInformationTechnologyInfrastructureFrom1967to1997 RichardC.S.Kinne 208 TheRASNZVariableStarSectionandVariableStarsSouth AlbertJonesandStanWalker 168 VariableStarObserversIHaveKnown CharlesE.Scovil 196 TheVisualEraoftheAAVSOEclipsingBinaryProgram DavidB.Williams,MarvinE.Baldwin,andGerardSamolyk 180

CHARTS; COMPARISON STAR SEQUENCES TheAcquisitionofPhotometricData ArloU.Landolt 355 BritishAstronomicalAssociationVariableStarSection,1890–2011 JohnToone 154 BVRIPhotometryofSN2011feinM101 MichaelW.RichmondandHoraceA.Smith 872 APracticalApproachtoTransformingMagnitudesontoaStandardPhotometricSystem DavidBoyd 990 ProgressReportforAdaptingAPASSDataReleasesfortheCalibrationofHarvardPlates EdwardJ.Los 396 TheRASNZVariableStarSectionandVariableStarsSouth AlbertJonesandStanWalker 168 SymbioticStars UlisseMunari 572 VariableStarObserversIHaveKnown CharlesE.Scovil 196 TheVisualEraoftheAAVSOEclipsingBinaryProgram DavidB.Williams,MarvinE.Baldwin,andGerardSamolyk 180

CLUSTERS, GLOBULAR EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 RRLyraeStars:CosmicLighthousesWithaTwist KatrienKolenberg 481 SecularVariationoftheModeAmplitude-RatiooftheDouble-ModeRRLyraeStar NSVS5222076,Part2 DavidA.HurdisandTomKrajci 268 TheStarsBelongtoEveryone:AstronomerandScienceWriterHelenSawyerHogg(1905–1993) MariaJ.Cahill 31 ThingsWeDon’tUnderstandAboutRRLyraeStars HoraceA.Smith 327 Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds DouglasL.Welch 492

CLUSTERS, OPEN ClassicalCepheidsAfter228YearsofStudy DavidG.Turner 502

Index, JAAVSO Volume 40, 20121070 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 EclipsingBinariesThatDon’tEclipseAnymore:theStrangeCaseoftheOnce (andFuture?)EclipsingBinaryQXCassiopeiae(Abstract) EdwardF.Guinanet al. 417 InterferometryandtheCepheidDistanceScale ThomasG.BarnesIII 256 MembershipofthePlanetaryNebulaAbell8intheOpenClusterBica6andImplicationsfor thePNDistanceScale(Posterabstract) DavidG.Turneret al. 423 ANoteontheVariabilityofV538Cassiopeiae GustavHolmberg 986 ReminiscencesontheCareerofMarthaStahrCarpenter:BetweenaRockand(Several)HardPlaces KristineLarsen 51

COMETS AnAmateur-ProfessionalInternationalObservingCampaignfortheEPOXIMission: NewInsightsIntoComets(Abstract) KarenJ.Meech 422 FrankElmoreRossandHisVariableStarDiscoveries WayneOsborn 133 ReminiscencesontheCareerofMarthaStahrCarpenter:BetweenaRockand(Several)HardPlaces KristineLarsen 51

COMPUTERS; COMPUTER PROGRAMS; INTERNET, WORLD WIDE WEB TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 AAVSOnet:theRoboticTelescopeNetwork(Posterabstract) MikeSimonsen 432 Algorithms+Observations=VStar DavidBenn 852 ContributionsbyCitizenScientiststoAstronomy(Abstract) ArneA.Henden 239 DataEvolutioninVSX:MakingaGoodThingBetter(Abstract) SebastianOtero 431 ADemonstrationofAccurateWide-fieldV-bandPhotometryUsingaConsumer-gradeDSLRCamera BrianK.Kloppenborget al. 815 DigitalArchiving:WherethePastLivesAgain KevinB.Paxson 360 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 EnhancingtheEducationalAstronomicalExperienceofNon-ScienceMajorsWiththe UseofaniPadandTelescope(Abstract) RobertM.GillandMichaelJ.Burin 1037 GSC4552-1643:aWUMaSystemWithCompleteEclipses DirkTerrellandJohnGross 941 HaEmissionExtractionUsingNarrowbandPhotometricFilters(Abstract) GaryWalker 432 HowAmateursCanContributetotheFieldofTransitingExoplanets BryceCroll 456 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 IsMPGeminorumanEclipsingBinaryWithaVeryLongPeriod? DietmarBöhme 973 Miras LeeAnneWillsonandMassimoMarengo 516

Index, JAAVSO Volume 40, 2012 1071 ModelingtheDiskintheeAurigaeSystem:aBriefReviewWithProposedNumericalSolutions RichardL.PearsonIIIandRobertE.Stencel 802 NewLifeforOldData:DigitizationofDataPublishedintheHarvardAnnals(Abstract) MatthewR.Templetonet al. 429 AnOverviewoftheAAVSO’sInformationTechnologyInfrastructureFrom1967to1997 RichardC.S.Kinne 208 StatusoftheUSNOInfraredAstrometryProgram(Posterabstract) FrederickJohnVrbaet al. 434 StellarPhotometryWithDSLR:BenchmarkofTwoColorCorrectionTechniquesToward Johnson’sVJandTychoVT RogerPieri 834 TheVisualEraoftheAAVSOEclipsingBinaryProgram DavidB.Williams,MarvinE.Baldwin,andGerardSamolyk 180 VSX:theNextGeneration(Abstract) ChristopherL.Watson 431

CONSTANT/NON-VARIABLE STARS ANoteontheVariabilityofV538Cassiopeiae GustavHolmberg 986

COORDINATED OBSERVATIONS [MULTI-SITE, MULTI-WAVELENGTH OBSERVATIONS] TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 AAVSOnet:theRoboticTelescopeNetwork(Posterabstract) MikeSimonsen 432 AnAmateur-ProfessionalInternationalObservingCampaignfortheEPOXIMission: NewInsightsIntoComets(Abstract) KarenJ.Meech 422 CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 CataclysmicVariablesintheBackyard(Abstract) JosephPatterson 240 ADemonstrationofAccurateWide-fieldV-bandPhotometryUsingaConsumer-gradeDSLRCamera BrianK.Kloppenborget al. 815 eAurigae—anOverviewofthe2009–2011EclipseCampaignResults RobertE.Stencel 618 HaSpectralMonitoringofeAurigae2009–2011Eclipse BenjaminMauclaireet al. 718 TheHuntfortheQuark-Nova;aCallforObservers(Abstract) DavidJ.Laneet al. 425 TheInternationaleAurigaeCampaign2009PhotometryReport JeffreyL.Hopkins 633 InternationalObservingCampaign:PhotometryandSpectroscopyofPCygni ErnstPollmannandThiloBauer 894 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 PlanetHuntingWithHATNetandHATSouth(Abstract) GasparBakos 241 ROAD(RemoteObservatoryAtacamaDesert):IntensiveObservationsofVariableStars Franz-JosefHambsch 1003 SmallTelescopeInfraredPhotometryoftheeAurigaeEclipse ThomasP.Rutherford 704 Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94

Index, JAAVSO Volume 40, 20121072 TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 V-bandLightCurveAnalysisofeAurigaeDuringthe2009–2011Eclipse ThomasKarlsson 668 VSXJ071108.7+695227:aNewlyDiscoveredShort-periodEclipsingBinary MarioDamasso et al. 945

DARK ADAPTATION AdverseHealthEffectsofNighttimeLighting MarioMotta 380

DATA MANAGEMENT [See also AAVSO; COMPUTERS] AAVSOnet:theRoboticTelescopeNetwork(Posterabstract) MikeSimonsen 432 Algorithms+Observations=VStar DavidBenn 852 DataEvolutioninVSX:MakingaGoodThingBetter(Abstract) SebastianOtero 431 DigitalArchiving:WherethePastLivesAgain KevinB.Paxson 360 NewLifeforOldData:DigitizationofDataPublishedintheHarvardAnnals(Abstract) MatthewR.Templetonet al. 429 AnOverviewoftheAAVSO’sInformationTechnologyInfrastructureFrom1967to1997 RichardC.S.Kinne 208 SolarCycle24—WillItBeUnusuallyQuiet?(Abstract) RodneyHowe 435 TheVisualEraoftheAAVSOEclipsingBinaryProgram DavidB.Williams,MarvinE.Baldwin,andGerardSamolyk 180 VSX:theNextGeneration(Abstract) ChristopherL.Watson 431

DATA MINING AAVSOnet:theRoboticTelescopeNetwork(Posterabstract) MikeSimonsen 432 Algorithms+Observations=VStar DavidBenn 852 CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 DataRelease3oftheAAVSOAll-SkyPhotometricSurvey(APASS)(Posterabstract) ArneA.Hendenet al. 430 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 HowAmateursCanContributetotheFieldofTransitingExoplanets BryceCroll 456 Miras LeeAnneWillsonandMassimoMarengo 516 NewLifeforOldData:DigitizationofDataPublishedintheHarvardAnnals(Abstract) MatthewR.Templetonet al. 429 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds DouglasL.Welch 492 TheVariableStarsSouthEclipsingBinaryDatabase TomRichards 983 The“WerkgroepVeranderlijkeSterren”ofBelgium PatrickWilset al. 164

Index, JAAVSO Volume 40, 2012 1073DATABASES [See CATALOGUES]

DELTA SCUTI STARS [See also VARIABLE STARS (GENERAL)] AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData(Posterabstract) MarcoCiocca,EthanE.Kilgore,andWestleyW.Williams 433 ClassicalCepheidsAfter228YearsofStudy DavidG.Turner 502 IntensiveObservationsofCataclysmic,RRLyrae,andHighAmplitudedScuti(HADS) VariableStars Franz-JosefHambsch 289 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 ThePulsationalBehavioroftheHighAmplitudedScutiStarRSGruis JaimeRubénGarcía 272

DOUBLE STARS [See also VARIABLE STARS (GENERAL)] dScorpii2011Periastron:VisualandDigitalPhotometricCampaign(Posterabstract) CostantinoSigismondiSapienza 419 MembershipofthePlanetaryNebulaAbell8intheOpenClusterBica6andImplicationsfor thePNDistanceScale(Posterabstract) DavidG.Turneret al. 423

DWARF NOVAE [See also CATACLYSMIC VARIABLES] CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 FrankElmoreRossandHisVariableStarDiscoveries WayneOsborn 133

DWARF STARS EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 MembershipofthePlanetaryNebulaAbell8intheOpenClusterBica6andImplicationsfor thePNDistanceScale(Posterabstract) DavidG.Turneret al. 423 StatusoftheUSNOInfraredAstrometryProgram(Posterabstract) FrederickJohnVrbaet al. 434

ECLIPSING BINARIES [See also VARIABLE STARS (GENERAL)] Algorithms+Observations=VStar DavidBenn 852 AnAnalysisoftheLong-termPhotometricBehaviorofeAurigae BrianK.Kloppenborg,JeffreyL.Hopkins,andRobertE.Stencel 647 TheCitizenSkyPlanetariumTrailer(Posterabstract) RebeccaTurner,AaronPrice,andRyanWyatt 428 EclipseSpectropolarimetryoftheeAurigaeSystem KathleenM.Geiseet al. 767 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 EclipsingBinariesThatDon’tEclipseAnymore:theStrangeCaseoftheOnce (andFuture?)EclipsingBinaryQXCassiopeiae(Abstract) EdwardF.Guinanet al. 417 eAurigae—anOverviewofthe2009–2011EclipseCampaignResults RobertE.Stencel 618 GSC4552-1643:aWUMaSystemWithCompleteEclipses DirkTerrellandJohnGross 941 HaSpectralMonitoringofeAurigae2009–2011Eclipse BenjaminMauclaireet al. 718

Index, JAAVSO Volume 40, 20121074 HighCadenceMeasurementofNeutralSodiumandPotassiumAbsorptionDuringthe 2009–2011EclipseofeAurigae RobinLeadbeateret al. 729 HighSpeedUBVPhotometryofeAurigae’s2009–2011Eclipse(Posterabstract) AaronPriceet al. 418 HighlightingeAurigaeandCitizenSky JohnR.Percy 609 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 TheInternationaleAurigaeCampaign2009PhotometryReport JeffreyL.Hopkins 633 IsMPGeminorumanEclipsingBinaryWithaVeryLongPeriod? DietmarBöhme 973 JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics JohnR.Percy 230 ModelingtheDiskintheeAurigaeSystem:aBriefReviewWithProposedNumericalSolutions RichardL.PearsonIIIandRobertE.Stencel 802 TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 PhotoelectricPhotometryofeAurigaeDuringthe2009–2011EclipseSeason FrankJ.Melillo 695 PolarimetryofeAurigae,FromNovember2009toJanuary2012 GaryM.Cole 787 RecentMinimaof150EclipsingBinaryStars GerardSamolyk 975 ReportFromtheeAurigaeCampaigninGreece GrigorisMaraveliaset al. 679 RSSagittae:theSearchforEclipses JerryD.Horne 278 SmallTelescopeInfraredPhotometryoftheeAurigaeEclipse ThomasP.Rutherford 704 SpectroscopicResultsFromBlueHillsObservatoryofthe2009–2011EclipseofeAurigae StanleyA.Gorodenski 743 Spots,Eclipses,andPulsation:theInterplayofPhotometryandOpticalInterferometric Imaging(Abstract) BrianK.Kloppenborg 266 StellarPhotometryWithDSLR:BenchmarkofTwoColorCorrectionTechniquesToward Johnson’sVJandTychoVT RogerPieri 834 UV-Blue(CCD)andHistoric(Photographic)SpectraofeAurigae—Summary R.ElizabethGriffinandRobertE.Stencel 714 V-bandLightCurveAnalysisofeAurigaeDuringthe2009–2011Eclipse ThomasKarlsson 668 VariabilityTypeDeterminationandHighPrecisionEphemerisforNSVS7606408 RiccardoFurgoni 955 TheVariableStarsSouthEclipsingBinaryDatabase TomRichards 983 TheVisualEraoftheAAVSOEclipsingBinaryProgram DavidB.Williams,MarvinE.Baldwin,andGerardSamolyk 180 VSXJ071108.7+695227:aNewlyDiscoveredShort-periodEclipsingBinary MarioDamasso et al. 945

Index, JAAVSO Volume 40, 2012 1075EDUCATION TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 TheAAVSO2011DemographicandBackgroundSurvey AaronPriceandKevinB.Paxson 1010 AnneS.Young:ProfessorandVariableStarObserverExtraordinaire KatherineBracher 24 AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData(Posterabstract) MarcoCiocca,EthanE.Kilgore,andWestleyW.Williams 433 TheCitizenSkyPlanetariumTrailer(Posterabstract) RebeccaTurner,AaronPrice,andRyanWyatt 428 CollaborativeResearchEffortsforCitizenScientists(Posterabstract) BrianK.Kloppenborget al. 426 TheEffectofOnlineSunspotDataonVisualSolarObservers KristineLarsen 374 EnhancingtheEducationalAstronomicalExperienceofNon-ScienceMajorsWiththe UseofaniPadandTelescope(Abstract) RobertM.GillandMichaelJ.Burin 1037 ExploringtheBreadthandSourcesofVariableStarAstronomers’AstronomyKnowledge: FirstSteps(Abstract) StephanieJ.Slater 427 Flares,Fears,andForecasts:PublicMisconceptionsAbouttheSunspotCycle KristineLarsen 407 GuidingForcesandJanetA.Mattei ElizabethO.Waagen 65 Illinois—WhereAstronomicalPhotometryGrewUp BarryB.BeamanandMichaelT.Svec 141 JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 RaschAnalysisofScientificLiteracyinanAstronomicalCitizenScienceProject(Posterabstract) AaronPrice 427 ReminiscencesontheCareerofMarthaStahrCarpenter:BetweenaRockand(Several)HardPlaces KristineLarsen 51 TheStarsBelongtoEveryone:AstronomerandScienceWriterHelenSawyerHogg(1905–1993) MariaJ.Cahill 31 VariableStarsandConstantCommitments:theStellarCareerofDorritHoffleit KristineLarsen 44

