First results from the Loss of the Night app
Christopher Kyba, Annette Krop-Benesch, Franz HölkerFreie Universität Berlin / IGB
13th European Symposium 2013Pamplona, Spain
September 14, 2013
Background: GLOBE at Night
NELM
Kyba et al.Sci Rep (2013)
Problems with GaN• Can’t identify constellations in the
city• Δm is fairly large for individual
observations (~1.2 mag)• Atmospheric correction?
Solution: Verlust der Nacht app!
• Part of BMBF Wissen-schafts Jahr 2012
• Programmed by Cosalux
• Based upon Google Sky program
• Lots of information about artificial light at night inside app
Star selection
• From 10o to 45o from zenith
• Mag<5.2• Only ~1000
stars already in Google app
Star selection: Stage 1
Is star found?
Start: Identify brightest star in sky (mnew)
Assign user new star with
mnew
Identify new star in range
m+0.5<mnew<m+1
Yes
Proceed toStage 2
No
Star selection: Stage 2
New star:10% brighter
70% slightly fainter20% much fainter
Yes
NoIdentify much brighter star
m-1.5<mnew<m-0.5
Assign user star with mnew
Is star found?
New star:50% much brighter
40% slightly brighter
10% slightly fainter
Unsure
Example Data
1
2
3
4
5
Stel
lar m
agni
tude
Time (minutes)0
Dresden observations
1
2
3
4
5
Stel
lar m
agni
tude
Time (minutes)
not visible
0
Dresden observations
1
2
3
4
5
Stel
lar m
agni
tude
Time (minutes)
not visiblenot sure
0
Cinzano ~4.66Fit ~4.0 (0.9)
Global app usage
Data submission over time
April June August
1000
200
Data submission over time
April June August
Good
obs
erva
tion
%
0
50
100
• Faintest stars in app have mag ~5• App is only designed for urban
astronomy!
Problem: Not enough urban data
Problem: Not enough urban data
Cinzano pop>9bn– Germany: 25%– Greece: 47%– Japan: 63%– Spain: 57%– USA: 62%– EU: 38%
Cinzano pop>27bn– Germany: 0%– Greece: 17%– Japan: 27%– Spain: 25%– USA: 30%– EU: 8%
NELM<4NELM<4.8
App users: 21%GaN: 32%
App users: 2%GaN: 6%
Which stars are best?
Megrez (HR 4660)– mag 3.31– 20 seconds– Found 91%– Unsure 3%– Easier star
Edasich (HR 5744)– mag 3.29– 31 seconds– Found 66%– Unsure 18%– Harder star
Big Dipper Draco
• Need more urban users!• Expansion to 10 languages• Loss of the Night blog:
www.lossofthenight.blogspot.com• Search for additional funding
Going forward
Acknowledgements
Title illustration: Light pollution It’s not pretty: Jeremy Stanley (Wikimedia Commons)
The app and our project is funded through:Verlust der Nacht
German Ministry of Education and ResearchBMBF-033L038A
Thanks to Google for making Sky Map source code available, to GLOBE at Night for
consulting in the app development, and to app testers!
Urban park in Berlin
1
2
3
4
5
Stel
lar m
agni
tude
Time (minutes)
not visiblenot sure
Maximum likelihood fitPr
obab
ility
531 NELM
1
0
Maximum likelihood fitPr
obab
ility
531 NELM
1
0
Citizen Science Works!
Observed sky brightness
Sternenhimmel
100x Sternenhimmel
Sky
brig
htne
ss
Top Related