EDUCATION, VARIABLE STARS IN TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 TheAAVSO2011DemographicandBackgroundSurvey AaronPriceandKevinB.Paxson 1010 AnneS.Young:ProfessorandVariableStarObserverExtraordinaire KatherineBracher 24 AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData(Posterabstract) MarcoCiocca,EthanE.Kilgore,andWestleyW.Williams 433 TheCitizenSkyPlanetariumTrailer(Posterabstract) RebeccaTurner,AaronPrice,andRyanWyatt 428 CollaborativeResearchEffortsforCitizenScientists(Posterabstract) BrianK.Kloppenborget al. 426 TheEffectofOnlineSunspotDataonVisualSolarObservers KristineLarsen 374

Index, JAAVSO Volume 40, 20121076 EnhancingtheEducationalAstronomicalExperienceofNon-ScienceMajorsWiththe UseofaniPadandTelescope(Abstract) RobertM.GillandMichaelJ.Burin 1037 ExploringtheBreadthandSourcesofVariableStarAstronomers’AstronomyKnowledge: FirstSteps(Abstract) StephanieJ.Slater 427 Flares,Fears,andForecasts:PublicMisconceptionsAbouttheSunspotCycle KristineLarsen 407 GuidingForcesandJanetA.Mattei ElizabethO.Waagen 65 HighSchoolStudentsWatchingStarsEvolve(Abstract) JohnR.Percyet al. 416 HighlightingeAurigaeandCitizenSky JohnR.Percy 609 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics JohnR.Percy 230 Miras LeeAnneWillsonandMassimoMarengo 516 TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 ThePulsationPeriodoftheHotHydrogen-DeficientStarMVSgr JohnR.PercyandRongFu 900 RaschAnalysisofScientificLiteracyinanAstronomicalCitizenScienceProject(Posterabstract) AaronPrice 427 TheStarsBelongtoEveryone:AstronomerandScienceWriterHelenSawyerHogg(1905–1993) MariaJ.Cahill 31 VariableStarsandConstantCommitments:theStellarCareerofDorritHoffleit KristineLarsen 44 TheWorldScienceFestival(Abstract) JohnPazmino 428

ELECTRONIC COMMUNICATION; [See NETWORKS, COMMUNICATION; ELECTRONIC COMMUNICATION]

EQUIPMENT [See INSTRUMENTATION]

ERUPTIVE VARIABLES [See also VARIABLE STARS (GENERAL)] ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222

EVOLUTION, STELLAR AAVSOEstimatesandtheNatureofTypeCSemiregulars:ProgenitorsofTypeIISupernovae(Abstract) DavidG.Turneret al. 415 BrightNewType-IaSupernovainthePinwheelGalaxy(M101):PhysicalPropertiesof SN2011feFromPhotometryandSpectroscopy(Posterabstract) SaiGouravajhalaet al. 419 CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563

Index, JAAVSO Volume 40, 2012 1077 CentennialHighlightsinAstronomy OwenGingerich 438 ACenturyofSupernovae PeterGarnavich 598 ClassicalandRecurrentNovae UlisseMunari 582 ClassicalCepheidsAfter228YearsofStudy DavidG.Turner 502 TheDevelopmentofEarlyPulsationTheory,or,HowCepheidsAreLikeSteamEngines MatthewStanley 100 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 HighSchoolStudentsWatchingStarsEvolve(Abstract) JohnR.Percyet al. 416 TheHuntfortheQuark-Nova;aCallforObservers(Abstract) DavidJ.Laneet al. 425 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics JohnR.Percy 230 Miras LeeAnneWillsonandMassimoMarengo 516 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 RRLyraeStars:CosmicLighthousesWithaTwist KatrienKolenberg 481 StellarPulsationTheoryFromArthurStanleyEddingtontoToday(Abstract) StevenD.KawalerandCarlJ.Hansen 150 ThingsWeDon’tUnderstandAboutRRLyraeStars HoraceA.Smith 327 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222 Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds DouglasL.Welch 492 TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 TheVariabilityofYoungStellarObjects WilliamHerbst 448 VariableStarsandtheAsymptoticGiantBranch:StellarPulsations,DustProduction,andMassLoss AngelaK.Speck 244 WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539 TheWorld’sStrangestSupernovaMayNotBeaSupernovaAtAll(Abstract) CarolineMoore 421

EXOPLANETS [See PLANETS, EXTRASOLAR]

EXTRAGALACTIC ClassicalandRecurrentNovae UlisseMunari 582

Index, JAAVSO Volume 40, 20121078 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222 WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539 TheWorld’sStrangestSupernovaMayNotBeaSupernovaAtAll(Abstract) CarolineMoore 421

FLARE STARS [See also VARIABLE STARS (GENERAL)] Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442

FU ORIONIS VARIABLES TheVariabilityofYoungStellarObjects WilliamHerbst 448

GALAXIES BVRIPhotometryofSN2011feinM101 MichaelW.RichmondandHoraceA.Smith 872 CentennialHighlightsinAstronomy OwenGingerich 438 ClassicalCepheidsAfter228YearsofStudy DavidG.Turner 502 Hubble’sFamousPlateof1923:aStoryofPinkPolyethylene DavidR.Soderblom 321 JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 ReminiscencesontheCareerofMarthaStahrCarpenter:BetweenaRockand(Several)HardPlaces KristineLarsen 51 TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334

GAMMA CASSIOPEIAE VARIABLES [See also VARIABLE STARS (GENERAL)] Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442

GAMMA-RAY BURSTS; GAMMA-RAY EMISSION ACenturyofSupernovae PeterGarnavich 598

GIANTS, NON-MIRA TYPE dScorpii2011Periastron:VisualandDigitalPhotometricCampaign(Posterabstract) CostantinoSigismondiSapienza 419 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 SymbioticStars UlisseMunari 572

GIANTS, RED TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528

Index, JAAVSO Volume 40, 2012 1079HIPPARCOS DATABASE AnAnalysisoftheLong-termPhotometricBehaviorofeAurigae BrianK.Kloppenborg,JeffreyL.Hopkins,andRobertE.Stencel 647 ADemonstrationofAccurateWide-fieldV-bandPhotometryUsingaConsumer-gradeDSLRCamera BrianK.Kloppenborget al. 815 ModelingtheDiskintheeAurigaeSystem:aBriefReviewWithProposedNumericalSolutions RichardL.PearsonIIIandRobertE.Stencel 802 ThePulsationalBehavioroftheHighAmplitudedScutiStarRSGruis JaimeRubénGarcía 272 StellarPhotometryWithDSLR:BenchmarkofTwoColorCorrectionTechniquesToward Johnson’sVJandTychoVT RogerPieri 834

INSTRUMENTATION [See also CCD; VARIABLE STAR OBSERVING] TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 TheAAVSO2011DemographicandBackgroundSurvey AaronPriceandKevinB.Paxson 1010 AAVSOnet:theRoboticTelescopeNetwork(Posterabstract) MikeSimonsen 432 TheAcquisitionofPhotometricData ArloU.Landolt 355 Algorithms+Observations=VStar DavidBenn 852 AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 AnAppreciationofClintonB.FordandtheAAVSOofFiftyYearsAgo TonyHull 203 AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData(Posterabstract) MarcoCiocca,EthanE.Kilgore,andWestleyW.Williams 433 BritishAstronomicalAssociationVariableStarSection,1890–2011 JohnToone 154 CataclysmicVariablesintheBackyard(Abstract) JosephPatterson 240 ClassicalandRecurrentNovae UlisseMunari 582 ContributionsbyCitizenScientiststoAstronomy(Abstract) ArneA.Henden 239 DataRelease3oftheAAVSOAll-SkyPhotometricSurvey(APASS)(Posterabstract) ArneA.Hendenet al. 430 dScorpii2011Periastron:VisualandDigitalPhotometricCampaign(Posterabstract) CostantinoSigismondiSapienza 419 ADemonstrationofAccurateWide-fieldV-bandPhotometryUsingaConsumer-gradeDSLRCamera BrianK.Kloppenborget al. 815 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 EnhancingtheEducationalAstronomicalExperienceofNon-ScienceMajorsWiththe UseofaniPadandTelescope(Abstract) RobertM.GillandMichaelJ.Burin 1037 FastSpectrometerConstructionandTesting(Abstract) JohnMenke 1037 FrankElmoreRossandHisVariableStarDiscoveries WayneOsborn 133 HaEmissionExtractionUsingNarrowbandPhotometricFilters(Abstract) GaryWalker 432 HowAmateursCanContributetotheFieldofTransitingExoplanets BryceCroll 456

Index, JAAVSO Volume 40, 20121080 Illinois—WhereAstronomicalPhotometryGrewUp BarryB.BeamanandMichaelT.Svec 141 IntensiveObservationsofCataclysmic,RRLyrae,andHighAmplitudedScuti(HADS) VariableStars Franz-JosefHambsch 289 InterferometryandtheCepheidDistanceScale ThomasG.BarnesIII 256 IntroductiontotheJointAAS-AAVSOScientificPaperSessions MatthewR.Templeton 226 ANoteontheVariabilityofV538Cassiopeiae GustavHolmberg 986 ObservationsUsingaBespokeMediumResolutionFastSpectrograph(Abstract) JohnMenke 1037 AnOverviewoftheAAVSO’sInformationTechnologyInfrastructureFrom1967to1997 RichardC.S.Kinne 208 PlanetHuntingWithHATNetandHATSouth(Abstract) GasparBakos 241 PolarimetryofeAurigae,FromNovember2009toJanuary2012 GaryM.Cole 787 ProgressReportforAdaptingAPASSDataReleasesfortheCalibrationofHarvardPlates EdwardJ.Los 396 TheRASNZPhotometrySection,IncorporatingtheAucklandPhotoelectricObservers’ Group(Posterabstract) StanWalker 177 ReportFromtheeAurigaeCampaigninGreece GrigorisMaraveliaset al. 679 ROAD(RemoteObservatoryAtacamaDesert):IntensiveObservationsofVariableStars Franz-JosefHambsch 1003 ASingleBeamPolarimeter(Posterabstract) JerryD.Horne 1038 SmallTelescopeInfraredPhotometryoftheeAurigaeEclipse ThomasP.Rutherford 704 SolarCycle24—WillItBeUnusuallyQuiet?(Abstract) RodneyHowe 435 SpectroscopicResultsFromBlueHillsObservatoryofthe2009–2011EclipseofeAurigae StanleyA.Gorodenski 743 Spots,Eclipses,andPulsation:theInterplayofPhotometryandOpticalInterferometric Imaging(Abstract) BrianK.Kloppenborg 266 StatusoftheUSNOInfraredAstrometryProgram(Posterabstract) FrederickJohnVrbaet al. 434 StellarPhotometryWithDSLR:BenchmarkofTwoColorCorrectionTechniquesToward Johnson’sVJandTychoVT RogerPieri 834 VariableStarObserversIHaveKnown CharlesE.Scovil 196 VariableStarObservingWiththeBradfordRoboticTelescope(Abstract) RichardC.S.Kinne 435 TheVisualEraoftheAAVSOEclipsingBinaryProgram DavidB.Williams,MarvinE.Baldwin,andGerardSamolyk 180 VSXJ071108.7+695227:aNewlyDiscoveredShort-periodEclipsingBinary MarioDamasso et al. 945 WalkingWithAAVSOGiants—aPersonalJourney(1960s) RogerS.KolmanandMikeSimonsen 189 The“WerkgroepVeranderlijkeSterren”ofBelgium PatrickWilset al. 164

Index, JAAVSO Volume 40, 2012 1081INTERFEROMETRY eAurigae—anOverviewofthe2009–2011EclipseCampaignResults RobertE.Stencel 618 InterferometryandtheCepheidDistanceScale ThomasG.BarnesIII 256 IntroductiontotheJointAAS-AAVSOScientificPaperSessions MatthewR.Templeton 226 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 Miras LeeAnneWillsonandMassimoMarengo 516 ProbingMiraAtmospheresUsingOpticalInterferometricTechniques(Abstract) SamRagland 265 Spots,Eclipses,andPulsation:theInterplayofPhotometryandOpticalInterferometric Imaging(Abstract) BrianK.Kloppenborg 266 VariableStarsandtheAsymptoticGiantBranch:StellarPulsations,DustProduction, andMassLoss AngelaK.Speck 244

INTERSTELLAR MEDIUM Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 VariableStarsandtheAsymptoticGiantBranch:StellarPulsations,DustProduction, andMassLoss AngelaK.Speck 244

IRREGULAR VARIABLES [See also VARIABLE STARS (GENERAL)] ANoteontheVariabilityofV538Cassiopeiae GustavHolmberg 986

JETS (COLLIMATED OUTFLOWS) TheVariabilityofYoungStellarObjects WilliamHerbst 448

LARGE MAGELLANIC CLOUD (LMC) ACenturyofSupernovae PeterGarnavich 598 ClassicalCepheidsAfter228YearsofStudy DavidG.Turner 502 InterferometryandtheCepheidDistanceScale ThomasG.BarnesIII 256 Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds DouglasL.Welch 492 WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539

LIGHT POLLUTION AdverseHealthEffectsofNighttimeLighting MarioMotta 380 StarWatchingPromotedbytheMinistryoftheEnvironment,Japan SeiichiSakuma 391

Index, JAAVSO Volume 40, 20121082LONG-PERIOD VARIABLES [See MIRA VARIABLES; SEMIREGULAR VARIABLES]

LUNAR AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData(Posterabstract) MarcoCiocca,EthanE.Kilgore,andWestleyW.Williams 433

MAGNETIC VARIABLES; POLARS [See also VARIABLE STARS (GENERAL)] CataclysmicVariablesintheBackyard(Abstract) JosephPatterson 240 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94

MATHEMATICS, HISTORY OF AnneS.Young:ProfessorandVariableStarObserverExtraordinaire KatherineBracher 24

MICROVARIABLES Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442

MINOR PLANETS [See ASTEROIDS]

MIRA VARIABLES [See also VARIABLE STARS (GENERAL)] ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics JohnR.Percy 230 Miras LeeAnneWillsonandMassimoMarengo 516 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 ProbingMiraAtmospheresUsingOpticalInterferometricTechniques(Abstract) SamRagland 265 VariableStarObservingWiththeBradfordRoboticTelescope(Abstract) RichardC.S.Kinne 435 WhatMassLossModelingTellsUsAboutPlanetaryNebulae(Abstract) LeeAnneWillsonandQianWang 424

MODELS, STELLAR AnAnalysisoftheLong-termPhotometricBehaviorofeAurigae BrianK.Kloppenborg,JeffreyL.Hopkins,andRobertE.Stencel 647 ACenturyofSupernovae PeterGarnavich 598 CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 ClassicalandRecurrentNovae UlisseMunari 582 ClassicalCepheidsAfter228YearsofStudy DavidG.Turner 502

Index, JAAVSO Volume 40, 2012 1083 TheDevelopmentofEarlyPulsationTheory,or,HowCepheidsAreLikeSteamEngines MatthewStanley 100 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 eAurigae—anOverviewofthe2009–2011EclipseCampaignResults RobertE.Stencel 618 GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis PierredePonthièreet al. 904 GSC4552-1643:aWUMaSystemWithCompleteEclipses DirkTerrellandJohnGross 941 HaSpectralMonitoringofeAurigae2009–2011Eclipse BenjaminMauclaireet al. 718 HowAmateursCanContributetotheFieldofTransitingExoplanets BryceCroll 456 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 TheInternationaleAurigaeCampaign2009PhotometryReport JeffreyL.Hopkins 633 JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 Miras LeeAnneWillsonandMassimoMarengo 516 ModelingtheDiskintheeAurigaeSystem:aBriefReviewWithProposedNumericalSolutions RichardL.PearsonIIIandRobertE.Stencel 802 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 RRLyraeStars:CosmicLighthousesWithaTwist KatrienKolenberg 481 Spots,Eclipses,andPulsation:theInterplayofPhotometryandOpticalInterferometric Imaging(Abstract) BrianK.Kloppenborg 266 StellarPulsationTheoryFromArthurStanleyEddingtontoToday(Abstract) StevenD.KawalerandCarlJ.Hansen 150 SymbioticStars UlisseMunari 572 ThingsWeDon’tUnderstandAboutRRLyraeStars HoraceA.Smith 327 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222 Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds DouglasL.Welch 492 TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 UV-Blue(CCD)andHistoric(Photographic)SpectraofeAurigae—Summary R.ElizabethGriffinandRobertE.Stencel 714 TheVariabilityofYoungStellarObjects WilliamHerbst 448 WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539 WhatMassLossModelingTellsUsAboutPlanetaryNebulae(Abstract) LeeAnneWillsonandQianWang 424 TheWorld’sStrangestSupernovaMayNotBeaSupernovaAtAll(Abstract) CarolineMoore 421

MULTI-SITE OBSERVATIONS [See COORDINATED OBSERVATIONS]

Index, JAAVSO Volume 40, 20121084MULTI-WAVELENGTH OBSERVATIONS [See also COORDINATED OBSERVATIONS] TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 AnAmateur-ProfessionalInternationalObservingCampaignfortheEPOXIMission: NewInsightsIntoComets(Abstract) KarenJ.Meech 422 BrightNewType-IaSupernovainthePinwheelGalaxy(M101):PhysicalPropertiesof SN2011feFromPhotometryandSpectroscopy(Posterabstract) SaiGouravajhalaet al. 419 CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 ClassicalandRecurrentNovae UlisseMunari 582 eAurigae—anOverviewofthe2009–2011EclipseCampaignResults RobertE.Stencel 618 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 Spots,Eclipses,andPulsation:theInterplayofPhotometryandOpticalInterferometric Imaging(Abstract) BrianK.Kloppenborg 266 SymbioticStars UlisseMunari 572 Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 UV-Blue(CCD)andHistoric(Photographic)SpectraofeAurigae—Summary R.ElizabethGriffinandRobertE.Stencel 714

NETWORKS, COMMUNICATION; ELECTRONIC COMMUNICATION TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 AAVSOnet:theRoboticTelescopeNetwork(Posterabstract) MikeSimonsen 432 AboutThis100thAnniversaryIssue JohnR.Percy 1 BritishAstronomicalAssociationVariableStarSection,1890–2011 JohnToone 154 CollaborativeResearchEffortsforCitizenScientists(Posterabstract) BrianK.Kloppenborget al. 426 DataEvolutioninVSX:MakingaGoodThingBetter(Abstract) SebastianOtero 431 TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 AnOverviewoftheAAVSO’sInformationTechnologyInfrastructureFrom1967to1997 RichardC.S.Kinne 208 PlanetHuntingWithHATNetandHATSouth(Abstract) GasparBakos 241 ROAD(RemoteObservatoryAtacamaDesert):IntensiveObservationsofVariableStars Franz-JosefHambsch 1003 TheVisualEraoftheAAVSOEclipsingBinaryProgram DavidB.Williams,MarvinE.Baldwin,andGerardSamolyk 180

Index, JAAVSO Volume 40, 2012 1085 VSX:theNextGeneration(Abstract) ChristopherL.Watson 431

NIGHT VISION AdverseHealthEffectsofNighttimeLighting MarioMotta 380

NOVAE, HISTORICAL ClassicalandRecurrentNovae UlisseMunari 582

NOVAE; RECURRENT NOVAE; NOVA-LIKE [See also CATACLYSMIC VARIABLES] AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 BritishAstronomicalAssociationVariableStarSection,1890–2011 JohnToone 154 CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 CataclysmicVariablesintheBackyard(Abstract) JosephPatterson 240 ClassicalandRecurrentNovae UlisseMunari 582 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 NewLightCurveforthe1909OutburstofRTSerpentis GrantLuberdaandWayneOsborn 887 ROAD(RemoteObservatoryAtacamaDesert):IntensiveObservationsofVariableStars Franz-JosefHambsch 1003 AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 SymbioticStars UlisseMunari 572 Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94

OBITUARIES, MEMORIALS [See also ASTRONOMY, HISTORY OF] AnAppreciationofClintonB.FordandtheAAVSOofFiftyYearsAgo TonyHull 203 GuidingForcesandJanetA.Mattei ElizabethO.Waagen 65 IntroductiontotheHistoryPaperSessions ThomasR.Williams 20 VariableStarObserversIHaveKnown CharlesE.Scovil 196 VariableStarsandConstantCommitments:theStellarCareerofDorritHoffleit KristineLarsen 44

OBSERVATORIES AnneS.Young:ProfessorandVariableStarObserverExtraordinaire KatherineBracher 24 Apollo14RoadTrip(Posterabstract) PaulValleli 223 AnAppreciationofClintonB.FordandtheAAVSOofFiftyYearsAgo TonyHull 203

Index, JAAVSO Volume 40, 20121086 AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData(Posterabstract) MarcoCiocca,EthanE.Kilgore,andWestleyW.Williams 433 BritishAstronomicalAssociationVariableStarSection,1890–2011 JohnToone 154 FrankElmoreRossandHisVariableStarDiscoveries WayneOsborn 133 HaEmissionExtractionUsingNarrowbandPhotometricFilters(Abstract) GaryWalker 432 Illinois—WhereAstronomicalPhotometryGrewUp BarryB.BeamanandMichaelT.Svec 141 IntensiveObservationsofCataclysmic,RRLyrae,andHighAmplitudedScuti(HADS) VariableStars Franz-JosefHambsch 289 TheLegacyofAnnieJumpCannon:DiscoveriesandCataloguesofVariableStars(Abstract) BarbaraL.Welther 92 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 TheRASNZPhotometrySection,IncorporatingtheAucklandPhotoelectricObservers’ Group(Posterabstract) StanWalker 177 TheRASNZVariableStarSectionandVariableStarsSouth AlbertJonesandStanWalker 168 ReminiscencesontheCareerofMarthaStahrCarpenter:BetweenaRockand(Several)HardPlaces KristineLarsen 51 ROAD(RemoteObservatoryAtacamaDesert):IntensiveObservationsofVariableStars Franz-JosefHambsch 1003 TheStarsBelongtoEveryone:AstronomerandScienceWriterHelenSawyerHogg(1905–1993) MariaJ.Cahill 31 StatusoftheUSNOInfraredAstrometryProgram(Posterabstract) FrederickJohnVrbaet al. 434 TheVariableStarObservationsofFrankE.Seagrave(Abstract) GeraldP.Dyck 223 VariableStarObserversIHaveKnown CharlesE.Scovil 196 VariableStarObservingWiththeBradfordRoboticTelescope(Abstract) RichardC.S.Kinne 435 VariableStarsandConstantCommitments:theStellarCareerofDorritHoffleit KristineLarsen 44 WalkingWithAAVSOGiants—aPersonalJourney(1960s) RogerS.KolmanandMikeSimonsen 189 TheWorldScienceFestival(Abstract) JohnPazmino 428

P CYGNI STARS InternationalObservingCampaign:PhotometryandSpectroscopyofPCygni ErnstPollmannandThiloBauer 894 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442

PERIOD ANALYSIS; PERIOD CHANGES TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 Algorithms+Observations=VStar DavidBenn 852 AnAnalysisoftheLong-termPhotometricBehaviorofeAurigae BrianK.Kloppenborg,JeffreyL.Hopkins,andRobertE.Stencel 647

Index, JAAVSO Volume 40, 2012 1087 CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 CataclysmicVariablesintheBackyard(Abstract) JosephPatterson 240 ClassicalCepheidsAfter228YearsofStudy DavidG.Turner 502 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis PierredePonthièreet al. 904 GSC4552-1643:aWUMaSystemWithCompleteEclipses DirkTerrellandJohnGross 941 HighSchoolStudentsWatchingStarsEvolve(Abstract) JohnR.Percyet al. 416 HighSpeedUBVPhotometryofeAurigae’s2009–2011Eclipse(Posterabstract) AaronPriceet al. 418 HowAmateursCanContributetotheFieldofTransitingExoplanets BryceCroll 456 TheInternationaleAurigaeCampaign2009PhotometryReport JeffreyL.Hopkins 633 LightCurveofMinorPlanet1026Ingrid(Posterabstract) ShelbyDelos,GaryAhrendts,andTimothyBaker 423 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics JohnR.Percy 230 NewLightCurveforthe1909OutburstofRTSerpentis GrantLuberdaandWayneOsborn 887 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 ANoteontheVariabilityofV538Cassiopeiae GustavHolmberg 986 PhotoelectricPhotometryofeAurigaeDuringthe2009–2011EclipseSeason FrankJ.Melillo 695 PlanetHuntingWithHATNetandHATSouth(Abstract) GasparBakos 241 ThePulsationPeriodoftheHotHydrogen-DeficientStarMVSgr JohnR.PercyandRongFu 900 ThePulsationalBehavioroftheHighAmplitudedScutiStarRSGruis JaimeRubénGarcía 272 RecentMaximaof55ShortPeriodPulsatingStars GerardSamolyk 923 RecentMinimaof150EclipsingBinaryStars GerardSamolyk 975 ReportFromtheeAurigaeCampaigninGreece GrigorisMaraveliaset al. 679 ROAD(RemoteObservatoryAtacamaDesert):IntensiveObservationsofVariableStars Franz-JosefHambsch 1003 RRLyraeStars:CosmicLighthousesWithaTwist KatrienKolenberg 481 RSSagittae:theSearchforEclipses JerryD.Horne 278 Spots,Eclipses,andPulsation:theInterplayofPhotometryandOpticalInterferometric Imaging(Abstract) BrianK.Kloppenborg 266 AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295

Index, JAAVSO Volume 40, 20121088 ThingsWeDon’tUnderstandAboutRRLyraeStars HoraceA.Smith 327 Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 V-bandLightCurveAnalysisofeAurigaeDuringthe2009–2011Eclipse ThomasKarlsson 668 TheVariabilityofYoungStellarObjects WilliamHerbst 448 VariabilityTypeDeterminationandHighPrecisionEphemerisforNSVS7606408 RiccardoFurgoni 955 TheVariableStarsSouthEclipsingBinaryDatabase TomRichards 983 VSXJ071108.7+695227:aNewlyDiscoveredShort-periodEclipsingBinary MarioDamasso et al. 945 TheZCamPaignEarlyResults(Abstract) MikeSimonsen 241

PHOTOELECTRIC PHOTOMETRY [See PHOTOMETRY, PHOTOELECTRIC]

PHOTOGRAPHY FrankElmoreRossandHisVariableStarDiscoveries WayneOsborn 133 Hubble’sFamousPlateof1923:aStoryofPinkPolyethylene DavidR.Soderblom 321 NewLifeforOldData:DigitizationofDataPublishedintheHarvardAnnals(Abstract) MatthewR.Templetonet al. 429

PHOTOMETRY TheAcquisitionofPhotometricData ArloU.Landolt 355 ClassicalandRecurrentNovae UlisseMunari 582 EclipsingBinariesThatDon’tEclipseAnymore:theStrangeCaseoftheOnce (andFuture?)EclipsingBinaryQXCassiopeiae(Abstract) EdwardF.Guinanet al. 417 HaEmissionExtractionUsingNarrowbandPhotometricFilters(Abstract) GaryWalker 432 TheInternationaleAurigaeCampaign2009PhotometryReport JeffreyL.Hopkins 633 IntroductiontotheJointAAS-AAVSOScientificPaperSessions MatthewR.Templeton 226 ProgressReportforAdaptingAPASSDataReleasesfortheCalibrationofHarvardPlates EdwardJ.Los 396 Spots,Eclipses,andPulsation:theInterplayofPhotometryandOpticalInterferometric Imaging(Abstract) BrianK.Kloppenborg 266

PHOTOMETRY, CCD AAVSOEstimatesandtheNatureofTypeCSemiregulars:ProgenitorsofTypeIISupernovae(Abstract) DavidG.Turneret al. 415 AAVSOnet:theRoboticTelescopeNetwork(Posterabstract) MikeSimonsen 432 TheAcquisitionofPhotometricData ArloU.Landolt 355 AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348

Index, JAAVSO Volume 40, 2012 1089 AnAnalysisoftheLong-termPhotometricBehaviorofeAurigae BrianK.Kloppenborg,JeffreyL.Hopkins,andRobertE.Stencel 647 AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData(Posterabstract) MarcoCiocca,EthanE.Kilgore,andWestleyW.Williams 433 BrightNewType-IaSupernovainthePinwheelGalaxy(M101):PhysicalPropertiesof SN2011feFromPhotometryandSpectroscopy(Posterabstract) SaiGouravajhalaet al. 419 BVRIPhotometryofSN2011feinM101 MichaelW.RichmondandHoraceA.Smith 872 CataclysmicVariablesintheBackyard(Abstract) JosephPatterson 240 ClassicalandRecurrentNovae UlisseMunari 582 DataRelease3oftheAAVSOAll-SkyPhotometricSurvey(APASS)(Posterabstract) ArneA.Hendenet al. 430 dScorpii2011Periastron:VisualandDigitalPhotometricCampaign(Posterabstract) CostantinoSigismondiSapienza 419 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 EclipsingBinariesThatDon’tEclipseAnymore:theStrangeCaseoftheOnce (andFuture?)EclipsingBinaryQXCassiopeiae(Abstract) EdwardF.Guinanet al. 417 eAurigae—anOverviewofthe2009–2011EclipseCampaignResults RobertE.Stencel 618 GSC4552-1643:aWUMaSystemWithCompleteEclipses DirkTerrellandJohnGross 941 GuidingForcesandJanetA.Mattei ElizabethO.Waagen 65 HighSchoolStudentsWatchingStarsEvolve(Abstract) JohnR.Percyet al. 416 HighSpeedUBVPhotometryofeAurigae’s2009–2011Eclipse(Posterabstract) AaronPriceet al. 418 HistoryofAmateurVariableStarObservationsinJapan(Posterabstract) SeiichiroKiyota 178 TheHuntfortheQuark-Nova;aCallforObservers(Abstract) DavidJ.Laneet al. 425 TheInternationaleAurigaeCampaign2009PhotometryReport JeffreyL.Hopkins 633 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 MembershipofthePlanetaryNebulaAbell8intheOpenClusterBica6andImplicationsfor thePNDistanceScale(Posterabstract) DavidG.Turneret al. 423 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 ANoteontheVariabilityofV538Cassiopeiae GustavHolmberg 986 TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 APracticalApproachtoTransformingMagnitudesontoaStandardPhotometricSystem DavidBoyd 990 PreliminaryAnalysisofMOSTObservationsoftheTrapezium(Abstract) MatthewR.Templetonet al. 415 ProgressReportforAdaptingAPASSDataReleasesfortheCalibrationofHarvardPlates EdwardJ.Los 396

Index, JAAVSO Volume 40, 20121090 ThePulsationPeriodoftheHotHydrogen-DeficientStarMVSgr JohnR.PercyandRongFu 900 ThePulsationalBehavioroftheHighAmplitudedScutiStarRSGruis JaimeRubénGarcía 272 TheRASNZPhotometrySection,IncorporatingtheAucklandPhotoelectricObservers’ Group(Posterabstract) StanWalker 177 RecentMaximaof55ShortPeriodPulsatingStars GerardSamolyk 923 RecentMinimaof150EclipsingBinaryStars GerardSamolyk 975 ReportFromtheeAurigaeCampaigninGreece GrigorisMaraveliaset al. 679 ROAD(RemoteObservatoryAtacamaDesert):IntensiveObservationsofVariableStars Franz-JosefHambsch 1003 SecularVariationoftheModeAmplitude-RatiooftheDouble-ModeRRLyraeStar NSVS5222076,Part2 DavidA.HurdisandTomKrajci 268 StatusoftheUSNOInfraredAstrometryProgram(Posterabstract) FrederickJohnVrbaet al. 434 AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 SymbioticStars UlisseMunari 572 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222 UV-Blue(CCD)andHistoric(Photographic)SpectraofeAurigae—Summary R.ElizabethGriffinandRobertE.Stencel 714 VariableStarObservingWiththeBradfordRoboticTelescope(Abstract) RichardC.S.Kinne 435 TheVariableStarsSouthEclipsingBinaryDatabase TomRichards 983 TheVisualEraoftheAAVSOEclipsingBinaryProgram DavidB.Williams,MarvinE.Baldwin,andGerardSamolyk 180 VSXJ071108.7+695227:aNewlyDiscoveredShort-periodEclipsingBinary MarioDamasso et al. 945 The“WerkgroepVeranderlijkeSterren”ofBelgium PatrickWilset al. 164

PHOTOMETRY, DSLR ADemonstrationofAccurateWide-fieldV-bandPhotometryUsingaConsumer-gradeDSLRCamera BrianK.Kloppenborget al. 815 TheInternationaleAurigaeCampaign2009PhotometryReport JeffreyL.Hopkins 633 ReportFromtheeAurigaeCampaigninGreece GrigorisMaraveliaset al. 679 StellarPhotometryWithDSLR:BenchmarkofTwoColorCorrectionTechniquesToward Johnson’sVJandTychoVT RogerPieri 834 TheVariableStarsSouthEclipsingBinaryDatabase TomRichards 983

PHOTOMETRY, HISTORY OF TheAcquisitionofPhotometricData ArloU.Landolt 355 Illinois—WhereAstronomicalPhotometryGrewUp BarryB.BeamanandMichaelT.Svec 141

Index, JAAVSO Volume 40, 2012 1091PHOTOMETRY, INFRARED eAurigae—anOverviewofthe2009–2011EclipseCampaignResults RobertE.Stencel 618 IntroductiontotheJointAAS-AAVSOScientificPaperSessions MatthewR.Templeton 226 SmallTelescopeInfraredPhotometryoftheeAurigaeEclipse ThomasP.Rutherford 704 Spots,Eclipses,andPulsation:theInterplayofPhotometryandOpticalInterferometric Imaging(Abstract) BrianK.Kloppenborg 266

PHOTOMETRY, NEAR-INFRARED TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 AnAnalysisoftheLong-termPhotometricBehaviorofeAurigae BrianK.Kloppenborg,JeffreyL.Hopkins,andRobertE.Stencel 647 eAurigae—anOverviewofthe2009–2011EclipseCampaignResults RobertE.Stencel 618 TheInternationaleAurigaeCampaign2009PhotometryReport JeffreyL.Hopkins 633 IntroductiontotheJointAAS-AAVSOScientificPaperSessions MatthewR.Templeton 226 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 ProbingMiraAtmospheresUsingOpticalInterferometricTechniques(Abstract) SamRagland 265 Spots,Eclipses,andPulsation:theInterplayofPhotometryandOpticalInterferometric Imaging(Abstract) BrianK.Kloppenborg 266 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222 TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 VariableStarsandtheAsymptoticGiantBranch:StellarPulsations,DustProduction,andMassLoss AngelaK.Speck 244

PHOTOMETRY, PHOTOELECTRIC AAVSOEstimatesandtheNatureofTypeCSemiregulars:ProgenitorsofTypeIISupernovae(Abstract) DavidG.Turneret al. 415 TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 TheAcquisitionofPhotometricData ArloU.Landolt 355 AnAnalysisoftheLong-termPhotometricBehaviorofeAurigae BrianK.Kloppenborg,JeffreyL.Hopkins,andRobertE.Stencel 647 AnAppreciationofClintonB.FordandtheAAVSOofFiftyYearsAgo TonyHull 203 BritishAstronomicalAssociationVariableStarSection,1890–2011 JohnToone 154 ClassicalandRecurrentNovae UlisseMunari 582 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 EclipsingBinariesThatDon’tEclipseAnymore:theStrangeCaseoftheOnce (andFuture?)EclipsingBinaryQXCassiopeiae(Abstract) EdwardF.Guinanet al. 417

Index, JAAVSO Volume 40, 20121092 eAurigae—anOverviewofthe2009–2011EclipseCampaignResults RobertE.Stencel 618 HistoryofAmateurVariableStarObservationsinJapan(Posterabstract) SeiichiroKiyota 178 Illinois—WhereAstronomicalPhotometryGrewUp BarryB.BeamanandMichaelT.Svec 141 TheInternationaleAurigaeCampaign2009PhotometryReport JeffreyL.Hopkins 633 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 PhotoelectricPhotometryofeAurigaeDuringthe2009–2011EclipseSeason FrankJ.Melillo 695 TheRASNZPhotometrySection,IncorporatingtheAucklandPhotoelectricObservers’ Group(Posterabstract) StanWalker 177 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222 TheVisualEraoftheAAVSOEclipsingBinaryProgram DavidB.Williams,MarvinE.Baldwin,andGerardSamolyk 180

PHOTOMETRY, PHOTOGRAPHIC TheAcquisitionofPhotometricData ArloU.Landolt 355 AnneS.Young:ProfessorandVariableStarObserverExtraordinaire KatherineBracher 24 BritishAstronomicalAssociationVariableStarSection,1890–2011 JohnToone 154 ClassicalandRecurrentNovae UlisseMunari 582 dScorpii2011Periastron:VisualandDigitalPhotometricCampaign(Posterabstract) CostantinoSigismondiSapienza 419 DigitalArchiving:WherethePastLivesAgain KevinB.Paxson 360 FrankElmoreRossandHisVariableStarDiscoveries WayneOsborn 133 IsMPGeminorumanEclipsingBinaryWithaVeryLongPeriod? DietmarBöhme 973 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 NewLightCurveforthe1909OutburstofRTSerpentis GrantLuberdaandWayneOsborn 887 ANoteontheVariabilityofV538Cassiopeiae GustavHolmberg 986 TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 ProgressReportforAdaptingAPASSDataReleasesfortheCalibrationofHarvardPlates EdwardJ.Los 396 TheRossVariableStarsRevisited.II WayneOsbornandO.FrankMills 929 TheStarsBelongtoEveryone:AstronomerandScienceWriterHelenSawyerHogg(1905–1993) MariaJ.Cahill 31 AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295

Index, JAAVSO Volume 40, 2012 1093 SymbioticStars UlisseMunari 572 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222 UV-Blue(CCD)andHistoric(Photographic)SpectraofeAurigae—Summary R.ElizabethGriffinandRobertE.Stencel 714 VariableStarsandConstantCommitments:theStellarCareerofDorritHoffleit KristineLarsen 44

PHOTOMETRY, VISUAL AAVSOEstimatesandtheNatureofTypeCSemiregulars:ProgenitorsofTypeIISupernovae(Abstract) DavidG.Turneret al. 415 TheAcquisitionofPhotometricData ArloU.Landolt 355 AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 AnAnalysisoftheLong-termPhotometricBehaviorofeAurigae BrianK.Kloppenborg,JeffreyL.Hopkins,andRobertE.Stencel 647 AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData(Posterabstract) MarcoCiocca,EthanE.Kilgore,andWestleyW.Williams 433 BritishAstronomicalAssociationVariableStarSection,1890–2011 JohnToone 154 BVRIPhotometryofSN2011feinM101 MichaelW.RichmondandHoraceA.Smith 872 ClassicalandRecurrentNovae UlisseMunari 582 dScorpii2011Periastron:VisualandDigitalPhotometricCampaign(Posterabstract) CostantinoSigismondiSapienza 419 eAurigae—anOverviewofthe2009–2011EclipseCampaignResults RobertE.Stencel 618 HighSchoolStudentsWatchingStarsEvolve(Abstract) JohnR.Percyet al. 416 HistoryofAmateurVariableStarObservationsinJapan(Posterabstract) SeiichiroKiyota 178 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics JohnR.Percy 230 NewLifeforOldData:DigitizationofDataPublishedintheHarvardAnnals(Abstract) MatthewR.Templetonet al. 429 NewLightCurveforthe1909OutburstofRTSerpentis GrantLuberdaandWayneOsborn 887 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 ReportFromtheeAurigaeCampaigninGreece GrigorisMaraveliaset al. 679 AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 SymbioticStars UlisseMunari 572 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222

Index, JAAVSO Volume 40, 20121094 TheVisualEraoftheAAVSOEclipsingBinaryProgram DavidB.Williams,MarvinE.Baldwin,andGerardSamolyk 180 The“WerkgroepVeranderlijkeSterren”ofBelgium PatrickWilset al. 164

PLANETARIUMS TheCitizenSkyPlanetariumTrailer(Posterabstract) RebeccaTurner,AaronPrice,andRyanWyatt 428 TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 TheWorldScienceFestival(Abstract) JohnPazmino 428

PLANETARY NEBULAE MembershipofthePlanetaryNebulaAbell8intheOpenClusterBica6andImplicationsfor thePNDistanceScale(Posterabstract) DavidG.Turneret al. 423 SymbioticStars UlisseMunari 572 WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539 WhatMassLossModelingTellsUsAboutPlanetaryNebulae(Abstract) LeeAnneWillsonandQianWang 424

PLANETS AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData(Posterabstract) MarcoCiocca,EthanE.Kilgore,andWestleyW.Williams 433 ContributionsbyCitizenScientiststoAstronomy(Abstract) ArneA.Henden 239 FrankElmoreRossandHisVariableStarDiscoveries WayneOsborn 133 JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 Stars,Planets,andtheWeather:ifYouDon’tLikeItWaitFiveBillionYears(Abstract) JeremyJ.Drake 425

PLANETS, EXTRASOLAR CentennialHighlightsinAstronomy OwenGingerich 438 ContributionsbyCitizenScientiststoAstronomy(Abstract) ArneA.Henden 239 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 EclipsingBinariesThatDon’tEclipseAnymore:theStrangeCaseoftheOnce (andFuture?)EclipsingBinaryQXCassiopeiae(Abstract) EdwardF.Guinanet al. 417 HowAmateursCanContributetotheFieldofTransitingExoplanets BryceCroll 456 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 PlanetHuntingWithHATNetandHATSouth(Abstract) GasparBakos 241 Stars,Planets,andtheWeather:ifYouDon’tLikeItWaitFiveBillionYears(Abstract) JeremyJ.Drake 425 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222

Index, JAAVSO Volume 40, 2012 1095 TheVariabilityofYoungStellarObjects WilliamHerbst 448

POETRY, THEATER, DANCE, SOCIETY TheAAVSO2011DemographicandBackgroundSurvey AaronPriceandKevinB.Paxson 1010 TheAAVSOWidow—orShouldWeSaySpouse? ThomasR.Williams 77 AdverseHealthEffectsofNighttimeLighting MarioMotta 380 AnneS.Young:ProfessorandVariableStarObserverExtraordinaire KatherineBracher 24 AnArtist’sNoteonArtinScience NicoCamargo 867 BritishAstronomicalAssociationVariableStarSection,1890–2011 JohnToone 154 TheCitizenSkyPlanetariumTrailer(Posterabstract) RebeccaTurner,AaronPrice,andRyanWyatt 428 CollaborativeResearchEffortsforCitizenScientists(Posterabstract) BrianK.Kloppenborget al. 426 ExploringtheBreadthandSourcesofVariableStarAstronomers’AstronomyKnowledge: FirstSteps(Abstract) StephanieJ.Slater 427 Flares,Fears,andForecasts:PublicMisconceptionsAbouttheSunspotCycle KristineLarsen 407 GuidingForcesandJanetA.Mattei ElizabethO.Waagen 65 HighlightingeAurigaeandCitizenSky JohnR.Percy 609 IntroductiontotheHistoryPaperSessions ThomasR.Williams 20 JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 KingCharles’Star:AMultidisciplinaryApproachtoDatingtheSupernovaKnownas CassiopeiaA(Abstract) MartinLunn 150 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 RaschAnalysisofScientificLiteracyinanAstronomicalCitizenScienceProject(Posterabstract) AaronPrice 427 ReportFromtheeAurigaeCampaigninGreece GrigorisMaraveliaset al. 679 StarWatchingPromotedbytheMinistryoftheEnvironment,Japan SeiichiSakuma 391 TheStarsBelongtoEveryone:AstronomerandScienceWriterHelenSawyerHogg(1905–1993) MariaJ.Cahill 31 Stars,Planets,andtheWeather:ifYouDon’tLikeItWaitFiveBillionYears(Abstract) JeremyJ.Drake 425 TheWorldScienceFestival(Abstract) JohnPazmino 428

POLARIMETRY EclipseSpectropolarimetryoftheeAurigaeSystem KathleenM.Geiseet al. 767

Index, JAAVSO Volume 40, 20121096 eAurigae—anOverviewofthe2009–2011EclipseCampaignResults RobertE.Stencel 618 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 PolarimetryofeAurigae,FromNovember2009toJanuary2012 GaryM.Cole 787 ASingleBeamPolarimeter(Posterabstract) JerryD.Horne 1038 TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334

PROFESSIONAL-AMATEUR COLLABORATION [See ASTRONOMERS, AMATEUR]

PULSATING VARIABLES HighSchoolStudentsWatchingStarsEvolve(Abstract) JohnR.Percyet al. 416 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 Miras LeeAnneWillsonandMassimoMarengo 516 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 SecularVariationoftheModeAmplitude-RatiooftheDouble-ModeRRLyraeStar NSVS5222076,Part2 DavidA.HurdisandTomKrajci 268 Spots,Eclipses,andPulsation:theInterplayofPhotometryandOpticalInterferometric Imaging(Abstract) BrianK.Kloppenborg 266 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222 WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539

R CORONAE BOREALIS VARIABLES [See also VARIABLE STARS (GENERAL)] ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics JohnR.Percy 230 ThePulsationPeriodoftheHotHydrogen-DeficientStarMVSgr JohnR.PercyandRongFu 900 WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539

RADIAL VELOCITY TheDevelopmentofEarlyPulsationTheory,or,HowCepheidsAreLikeSteamEngines MatthewStanley 100 EclipseSpectropolarimetryoftheeAurigaeSystem KathleenM.Geiseet al. 767 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467

Index, JAAVSO Volume 40, 2012 1097 EclipsingBinariesThatDon’tEclipseAnymore:theStrangeCaseoftheOnce (andFuture?)EclipsingBinaryQXCassiopeiae(Abstract) EdwardF.Guinanet al. 417 eAurigae—anOverviewofthe2009–2011EclipseCampaignResults RobertE.Stencel 618 HighCadenceMeasurementofNeutralSodiumandPotassiumAbsorptionDuringthe 2009–2011EclipseofeAurigae RobinLeadbeateret al. 729 HowAmateursCanContributetotheFieldofTransitingExoplanets BryceCroll 456 InterferometryandtheCepheidDistanceScale ThomasG.BarnesIII 256 MembershipofthePlanetaryNebulaAbell8intheOpenClusterBica6andImplicationsfor thePNDistanceScale(Posterabstract) DavidG.Turneret al. 423 ObservationsUsingaBespokeMediumResolutionFastSpectrograph(Abstract) JohnMenke 1037 TheRotationalPeriodoftheSunUsingtheDopplerShiftoftheHaSpectralLine(Abstract) RobertM.Gill 1038 SpectroscopicResultsFromBlueHillsObservatoryofthe2009–2011EclipseofeAurigae StanleyA.Gorodenski 743

RADIO ASTRONOMY; RADIO OBSERVATIONS AnAmateur-ProfessionalInternationalObservingCampaignfortheEPOXIMission: NewInsightsIntoComets(Abstract) KarenJ.Meech 422 ProbingMiraAtmospheresUsingOpticalInterferometricTechniques(Abstract) SamRagland 265 ReminiscencesontheCareerofMarthaStahrCarpenter:BetweenaRockand(Several)HardPlaces KristineLarsen 51

RED VARIABLES [See IRREGULAR, MIRA, SEMIREGULAR VARIABLES]

REMOTE OBSERVING AAVSOnet:theRoboticTelescopeNetwork(Posterabstract) MikeSimonsen 432 GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis PierredePonthièreet al. 904 IntensiveObservationsofCataclysmic,RRLyrae,andHighAmplitudedScuti(HADS) VariableStars Franz-JosefHambsch 289 LightCurveofMinorPlanet1026Ingrid(Posterabstract) ShelbyDelos,GaryAhrendts,andTimothyBaker 423 ANoteontheVariabilityofV538Cassiopeiae GustavHolmberg 986 ROAD(RemoteObservatoryAtacamaDesert):IntensiveObservationsofVariableStars Franz-JosefHambsch 1003 SecularVariationoftheModeAmplitude-RatiooftheDouble-ModeRRLyraeStar NSVS5222076,Part2 DavidA.HurdisandTomKrajci 268 The“WerkgroepVeranderlijkeSterren”ofBelgium PatrickWilset al. 164

ROTATING VARIABLES [See also VARIABLE STARS (GENERAL)] Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442

Index, JAAVSO Volume 40, 20121098 Spots,Eclipses,andPulsation:theInterplayofPhotometryandOpticalInterferometric Imaging(Abstract) BrianK.Kloppenborg 266

RR LYRAE STARS [See also VARIABLE STARS (GENERAL)] AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData(Posterabstract) MarcoCiocca,EthanE.Kilgore,andWestleyW.Williams 433 TheGEOSAssociationofVariableStarObservers(Abstract) Franz-JosefHambschet al. 177 GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis PierredePonthièreet al. 904 HighSchoolStudentsWatchingStarsEvolve(Abstract) JohnR.Percyet al. 416 IntensiveObservationsofCataclysmic,RRLyrae,andHighAmplitudedScuti(HADS) VariableStarsFranz-JosefHambsch 289 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 RecentMaximaof55ShortPeriodPulsatingStars GerardSamolyk 923 ROAD(RemoteObservatoryAtacamaDesert):IntensiveObservationsofVariableStars Franz-JosefHambsch 1003 RRLyraeStars:CosmicLighthousesWithaTwist KatrienKolenberg 481 SecularVariationoftheModeAmplitude-RatiooftheDouble-ModeRRLyraeStar NSVS5222076,Part2 DavidA.HurdisandTomKrajci 268 ThingsWeDon’tUnderstandAboutRRLyraeStars HoraceA.Smith 327

RS CVN STARS [See ECLIPSING BINARIES; see also VARIABLE STARS (GENERAL)]

RV TAURI STARS [See also VARIABLE STARS (GENERAL)] ClassicalCepheidsAfter228YearsofStudy DavidG.Turner 502 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics JohnR.Percy 230 Miras LeeAnneWillsonandMassimoMarengo 516 RSSagittae:theSearchforEclipses JerryD.Horne 278 Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds DouglasL.Welch 492

S DORADUS VARIABLES [See also VARIABLE STARS (GENERAL)] Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442

SATELLITE OBSERVATIONS ACenturyofSupernovae PeterGarnavich 598

Index, JAAVSO Volume 40, 2012 1099 CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 ClassicalCepheidsAfter228YearsofStudy DavidG.Turner 502 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 EclipsingBinariesThatDon’tEclipseAnymore:theStrangeCaseoftheOnce (andFuture?)EclipsingBinaryQXCassiopeiae(Abstract) EdwardF.Guinanet al. 417 eAurigae—anOverviewofthe2009–2011EclipseCampaignResults RobertE.Stencel 618 GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis PierredePonthièreet al. 904 HowAmateursCanContributetotheFieldofTransitingExoplanets BryceCroll 456 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 InterferometryandtheCepheidDistanceScale ThomasG.BarnesIII 256 IntroductiontotheJointAAS-AAVSOScientificPaperSessions MatthewR.Templeton 226 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 Miras LeeAnneWillsonandMassimoMarengo 516 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 PreliminaryAnalysisofMOSTObservationsoftheTrapezium(Abstract) MatthewR.Templetonet al. 415 RRLyraeStars:CosmicLighthousesWithaTwist KatrienKolenberg 481 Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334

SATELLITES; SATELLITE/SPACECRAFT MISSIONS [See also COORDINATED OBSERVATIONS] AnAmateur-ProfessionalInternationalObservingCampaignfortheEPOXIMission: NewInsightsIntoComets(Abstract) KarenJ.Meech 422 CentennialHighlightsinAstronomy OwenGingerich 438 ACenturyofSupernovae PeterGarnavich 598 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 GuidingForcesandJanetA.Mattei ElizabethO.Waagen 65 Hubble’sFamousPlateof1923:aStoryofPinkPolyethylene DavidR.Soderblom 321 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 IntroductiontotheJointAAS-AAVSOScientificPaperSessions MatthewR.Templeton 226 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442

Index, JAAVSO Volume 40, 20121100 Miras LeeAnneWillsonandMassimoMarengo 516 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 AnOverviewoftheAAVSO’sInformationTechnologyInfrastructureFrom1967to1997 RichardC.S.Kinne 208 RRLyraeStars:CosmicLighthousesWithaTwist KatrienKolenberg 481 Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94

SCIENTIFIC WRITING, PUBLICATION OF DATA AnArtist’sNoteonArtinScience NicoCamargo 867 TheCitationofManuscriptsWhichHaveAppearedinJAAVSO ArloU.Landolt 1032 ReminiscencesontheCareerofMarthaStahrCarpenter:BetweenaRockand(Several)HardPlaces KristineLarsen 51

SELF-CORRELATION ANALYSIS TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics JohnR.Percy 230 ThePulsationPeriodoftheHotHydrogen-DeficientStarMVSgr JohnR.PercyandRongFu 900 RSSagittae:theSearchforEclipses JerryD.Horne 278

SEMIREGULAR VARIABLES [See also VARIABLE STARS (GENERAL)] AAVSOEstimatesandtheNatureofTypeCSemiregulars:ProgenitorsofTypeIISupernovae(Abstract) DavidG.Turneret al. 415 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics JohnR.Percy 230 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 PreliminaryAnalysisofMOSTObservationsoftheTrapezium(Abstract) MatthewR.Templetonet al. 415

SEQUENCES, COMPARISON STAR [See CHARTS]

SMALL-AMPLITUDE RED VARIABLES TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528

SOFTWARE [See COMPUTERS]

SOLAR AnneS.Young:ProfessorandVariableStarObserverExtraordinaire KatherineBracher 24

Index, JAAVSO Volume 40, 2012 1101 TheEffectofOnlineSunspotDataonVisualSolarObservers KristineLarsen 374 Flares,Fears,andForecasts:PublicMisconceptionsAbouttheSunspotCycle KristineLarsen 407 AGeneralizedLinearMixedModelforEnumeratedSunspots(Abstract) JamieRiggs 436 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 ReminiscencesontheCareerofMarthaStahrCarpenter:BetweenaRockand(Several)HardPlaces KristineLarsen 51 TheRotationalPeriodoftheSunUsingtheDopplerShiftoftheHaSpectralLine(Abstract) RobertM.Gill 1038 SolarCycle24—WillItBeUnusuallyQuiet?(Abstract) RodneyHowe 435 Stars,Planets,andtheWeather:ifYouDon’tLikeItWaitFiveBillionYears(Abstract) JeremyJ.Drake 425

SPECTRA, SPECTROSCOPY AAVSOEstimatesandtheNatureofTypeCSemiregulars:ProgenitorsofTypeIISupernovae(Abstract) DavidG.Turneret al. 415 BrightNewType-IaSupernovainthePinwheelGalaxy(M101):PhysicalPropertiesof SN2011feFromPhotometryandSpectroscopy(Posterabstract) SaiGouravajhalaet al. 419 BritishAstronomicalAssociationVariableStarSection,1890–2011 JohnToone 154 ClassicalandRecurrentNovae UlisseMunari 582 EclipseSpectropolarimetryoftheeAurigaeSystem KathleenM.Geiseet al. 767 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 EclipsingBinariesThatDon’tEclipseAnymore:theStrangeCaseoftheOnce (andFuture?)EclipsingBinaryQXCassiopeiae(Abstract) EdwardF.Guinanet al. 417 eAurigae—anOverviewofthe2009–2011EclipseCampaignResults RobertE.Stencel 618 FastSpectrometerConstructionandTesting(Abstract) JohnMenke 1037 HaEmissionExtractionUsingNarrowbandPhotometricFilters(Abstract) GaryWalker 432 HaSpectralMonitoringofeAurigae2009–2011Eclipse BenjaminMauclaireet al. 718 HighCadenceMeasurementofNeutralSodiumandPotassiumAbsorptionDuringthe 2009–2011EclipseofeAurigae RobinLeadbeateret al. 729 InternationalObservingCampaign:PhotometryandSpectroscopyofPCygni ErnstPollmannandThiloBauer 894 IntroductiontotheJointAAS-AAVSOScientificPaperSessions MatthewR.Templeton 226 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 MembershipofthePlanetaryNebulaAbell8intheOpenClusterBica6andImplicationsfor thePNDistanceScale(Posterabstract) DavidG.Turneret al. 423

Index, JAAVSO Volume 40, 20121102 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 ObservationsUsingaBespokeMediumResolutionFastSpectrograph(Abstract) JohnMenke 1037 TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 ReportFromtheeAurigaeCampaigninGreece GrigorisMaraveliaset al. 679 TheRotationalPeriodoftheSunUsingtheDopplerShiftoftheHaSpectralLine(Abstract) RobertM.Gill 1038 RRLyraeStars:CosmicLighthousesWithaTwist KatrienKolenberg 481 SpectroscopicResultsFromBlueHillsObservatoryofthe2009–2011EclipseofeAurigae StanleyA.Gorodenski 743 SymbioticStars UlisseMunari 572 TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 UV-Blue(CCD)andHistoric(Photographic)SpectraofeAurigae—Summary R.ElizabethGriffinandRobertE.Stencel 714 VariableStarsandtheAsymptoticGiantBranch:StellarPulsations,DustProduction,andMassLoss AngelaK.Speck 244 VSXJ071108.7+695227:aNewlyDiscoveredShort-periodEclipsingBinary MarioDamasso et al. 945 TheWorld’sStrangestSupernovaMayNotBeaSupernovaAtAll(Abstract) CarolineMoore 421

SPECTROSCOPIC ANALYSIS ClassicalandRecurrentNovae UlisseMunari 582 EclipseSpectropolarimetryoftheeAurigaeSystem KathleenM.Geiseet al. 767 HaSpectralMonitoringofeAurigae2009–2011Eclipse BenjaminMauclaireet al. 718 HowAmateursCanContributetotheFieldofTransitingExoplanets BryceCroll 456 InternationalObservingCampaign:PhotometryandSpectroscopyofPCygni ErnstPollmannandThiloBauer 894 RRLyraeStars:CosmicLighthousesWithaTwist KatrienKolenberg 481 SpectroscopicResultsFromBlueHillsObservatoryofthe2009–2011EclipseofeAurigae StanleyA.Gorodenski 743 UV-Blue(CCD)andHistoric(Photographic)SpectraofeAurigae—Summary R.ElizabethGriffinandRobertE.Stencel 714 VSXJ071108.7+695227:aNewlyDiscoveredShort-periodEclipsingBinary MarioDamasso et al. 945

STANDARD STARS TheAcquisitionofPhotometricData ArloU.Landolt 355 APracticalApproachtoTransformingMagnitudesontoaStandardPhotometricSystem DavidBoyd 990

STATISTICAL ANALYSIS TheAcquisitionofPhotometricData ArloU.Landolt 355

Index, JAAVSO Volume 40, 2012 1103 Algorithms+Observations=VStar DavidBenn 852 AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 AnAmateur-ProfessionalInternationalObservingCampaignfortheEPOXIMission: NewInsightsIntoComets(Abstract) KarenJ.Meech 422 AnAnalysisoftheLong-termPhotometricBehaviorofeAurigae BrianK.Kloppenborg,JeffreyL.Hopkins,andRobertE.Stencel 647 BVRIPhotometryofSN2011feinM101 MichaelW.RichmondandHoraceA.Smith 872 CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 CataclysmicVariablesintheBackyard(Abstract) JosephPatterson 240 TheCitationofManuscriptsWhichHaveAppearedinJAAVSO ArloU.Landolt 1032 TheCitizenSkyPlanetariumTrailer(Posterabstract) RebeccaTurner,AaronPrice,andRyanWyatt 428 ClassicalandRecurrentNovae UlisseMunari 582 ClassicalCepheidsAfter228YearsofStudy DavidG.Turner 502 CollaborativeResearchEffortsforCitizenScientists(Posterabstract) BrianK.Kloppenborget al. 426 dScorpii2011Periastron:VisualandDigitalPhotometricCampaign(Posterabstract) CostantinoSigismondiSapienza 419 ADemonstrationofAccurateWide-fieldV-bandPhotometryUsingaConsumer-gradeDSLRCamera BrianK.Kloppenborget al. 815 EclipseSpectropolarimetryoftheeAurigaeSystem KathleenM.Geiseet al. 767 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 EclipsingBinariesThatDon’tEclipseAnymore:theStrangeCaseoftheOnce (andFuture?)EclipsingBinaryQXCassiopeiae(Abstract) EdwardF.Guinanet al. 417 ExploringtheBreadthandSourcesofVariableStarAstronomers’AstronomyKnowledge: FirstSteps(Abstract) StephanieJ.Slater 427 AGeneralizedLinearMixedModelforEnumeratedSunspots(Abstract) JamieRiggs 436 GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis PierredePonthièreet al. 904 GSC4552-1643:aWUMaSystemWithCompleteEclipses DirkTerrellandJohnGross 941 HaSpectralMonitoringofeAurigae2009–2011Eclipse BenjaminMauclaireet al. 718 HighCadenceMeasurementofNeutralSodiumandPotassiumAbsorptionDuringthe 2009–2011EclipseofeAurigae RobinLeadbeateret al. 729 HighSpeedUBVPhotometryofeAurigae’s2009–2011Eclipse(Posterabstract) AaronPriceet al. 418 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 InternationalObservingCampaign:PhotometryandSpectroscopyofPCygni ErnstPollmannandThiloBauer 894

Index, JAAVSO Volume 40, 20121104 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics JohnR.Percy 230 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 MembershipofthePlanetaryNebulaAbell8intheOpenClusterBica6andImplicationsfor thePNDistanceScale(Posterabstract) DavidG.Turneret al. 423 ModelingtheDiskintheeAurigaeSystem:aBriefReviewWithProposedNumericalSolutions RichardL.PearsonIIIandRobertE.Stencel 802 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 ObservationsUsingaBespokeMediumResolutionFastSpectrograph(Abstract) JohnMenke 1037 PolarimetryofeAurigae,FromNovember2009toJanuary2012 GaryM.Cole 787 APracticalApproachtoTransformingMagnitudesontoaStandardPhotometricSystem DavidBoyd 990 PreliminaryAnalysisofMOSTObservationsoftheTrapezium(Abstract) MatthewR.Templetonet al. 415 ProbingMiraAtmospheresUsingOpticalInterferometricTechniques(Abstract) SamRagland 265 ThePulsationPeriodoftheHotHydrogen-DeficientStarMVSgr JohnR.PercyandRongFu 900 RaschAnalysisofScientificLiteracyinanAstronomicalCitizenScienceProject(Posterabstract) AaronPrice 427 TheRotationalPeriodoftheSunUsingtheDopplerShiftoftheHaSpectralLine(Abstract) RobertM.Gill 1038 RSSagittae:theSearchforEclipses JerryD.Horne 278 SmallTelescopeInfraredPhotometryoftheeAurigaeEclipse ThomasP.Rutherford 704 SolarCycle24—WillItBeUnusuallyQuiet?(Abstract) RodneyHowe 435 Spots,Eclipses,andPulsation:theInterplayofPhotometryandOpticalInterferometric Imaging(Abstract) BrianK.Kloppenborg 266 StatusoftheUSNOInfraredAstrometryProgram(Posterabstract) FrederickJohnVrbaet al. 434 StellarPhotometryWithDSLR:BenchmarkofTwoColorCorrectionTechniquesToward Johnson’sVJandTychoVT RogerPieri 834 AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 ThingsWeDon’tUnderstandAboutRRLyraeStars HoraceA.Smith 327 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222 Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 UV-Blue(CCD)andHistoric(Photographic)SpectraofeAurigae—Summary R.ElizabethGriffinandRobertE.Stencel 714 V-bandLightCurveAnalysisofeAurigaeDuringthe2009–2011Eclipse ThomasKarlsson 668 WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539

Index, JAAVSO Volume 40, 2012 1105 WhatMassLossModelingTellsUsAboutPlanetaryNebulae(Abstract) LeeAnneWillsonandQianWang 424

STRANGE (QUARK) STARS TheHuntfortheQuark-Nova;aCallforObservers(Abstract) DavidJ.Laneet al. 425

SU URSAE MAJORIS STARS [See CATACLYSMIC VARIABLES]

SUDDEN IONOSPHERIC DISTURBANCES SolarCycle24—WillItBeUnusuallyQuiet?(Abstract) RodneyHowe 435

SUN [See SOLAR]

SUNSPOTS, SUNSPOT COUNTS TheEffectofOnlineSunspotDataonVisualSolarObservers KristineLarsen 374 Flares,Fears,andForecasts:PublicMisconceptionsAbouttheSunspotCycle KristineLarsen 407 AGeneralizedLinearMixedModelforEnumeratedSunspots(Abstract) JamieRiggs 436 SolarCycle24—WillItBeUnusuallyQuiet?(Abstract) RodneyHowe 435

SUPERNOVAE [See also VARIABLE STARS (GENERAL)] AAVSOEstimatesandtheNatureofTypeCSemiregulars:ProgenitorsofTypeIISupernovae(Abstract) DavidG.Turneret al. 415 BrightNewType-IaSupernovainthePinwheelGalaxy(M101):PhysicalPropertiesof SN2011feFromPhotometryandSpectroscopy(Posterabstract) SaiGouravajhalaet al. 419 BritishAstronomicalAssociationVariableStarSection,1890–2011 JohnToone 154 BVRIPhotometryofSN2011feinM101 MichaelW.RichmondandHoraceA.Smith 872 ACenturyofSupernovae PeterGarnavich 598 TheHuntfortheQuark-Nova;aCallforObservers(Abstract) DavidJ.Laneet al. 425 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 KingCharles’Star:AMultidisciplinaryApproachtoDatingtheSupernovaKnownas CassiopeiaA(Abstract) MartinLunn 150 Stars,Planets,andtheWeather:ifYouDon’tLikeItWaitFiveBillionYears(Abstract) JeremyJ.Drake 425 SymbioticStars UlisseMunari 572 TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539 TheWorld’sStrangestSupernovaMayNotBeaSupernovaAtAll(Abstract) CarolineMoore 421

Index, JAAVSO Volume 40, 20121106SUSPECTED VARIABLES [See also VARIABLE STARS (GENERAL)] ADemonstrationofAccurateWide-fieldV-bandPhotometryUsingaConsumer-gradeDSLRCamera BrianK.Kloppenborget al. 815 TheRossVariableStarsRevisited.II WayneOsbornandO.FrankMills 929 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222

SYMBIOTIC STARS [See also VARIABLE STARS (GENERAL)] ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 SymbioticStars UlisseMunari 572

T TAURI STARS [See also VARIABLE STARS (GENERAL)] GuidingForcesandJanetA.Mattei ElizabethO.Waagen 65 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 TheVariabilityofYoungStellarObjects WilliamHerbst 448

TERRESTRIAL AnAmateur-ProfessionalInternationalObservingCampaignfortheEPOXIMission: NewInsightsIntoComets(Abstract) KarenJ.Meech 422 Flares,Fears,andForecasts:PublicMisconceptionsAbouttheSunspotCycle KristineLarsen 407 FrankElmoreRossandHisVariableStarDiscoveries WayneOsborn 133 StarWatchingPromotedbytheMinistryoftheEnvironment,Japan SeiichiSakuma 391 Stars,Planets,andtheWeather:ifYouDon’tLikeItWaitFiveBillionYears(Abstract) JeremyJ.Drake 425

UNKNOWN; UNSTUDIED VARIABLES ADemonstrationofAccurateWide-fieldV-bandPhotometryUsingaConsumer-gradeDSLRCamera BrianK.Kloppenborget al. 815 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 TheRossVariableStarsRevisited.II WayneOsbornandO.FrankMills 929 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222

UXORS—UX ORIONIS STARS [See also VARIABLE STARS (GENERAL)] HaEmissionExtractionUsingNarrowbandPhotometricFilters(Abstract) GaryWalker 432 TheVariabilityofYoungStellarObjects WilliamHerbst 448

Index, JAAVSO Volume 40, 2012 1107VARIABLE STAR OBSERVING ORGANIZATIONS AAVSOEstimatesandtheNatureofTypeCSemiregulars:ProgenitorsofTypeIISupernovae(Abstract) DavidG.Turneret al. 415 TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 TheAAVSO2011DemographicandBackgroundSurvey AaronPriceandKevinB.Paxson 1010 TheAAVSOWidow—orShouldWeSaySpouse? ThomasR.Williams 77 AAVSOnet:theRoboticTelescopeNetwork(Posterabstract) MikeSimonsen 432 AboutThis100thAnniversaryIssue JohnR.Percy 1 Algorithms+Observations=VStar DavidBenn 852 AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 AnneS.Young:ProfessorandVariableStarObserverExtraordinaire KatherineBracher 24 Apollo14RoadTrip(Posterabstract) PaulValleli 223 BritishAstronomicalAssociationVariableStarSection,1890–2011 JohnToone 154 CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 CataclysmicVariablesintheBackyard(Abstract) JosephPatterson 240 CentennialHighlightsinAstronomy OwenGingerich 438 TheCitationofManuscriptsWhichHaveAppearedinJAAVSO ArloU.Landolt 1032 ClassicalandRecurrentNovae UlisseMunari 582 CollaborativeResearchEffortsforCitizenScientists(Posterabstract) BrianK.Kloppenborget al. 426 ContributionsbyCitizenScientiststoAstronomy(Abstract) ArneA.Henden 239 DataEvolutioninVSX:MakingaGoodThingBetter(Abstract) SebastianOtero 431 DataRelease3oftheAAVSOAll-SkyPhotometricSurvey(APASS)(Posterabstract) ArneA.Hendenet al. 430 ExploringtheBreadthandSourcesofVariableStarAstronomers’AstronomyKnowledge: FirstSteps(Abstract) StephanieJ.Slater 427 TheGEOSAssociationofVariableStarObservers(Abstract) Franz-JosefHambschet al. 177 GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis PierredePonthièreet al. 904 GuidingForcesandJanetA.Mattei ElizabethO.Waagen 65 HaEmissionExtractionUsingNarrowbandPhotometricFilters(Abstract) GaryWalker 432 HighlightingeAurigaeandCitizenSky JohnR.Percy 609 HistoryofAmateurVariableStarObservationsinJapan(Posterabstract) SeiichiroKiyota 178

Index, JAAVSO Volume 40, 20121108 InternationalObservingCampaign:PhotometryandSpectroscopyofPCygni ErnstPollmannandThiloBauer 894 IntroductiontoBAV(Abstract) Franz-JosefHambschandJoachimHübscher 177 IntroductiontotheHistoryPaperSessions ThomasR.Williams 20 IntroductiontotheJointAAS-AAVSOScientificPaperSessions MatthewR.Templeton 226 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 TheLegacyofAnnieJumpCannon:DiscoveriesandCataloguesofVariableStars(Abstract) BarbaraL.Welther 92 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics JohnR.Percy 230 MargaretW.MayallintheAAVSOArchives(Abstract) MichaelSaladyga 92 Miras LeeAnneWillsonandMassimoMarengo 516 NewLifeforOldData:DigitizationofDataPublishedintheHarvardAnnals(Abstract) MatthewR.Templetonet al. 429 ANoteontheVariabilityofV538Cassiopeiae GustavHolmberg 986 TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 AnOverviewoftheAAVSO’sInformationTechnologyInfrastructureFrom1967to1997 RichardC.S.Kinne 208 PlanetHuntingWithHATNetandHATSouth(Abstract) GasparBakos 241 ProfessionalAstronomersinServicetotheAAVSO(Posterabstract) MichaelSaladygaandElizabethO.Waagen 223 ProgressReportforAdaptingAPASSDataReleasesfortheCalibrationofHarvardPlates EdwardJ.Los 396 TheRASNZPhotometrySection,IncorporatingtheAucklandPhotoelectricObservers’ Group(Posterabstract) StanWalker 177 TheRASNZVariableStarSectionandVariableStarsSouth AlbertJonesandStanWalker 168 RaschAnalysisofScientificLiteracyinanAstronomicalCitizenScienceProject(Posterabstract) AaronPrice 427 ReminiscencesontheCareerofMarthaStahrCarpenter:BetweenaRockand(Several)HardPlaces KristineLarsen 51 ReportFromtheeAurigaeCampaigninGreece GrigorisMaraveliaset al. 679 RRLyraeStars:CosmicLighthousesWithaTwist KatrienKolenberg 481 SolarCycle24—WillItBeUnusuallyQuiet?(Abstract) RodneyHowe 435 StarWatchingPromotedbytheMinistryoftheEnvironment,Japan SeiichiSakuma 391 SymbioticStars UlisseMunari 572 ThingsWeDon’tUnderstandAboutRRLyraeStars HoraceA.Smith 327 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222

Index, JAAVSO Volume 40, 2012 1109 Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 TheVariableStarObservationsofFrankE.Seagrave(Abstract) GeraldP.Dyck 223 VariableStarsandConstantCommitments:theStellarCareerofDorritHoffleit KristineLarsen 44 TheVariableStarsSouthEclipsingBinaryDatabase TomRichards 983 TheVisualEraoftheAAVSOEclipsingBinaryProgram DavidB.Williams,MarvinE.Baldwin,andGerardSamolyk 180 VSX:theNextGeneration(Abstract) ChristopherL.Watson 431 WalkingWithAAVSOGiants—aPersonalJourney(1960s) RogerS.KolmanandMikeSimonsen 189 The“WerkgroepVeranderlijkeSterren”ofBelgium PatrickWilset al. 164 TheWorldScienceFestival(Abstract) JohnPazmino 428 TheZCamPaignEarlyResults(Abstract) MikeSimonsen 241

VARIABLE STAR OBSERVING [See also INSTRUMENTATION] AAVSOEstimatesandtheNatureofTypeCSemiregulars:ProgenitorsofTypeIISupernovae(Abstract) DavidG.Turneret al. 415 TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 TheAAVSO2011DemographicandBackgroundSurvey AaronPriceandKevinB.Paxson 1010 TheAAVSOWidow—orShouldWeSaySpouse? ThomasR.Williams 77 AAVSOnet:theRoboticTelescopeNetwork(Posterabstract) MikeSimonsen 432 TheAcquisitionofPhotometricData ArloU.Landolt 355 AdverseHealthEffectsofNighttimeLighting MarioMotta 380 Algorithms+Observations=VStar DavidBenn 852 AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 AnAppreciationofClintonB.FordandtheAAVSOofFiftyYearsAgo TonyHull 203 AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData(Posterabstract) MarcoCiocca,EthanE.Kilgore,andWestleyW.Williams 433 BritishAstronomicalAssociationVariableStarSection,1890–2011 JohnToone 154 BVRIPhotometryofSN2011feinM101 MichaelW.RichmondandHoraceA.Smith 872 CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 CataclysmicVariablesintheBackyard(Abstract) JosephPatterson 240 ACenturyofSupernovae PeterGarnavich 598 ClassicalandRecurrentNovae UlisseMunari 582

Index, JAAVSO Volume 40, 20121110 CollaborativeResearchEffortsforCitizenScientists(Posterabstract) BrianK.Kloppenborget al. 426 ContributionsbyCitizenScientiststoAstronomy(Abstract) ArneA.Henden 239 DataEvolutioninVSX:MakingaGoodThingBetter(Abstract) SebastianOtero 431 dScorpii2011Periastron:VisualandDigitalPhotometricCampaign(Posterabstract) CostantinoSigismondiSapienza 419 ADemonstrationofAccurateWide-fieldV-bandPhotometryUsingaConsumer-gradeDSLRCamera BrianK.Kloppenborget al. 815 DigitalArchiving:WherethePastLivesAgain KevinB.Paxson 360 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 EclipsingBinariesThatDon’tEclipseAnymore:theStrangeCaseoftheOnce (andFuture?)EclipsingBinaryQXCassiopeiae(Abstract) EdwardF.Guinanet al. 417 TheEffectofOnlineSunspotDataonVisualSolarObservers KristineLarsen 374 EnhancingtheEducationalAstronomicalExperienceofNon-ScienceMajorsWiththe UseofaniPadandTelescope(Abstract) RobertM.GillandMichaelJ.Burin 1037 ExploringtheBreadthandSourcesofVariableStarAstronomers’AstronomyKnowledge: FirstSteps(Abstract) StephanieJ.Slater 427 FastSpectrometerConstructionandTesting(Abstract) JohnMenke 1037 Flares,Fears,andForecasts:PublicMisconceptionsAbouttheSunspotCycle KristineLarsen 407 TheGEOSAssociationofVariableStarObservers(Abstract) Franz-JosefHambschet al. 177 HaEmissionExtractionUsingNarrowbandPhotometricFilters(Abstract) GaryWalker 432 HighlightingeAurigaeandCitizenSky JohnR.Percy 609 TheHistoryofVariableStars:aFreshLook(Abstract) RobertAlanHatch 151 HowAmateursCanContributetotheFieldofTransitingExoplanets BryceCroll 456 Illinois—WhereAstronomicalPhotometryGrewUp BarryB.BeamanandMichaelT.Svec 141 IntensiveObservationsofCataclysmic,RRLyrae,andHighAmplitudedScuti(HADS)VariableStars Franz-JosefHambsch 289 InterferometryandtheCepheidDistanceScale ThomasG.BarnesIII 256 IntroductiontoBAV(Abstract) Franz-JosefHambschandJoachimHübscher 177 IntroductiontotheHistoryPaperSessions ThomasR.Williams 20 IntroductiontotheJointAAS-AAVSOScientificPaperSessions MatthewR.Templeton 226 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239

Index, JAAVSO Volume 40, 2012 1111 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics JohnR.Percy 230 Miras LeeAnneWillsonandMassimoMarengo 516 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 ObservationsUsingaBespokeMediumResolutionFastSpectrograph(Abstract) JohnMenke 1037 TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 PlanetHuntingWithHATNetandHATSouth(Abstract) GasparBakos 241 PolarimetryofeAurigae,FromNovember2009toJanuary2012 GaryM.Cole 787 APracticalApproachtoTransformingMagnitudesontoaStandardPhotometricSystem DavidBoyd 990 PreliminaryAnalysisofMOSTObservationsoftheTrapezium(Abstract) MatthewR.Templetonet al. 415 TheRASNZPhotometrySection,IncorporatingtheAucklandPhotoelectricObservers’ Group(Posterabstract) StanWalker 177 TheRASNZVariableStarSectionandVariableStarsSouth AlbertJonesandStanWalker 168 ReminiscencesontheCareerofMarthaStahrCarpenter:BetweenaRockand(Several)HardPlaces KristineLarsen 51 ReportFromtheeAurigaeCampaigninGreece GrigorisMaraveliaset al. 679 ROAD(RemoteObservatoryAtacamaDesert):IntensiveObservationsofVariableStars Franz-JosefHambsch 1003 TheRotationalPeriodoftheSunUsingtheDopplerShiftoftheHaSpectralLine(Abstract) RobertM.Gill 1038 ASingleBeamPolarimeter(Posterabstract) JerryD.Horne 1038 SmallTelescopeInfraredPhotometryoftheeAurigaeEclipse ThomasP.Rutherford 704 SpectroscopicResultsFromBlueHillsObservatoryofthe2009–2011EclipseofeAurigae StanleyA.Gorodenski 743 Spots,Eclipses,andPulsation:theInterplayofPhotometryandOpticalInterferometric Imaging(Abstract) BrianK.Kloppenborg 266 StarWatchingPromotedbytheMinistryoftheEnvironment,Japan SeiichiSakuma 391 StatusoftheUSNOInfraredAstrometryProgram(Posterabstract) FrederickJohnVrbaet al. 434 StellarPhotometryWithDSLR:BenchmarkofTwoColorCorrectionTechniquesToward Johnson’sVJandTychoVT RogerPieri 834 SymbioticStars UlisseMunari 572 Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds DouglasL.Welch 492 TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 TheVariabilityofYoungStellarObjects WilliamHerbst 448 VariableStarObserversIHaveKnown CharlesE.Scovil 196

Index, JAAVSO Volume 40, 20121112 VariableStarObservingWiththeBradfordRoboticTelescope(Abstract) RichardC.S.Kinne 435 TheVisualEraoftheAAVSOEclipsingBinaryProgram DavidB.Williams,MarvinE.Baldwin,andGerardSamolyk 180 VSX:theNextGeneration(Abstract) ChristopherL.Watson 431 WalkingWithAAVSOGiants—aPersonalJourney(1960s) RogerS.KolmanandMikeSimonsen 189 The“WerkgroepVeranderlijkeSterren”ofBelgium PatrickWilset al. 164 WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539 TheWorldScienceFestival(Abstract) JohnPazmino 428 TheZCamPaignEarlyResults(Abstract) MikeSimonsen 241

VARIABLE STARS (GENERAL) AAVSOEstimatesandtheNatureofTypeCSemiregulars:ProgenitorsofTypeIISupernovae(Abstract) DavidG.Turneret al. 415 TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 AAVSOnet:theRoboticTelescopeNetwork(Posterabstract) MikeSimonsen 432 AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 AnAnalysisoftheLong-termPhotometricBehaviorofeAurigae BrianK.Kloppenborg,JeffreyL.Hopkins,andRobertE.Stencel 647 CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 CataclysmicVariablesintheBackyard(Abstract) JosephPatterson 240 CentennialHighlightsinAstronomy OwenGingerich 438 ACenturyofSupernovae PeterGarnavich 598 ClassicalandRecurrentNovae UlisseMunari 582 ClassicalCepheidsAfter228YearsofStudy DavidG.Turner 502 CollaborativeResearchEffortsforCitizenScientists(Posterabstract) BrianK.Kloppenborget al. 426 ContributionsbyCitizenScientiststoAstronomy(Abstract) ArneA.Henden 239 DataEvolutioninVSX:MakingaGoodThingBetter(Abstract) SebastianOtero 431 DataRelease3oftheAAVSOAll-SkyPhotometricSurvey(APASS)(Posterabstract) ArneA.Hendenet al. 430 TheDevelopmentofEarlyPulsationTheory,or,HowCepheidsAreLikeSteamEngines MatthewStanley 100 DigitalArchiving:WherethePastLivesAgain KevinB.Paxson 360 EclipseSpectropolarimetryoftheeAurigaeSystem KathleenM.Geiseet al. 767 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467

Index, JAAVSO Volume 40, 2012 1113 EclipsingBinariesThatDon’tEclipseAnymore:theStrangeCaseoftheOnce (andFuture?)EclipsingBinaryQXCassiopeiae(Abstract) EdwardF.Guinanet al. 417 FrankElmoreRossandHisVariableStarDiscoveries WayneOsborn 133 AGeneralizedLinearMixedModelforEnumeratedSunspots(Abstract) JamieRiggs 436 HighSchoolStudentsWatchingStarsEvolve(Abstract) JohnR.Percyet al. 416 HighlightingeAurigaeandCitizenSky JohnR.Percy 609 TheHistoryofVariableStars:aFreshLook(Abstract) RobertAlanHatch 151 HowAmateursCanContributetotheFieldofTransitingExoplanets BryceCroll 456 TheHuntfortheQuark-Nova;aCallforObservers(Abstract) DavidJ.Laneet al. 425 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 InterferometryandtheCepheidDistanceScale ThomasG.BarnesIII 256 IntroductiontotheJointAAS-AAVSOScientificPaperSessions MatthewR.Templeton 226 Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 KingCharles’Star:AMultidisciplinaryApproachtoDatingtheSupernovaKnownas CassiopeiaA(Abstract) MartinLunn 150 TheLegacyofAnnieJumpCannon:DiscoveriesandCataloguesofVariableStars(Abstract) BarbaraL.Welther 92 LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239 Long-TermVisualLightCurvesandtheRoleofVisualObservationsinModernAstrophysics JohnR.Percy 230 MembershipofthePlanetaryNebulaAbell8intheOpenClusterBica6andImplicationsfor thePNDistanceScale(Posterabstract) DavidG.Turneret al. 423 Miras LeeAnneWillsonandMassimoMarengo 516 ModelingtheDiskintheeAurigaeSystem:aBriefReviewWithProposedNumericalSolutions RichardL.PearsonIIIandRobertE.Stencel 802 NewLifeforOldData:DigitizationofDataPublishedintheHarvardAnnals(Abstract) MatthewR.Templetonet al. 429 Non-MiraPulsatingRedGiantsandSupergiants LászlóL.KissandJohnR.Percy 528 PlanetHuntingWithHATNetandHATSouth(Abstract) GasparBakos 241 PreliminaryAnalysisofMOSTObservationsoftheTrapezium(Abstract) MatthewR.Templetonet al. 415 ProbingMiraAtmospheresUsingOpticalInterferometricTechniques(Abstract) SamRagland 265 RRLyraeStars:CosmicLighthousesWithaTwist KatrienKolenberg 481 SolarCycle24—WillItBeUnusuallyQuiet?(Abstract) RodneyHowe 435

Index, JAAVSO Volume 40, 20121114

VARIABLE STARS (INDIVIDUAL); OBSERVING TARGETS [ZAnd]SymbioticStars UlisseMunari 572 [IWAnd]Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 [PXAnd]AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 [V455And]Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 [SAps]WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539 [RAqr]SymbioticStars UlisseMunari 572

Spots,Eclipses,andPulsation:theInterplayofPhotometryandOpticalInterferometric Imaging(Abstract) BrianK.Kloppenborg 266 Stars,Planets,andtheWeather:ifYouDon’tLikeItWaitFiveBillionYears(Abstract) JeremyJ.Drake 425 StatusoftheUSNOInfraredAstrometryProgram(Posterabstract) FrederickJohnVrbaet al. 434 StellarPhotometryWithDSLR:BenchmarkofTwoColorCorrectionTechniquesToward Johnson’sVJandTychoVT RogerPieri 834 StellarPulsationTheoryFromArthurStanleyEddingtontoToday(Abstract) StevenD.KawalerandCarlJ.Hansen 150 AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 SymbioticStars UlisseMunari 572 ThingsWeDon’tUnderstandAboutRRLyraeStars HoraceA.Smith 327 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222 Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds DouglasL.Welch 492 TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 VariableStarsandConstantCommitments:theStellarCareerofDorritHoffleit KristineLarsen 44 VariableStarsandtheAsymptoticGiantBranch:StellarPulsations,DustProduction,andMassLoss AngelaK.Speck 244 TheVariableStarsSouthEclipsingBinaryDatabase TomRichards 983 VSX:theNextGeneration(Abstract) ChristopherL.Watson 431 WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539 WhatMassLossModelingTellsUsAboutPlanetaryNebulae(Abstract) LeeAnneWillsonandQianWang 424 TheWorld’sStrangestSupernovaMayNotBeaSupernovaAtAll(Abstract) CarolineMoore 421 TheZCamPaignEarlyResults(Abstract) MikeSimonsen 241

Index, JAAVSO Volume 40, 2012 1115 [UUAqr]AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 [V605Aql]WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539 [V1315Aql]AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 [V1413Aql]SymbioticStars UlisseMunari 572 [hAql]JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 [RAra]EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 [RZAri]TheAAVSOPhotoelectricPhotometryPrograminItsScientificandSocio-HistoricContext JohnR.Percy 109 [SVAri]ROAD(RemoteObservatoryAtacamaDesert):IntensiveObservationsofVariableStars Franz-JosefHambsch 1003 [TTAri]AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 [UVAur]SymbioticStars UlisseMunari 572 [GVAur]Algorithms+Observations=VStar DavidBenn 852 [IUAur]EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 [NUAur]IntensiveObservationsofCataclysmic,RRLyrae,andHighAmplitudedScuti (HADS)VariableStars Franz-JosefHambsch 289 [NUAur]GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis PierredePonthièreet al. 904 [V363Aur=Lanning10]AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 [eAur]Algorithms+Observations=VStar DavidBenn 852 [eAur]AnAnalysisoftheLong-termPhotometricBehaviorofeAurigae BrianK.Kloppenborg,JeffreyL.Hopkins,andRobertE.Stencel 647 [eAur]AnArtist’sNoteonArtinScience NicoCamargo 867 [eAur]TheCitizenSkyPlanetariumTrailer(Posterabstract) RebeccaTurner,AaronPrice,andRyanWyatt 428 [eAur]EclipseSpectropolarimetryoftheeAurigaeSystem KathleenM.Geiseet al. 767 [eAur]eAurigae—anOverviewofthe2009–2011EclipseCampaignResults RobertE.Stencel 618 [eAur]HaSpectralMonitoringofeAurigae2009–2011Eclipse BenjaminMauclaireet al. 718 [eAur]HighCadenceMeasurementofNeutralSodiumandPotassiumAbsorptionDuringthe 2009–2011EclipseofeAurigae RobinLeadbeateret al. 729 [eAur]HighSpeedUBVPhotometryofeAurigae’s2009–2011Eclipse(Posterabstract) AaronPriceet al. 418 [eAur]HighlightingeAurigaeandCitizenSky JohnR.Percy 609 [eAur]TheInternationaleAurigaeCampaign2009PhotometryReport JeffreyL.Hopkins 633 [eAur]LessonsLearnedDuringtheRecenteAurigaeEclipseObservingCampaign(Abstract) RobertE.Stencel 239

Index, JAAVSO Volume 40, 20121116 [eAur]ModelingtheDiskintheeAurigaeSystem:aBriefReviewWithProposed NumericalSolutions RichardL.PearsonIIIandRobertE.Stencel 802 [eAur]TheOriginsandFutureoftheCitizenSkyProject AaronPriceet al. 614 [eAur]PhotoelectricPhotometryofeAurigaeDuringthe2009–2011EclipseSeason FrankJ.Melillo 695 [eAur]PolarimetryofeAurigae,FromNovember2009toJanuary2012 GaryM.Cole 787 [eAur]ReportFromtheeAurigaeCampaigninGreece GrigorisMaraveliaset al. 679 [eAur]SmallTelescopeInfraredPhotometryoftheeAurigaeEclipse ThomasP.Rutherford 704 [eAur]SpectroscopicResultsFromBlueHillsObservatoryofthe2009–2011EclipseofeAurigae StanleyA.Gorodenski 743 [eAur]StellarPhotometryWithDSLR:BenchmarkofTwoColorCorrectionTechniques TowardJohnson’sVJandTychoVT RogerPieri 834 [eAur]UV-Blue(CCD)andHistoric(Photographic)SpectraofeAurigae—Summary R.ElizabethGriffinandRobertE.Stencel 714 [eAur]V-bandLightCurveAnalysisofeAurigaeDuringthe2009–2011Eclipse ThomasKarlsson 668 [UUBoo]AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData (Posterabstract) MarcoCiocca,EthanE.Kilgore,andWestleyW.Williams 433 [UZBoo]AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 [ZCam]AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 [ZCam]Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 [ACCnc]AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 [OYCar]AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 [IXCas]Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds DouglasL.Welch 492 [QXCas]EclipsingBinariesThatDon’tEclipseAnymore:theStrangeCaseoftheOnce (andFuture?)EclipsingBinaryQXCassiopeiae(Abstract) EdwardF.Guinanet al. 417 [QXCas]EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 [V513Cas]Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 [V538Cas]ANoteontheVariabilityofV538Cassiopeiae GustavHolmberg 986 [CasA]KingCharles’Star:AMultidisciplinaryApproachtoDatingtheSupernova KnownasCassiopeiaA(Abstract) MartinLunn 150 [VarCas06=VSXJ000921.8+543943]APracticalApproachtoTransformingMagnitudes ontoaStandardPhotometricSystem DavidBoyd 990 [V685Cen]EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 [UCep]EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467

Index, JAAVSO Volume 40, 2012 1117 [VVCep]EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 [AHCep]EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 [EECep]APracticalApproachtoTransformingMagnitudesontoaStandardPhotometricSystem DavidBoyd 990 [dCep]JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 [oCet]TheHistoryofVariableStars:aFreshLook(Abstract) RobertAlanHatch 151 [ZCha]AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 [ALCom]Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 [RCrB]JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 [RCrB]WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539 [TCrB]SymbioticStars UlisseMunari 572 [VYCrB]GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis PierredePonthièreet al. 904 [ZCyg]ThingsWeDon’tUnderstandAboutRRLyraeStars HoraceA.Smith 327 [SSCyg]AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 [SSCyg]CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 [SSCyg]ClassicalandRecurrentNovae UlisseMunari 582 [SSCyg]Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 [XXCyg]AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData (Posterabstract) MarcoCiocca,EthanE.Kilgore,andWestleyW.Williams 433 [XZCyg]ThingsWeDon’tUnderstandAboutRRLyraeStars HoraceA.Smith 327 [BFCyg]SymbioticStars UlisseMunari 572 [CICyg]SymbioticStars UlisseMunari 572 [EMCyg]AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 [V407Cyg]SymbioticStars UlisseMunari 572 [V699Cyg]EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 [V1016Cyg]SymbioticStars UlisseMunari 572 [V1500Cyg]ClassicalandRecurrentNovae UlisseMunari 582 [V1776Cyg]AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 [V2467Cyg]ClassicalandRecurrentNovae UlisseMunari 582

Index, JAAVSO Volume 40, 20121118 [V2468Cyg]ClassicalandRecurrentNovae UlisseMunari 582 [PCyg]InternationalObservingCampaign:PhotometryandSpectroscopyofPCygni ErnstPollmannandThiloBauer 894 [TXDel]Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds DouglasL.Welch 492 [LTDel]SymbioticStars UlisseMunari 572 [MQDra(SDSS1553+55)]Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 [EFEri]Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 [UGem]CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 [UGem]Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 [SVGem]EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 [MPGem]IsMPGeminorumanEclipsingBinaryWithaVeryLongPeriod? DietmarBöhme 973 [RSGru]ThePulsationalBehavioroftheHighAmplitudedScutiStarRSGruis JaimeRubénGarcía 272 [AMHer]CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 [DYHer]AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData (Posterabstract) MarcoCiocca,EthanE.Kilgore,andWestleyW.Williams 433 [V838Her]ClassicalandRecurrentNovae UlisseMunari 582 [HSHya]EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 [VWHyi]ROAD(RemoteObservatoryAtacamaDesert):IntensiveObservationsofVariableStars Franz-JosefHambsch 1003 [WXHyi]AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 [CDInd]IntensiveObservationsofCataclysmic,RRLyrae,andHighAmplitudedScuti (HADS)VariableStars Franz-JosefHambsch 289 [SSLac]EclipsingBinariesThatDon’tEclipseAnymore:theStrangeCaseoftheOnce (andFuture?)EclipsingBinaryQXCassiopeiae(Abstract) EdwardF.Guinanet al. 417 [SSLac]EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 [GWLib]Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 [EXLup]TheVariabilityofYoungStellarObjects WilliamHerbst 448 [BHLyn]AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 [BPLyn]AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 [CXLyr]GEOSRRLyraeSurvey:BlazhkoPeriodMeasurementofThreeRRabStars— CXLyrae,NUAurigae,andVYCoronaeBorealis PierredePonthièreet al. 904 [CXLyr]ThingsWeDon’tUnderstandAboutRRLyraeStars HoraceA.Smith 327

Index, JAAVSO Volume 40, 2012 1119 [RRLyr]RRLyraeStars:CosmicLighthousesWithaTwist KatrienKolenberg 481 [bLyr]JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 [bLyr]EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 [TUMen]AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 [BTMon]AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 [V838Mon]ClassicalandRecurrentNovae UlisseMunari 582 [AYMus]EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 [RSOph]SymbioticStars UlisseMunari 572 [V2672Oph]ClassicalandRecurrentNovae UlisseMunari 582 [V1159Ori]Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 [V1820Ori]ROAD(RemoteObservatoryAtacamaDesert):IntensiveObservationsofVariableStars Franz-JosefHambsch 1003 [q1Ori(A,B,C,D)]PreliminaryAnalysisofMOSTObservationsoftheTrapezium(Abstract) MatthewR.Templetonet al. 415 [AGPeg]SymbioticStars UlisseMunari 572 [AUPeg]Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds DouglasL.Welch 492 [51Pegb]HowAmateursCanContributetotheFieldofTransitingExoplanets BryceCroll 456 [RWPer]EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 [GKPer]ClassicalandRecurrentNovae UlisseMunari 582 [GKPer]Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 [V718Per]TheVariabilityofYoungStellarObjects WilliamHerbst 448 [bPer]EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 [bPer]JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 [STPup]Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds DouglasL.Welch 492 [VSge]AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 [RSSge]RSSagittae:theSearchforEclipses JerryD.Horne 278 [WZSge]AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 [FGSge]WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539 [HMSge]SymbioticStars UlisseMunari 572 [RYSgr]Long-TermVisualLightCurvesandtheRoleofVisualObservationsin ModernAstrophysics JohnR.Percy 230

Index, JAAVSO Volume 40, 20121120 [RYSgr]WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539 [MVSgr]ThePulsationPeriodoftheHotHydrogen-DeficientStarMVSgr JohnR.PercyandRongFu 900 [V4334Sgr]ClassicalandRecurrentNovae UlisseMunari 582 [mSgr]EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 [USco]ClassicalandRecurrentNovae UlisseMunari 582 [V907Sco]EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 [dSco]dScorpii2011Periastron:VisualandDigitalPhotometricCampaign(Posterabstract) CostantinoSigismondiSapienza 419 [BWScl]IntensiveObservationsofCataclysmic,RRLyrae,andHighAmplitudedScuti (HADS)VariableStars Franz-JosefHambsch 289 [BWScl]ROAD(RemoteObservatoryAtacamaDesert):IntensiveObservationsofVariableStars Franz-JosefHambsch 1003 [RSct]JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 [V476Sct]ClassicalandRecurrentNovae UlisseMunari 582 [V477Sct]ClassicalandRecurrentNovae UlisseMunari 582 [RTSer]NewLightCurveforthe1909OutburstofRTSerpentis GrantLuberdaandWayneOsborn 887 [FGSer]SymbioticStars UlisseMunari 572 [LXSer]AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 [SWSex]AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 [TTau]TheVariabilityofYoungStellarObjects WilliamHerbst 448 [RRTau]HaEmissionExtractionUsingNarrowbandPhotometricFilters(Abstract) GaryWalker 432 [AATau]TheVariabilityofYoungStellarObjects WilliamHerbst 448 [RWTri]AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 [SUUMa]AmateurObservingPatternsandTheirPotentialImpactonVariableStarScience MatthewR.Templeton 348 [DWUMa]AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 [3SMCstars]WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539 [23LMCstars]WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539 [27variablestars(Tychoidentifications)]ADemonstrationofAccurateWide-field V-bandPhotometryUsingaConsumer-gradeDSLRCamera BrianK.Kloppenborget al. 815 [55RRLyraestars]RecentMaximaof55ShortPeriodPulsatingStars GerardSamolyk 923 [74MilkyWayRCBstars]WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539

Index, JAAVSO Volume 40, 2012 1121 [150EclipsingBinarystars]RecentMinimaof150EclipsingBinaryStars GerardSamolyk 975 [190Rossvariablestars]TheRossVariableStarsRevisited.II WayneOsbornandO.FrankMills 929 [1RXSJ064434.5+334451]AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 [2MASSJ03145502+5618172]Algorithms+Observations=VStar DavidBenn 852 [Abell8]MembershipofthePlanetaryNebulaAbell8intheOpenClusterBica6(Posterabstract) DavidG.Turneret al. 423 [Algol]EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 [Algol]JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 [BD-21.3873]SymbioticStars UlisseMunari 572 [Bica6]MembershipofthePlanetaryNebulaAbell8intheOpenClusterBica6(Posterabstract) DavidG.Turneret al. 423 [CHS7797]TheVariabilityofYoungStellarObjects WilliamHerbst 448 [Comet103P/Hartley2]AnAmateur-ProfessionalInternationalObservingCampaignforthe EPOXIMission:NewInsightsIntoComets(Abstract) KarenJ.Meech 422 [GSC0762-0110]IntensiveObservationsofCataclysmic,RRLyrae,andHighAmplitude dScuti(HADS)VariableStars Franz-JosefHambsch 289 [GSC4552-1643]GSC4552-1643:aWUMaSystemWithCompleteEclipses DirkTerrellandJohnGross 941 [HD17156b]HowAmateursCanContributetotheFieldofTransitingExoplanets BryceCroll 456 [HD80606b]HowAmateursCanContributetotheFieldofTransitingExoplanets BryceCroll 456 [He1-36]SymbioticStars UlisseMunari 572 [HS0129+2933=TTTri]AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 [HS0220+0603]AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 [HS0455+8315]AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 [HS0728+6738]AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 [KH15D]TheVariabilityofYoungStellarObjects WilliamHerbst 448 [Lanning10=V363Aur]AStudyoftheOrbitalPeriodsofDeeplyEclipsingSWSextantisStars DavidBoyd 295 [M64]JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 [Mercury]JohnGoodricke,EdwardPigott,andTheirStudyofVariableStars LindaM.French 120 [MinorPlanet1026Ingrid]LightCurveofMinorPlanet1026Ingrid(Posterabstract) ShelbyDelos,GaryAhrendts,andTimothyBaker 423 [NSV1436(Ross4)]FrankElmoreRossandHisVariableStarDiscoveries WayneOsborn 133 [NSVS5222076]SecularVariationoftheModeAmplitude-RatiooftheDouble-Mode RRLyraeStarNSVS5222076,Part2 DavidA.HurdisandTomKrajci 268

Index, JAAVSO Volume 40, 20121122 [NSVS5222076]ThingsWeDon’tUnderstandAboutRRLyraeStars HoraceA.Smith 327 [NSVS7606408]VariabilityTypeDeterminationandHighPrecisionEphemerisforNSVS7606408 RiccardoFurgoni 955 [R148]TheRossVariableStarsRevisited.II WayneOsbornandO.FrankMills 929 [Ross4(NSV1436)]FrankElmoreRossandHisVariableStarDiscoveries WayneOsborn 133 [SA61]AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData (Posterabstract) MarcoCiocca,EthanE.Kilgore,andWestleyW.Williams 433 [Sakurai’sObject]WhatAretheRCoronaeBorealisStars? GeoffreyC.Clayton 539 [SDSS1324+03]Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 [SDSS1553+55(MQDra)]Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 [SDSSJ0155+00]Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 [SN1972E]TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 [SN1980N]TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 [SN1981B]TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 [SN1981D]TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 [SN1983R]TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 [SN1986G]TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 [SN1987A]ACenturyofSupernovae PeterGarnavich 598 [SN1998bu]TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 [SN1999cl]TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 [SN1999ee]TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 [SN1999em]TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 [SN2001el]TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 [SN2002cv]TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 [SN2003cq]TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 [SN2003gs]TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 [SN2003hn]TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 [SN2003hv]TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 [SN2004S]TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 [SN2006X]TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334

Index, JAAVSO Volume 40, 2012 1123

VIDEO AutomationofEasternKentuckyUniversityObservatoryandPreliminaryData(Posterabstract) MarcoCiocca,EthanE.Kilgore,andWestleyW.Williams 433 TheCitizenSkyPlanetariumTrailer(Posterabstract) RebeccaTurner,AaronPrice,andRyanWyatt 428

VISION, PHYSIOLOGY OF AdverseHealthEffectsofNighttimeLighting MarioMotta 380 TheEffectofOnlineSunspotDataonVisualSolarObservers KristineLarsen 374

VISUAL MAGNITUDE (mv) BVRIPhotometryofSN2011feinM101 MichaelW.RichmondandHoraceA.Smith 872 ADemonstrationofAccurateWide-fieldV-bandPhotometryUsingaConsumer-gradeDSLRCamera BrianK.Kloppenborget al. 815 StellarPhotometryWithDSLR:BenchmarkofTwoColorCorrectionTechniquesToward Johnson’sVJandTychoVT RogerPieri 834

WHITE DWARFS CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563 SymbioticStars UlisseMunari 572 Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94

X-RAY SOURCES CataclysmicVariables PaulaSzkodyandBorisT.Gaensicke 563

[SN2008ha]TheWorld’sStrangestSupernovaMayNotBeaSupernovaAtAll(Abstract) CarolineMoore 421 [SN2009dc]TheUsefulnessofTypeIaSupernovaeforCosmology—aPersonalReview KevinKrisciunas 334 [SN2011fe]BrightNewType-IaSupernovainthePinwheelGalaxy(M101): PhysicalPropertiesofSN2011feFromPhotometryandSpectroscopy(Posterabstract) SaiGouravajhalaet al. 419 [SN2011fe]BVRIPhotometryofSN2011feinM101 MichaelW.RichmondandHoraceA.Smith 872 [Sun]TheEffectofOnlineSunspotDataonVisualSolarObservers KristineLarsen 374 [TYC1031012621]Type2CepheidsintheMilkyWayGalaxyandtheMagellanicClouds DouglasL.Welch 492 [V79inM3]SecularVariationoftheModeAmplitude-RatiooftheDouble-Mode RRLyraeStarNSVS5222076,Part2 DavidA.HurdisandTomKrajci 268 [VSXJ000921.8+543943(VarCas06)]APracticalApproachtoTransformingMagnitudes ontoaStandardPhotometricSystem DavidBoyd 990 [VSXJ071108.7+695227]VSXJ071108.7+695227:aNewlyDiscoveredShort-period EclipsingBinary MarioDamasso,et al. 945 [WASP12b]HowAmateursCanContributetotheFieldofTransitingExoplanets BryceCroll 456

Index, JAAVSO Volume 40, 20121124 CataclysmicVariablesintheBackyard(Abstract) JosephPatterson 240 ACenturyofSupernovae PeterGarnavich 598 ClassicalandRecurrentNovae UlisseMunari 582 ClassicalCepheidsAfter228YearsofStudy DavidG.Turner 502 EclipsingBinariesinthe21stCentury—OpportunitiesforAmateurAstronomers EdwardF.Guinan,ScottG.Engle,andEdwardJ.Devinney 467 ImagingVariableStarsWithHST(Abstract) MargaritaKarovska 265 Stars,Planets,andtheWeather:ifYouDon’tLikeItWaitFiveBillionYears(Abstract) JeremyJ.Drake 425 20MillionObservations:theAAVSOInternationalDatabaseandItsFirstCentury(Posterabstract) ElizabethO.Waagen 222 Twenty-EightYearsofCVResultsWiththeAAVSO PaulaSzkodyet al. 94 TheVariabilityofYoungStellarObjects WilliamHerbst 448

YSO—YOUNG STELLAR OBJECTS Introduction:VariableStarAstronomyinthe21stCentury JohnR.Percy 442 TheVariabilityofYoungStellarObjects WilliamHerbst 448

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