Precise wavelengthreference for Spirou

F. Pepe, F. Wildi, B. Chazelas, C. Lovis, S. Udry

The wavelength calibration

px

λi ref

xi

λx

Thorium lines

Achieved Δλλ: (Absolute) accuracy: 5 x 10-8

Scale factor: 3 x 10-8 Repeatability: 6 x 10-10 (= 20 cms-1)

The perfect calibrator

Cover full spectral range

Constant line spacing

Lines width < spectrograph resolution

High density of lines, up to one per ~2-3 SE

All wavelengths precisely known and stable

Homogeneous line intensities, high ‘brightness’

Fabry-Pérot or Laser frequency comb

The perfect calibrator

HARPS FPCS System

Vacuum control

Temperature control

Light source

HARPS Fabry-Pérot Assembly

Fabry-Pérot at La Silla

Calibration Unit

FPCS Spectrum with HARPS

FPCS Specifications

FPCS short-term RV-stability

Time series of 7 hours

FPCS long-term RV-stability

Nightly calibration over 80 nights

New-generation FPCS

Mechanics instead of glass work (maintenance)

New white light source (reliability and costs)

Mirrors instead of lenses (wide range, IR) for collimator and camera

Optimize etalon for stability and throughput over the specified spectral range

Etc.

Spirou FPCS configurationSupercontinuum laser or LDLS (laser-driven Xe)

Fiber-link from source to vacuum vessel

Vacuum vessel (fiber in- and output)

Thermal control

FPCS opto-mechanics (support and mirrors)

FP etalon

Fiber from vacuum vessel to calibration unit

Interface: Standard FC or SMA fiber connector (Etendue TBD)

LDLS light source

Up to 2400 nm !(like 10’000 K BB)

New opto-mechanics design (in progress)

Spirou FPCS capital cost

Light source: 25’000 EUR

FP etalon: 20’000 EUR

Vacuum vessel: 10’000 EUR

Vacuum gauges and control: 15’000 EUR (TBC)

FPCS opto-mechanics: 25’000 EUR

Thermal control: 5’000 EUR

Fibers: 2’000 EUR

Total: 102’000 EUR (TBC)

Spirou FPCS manpower costs

Requirements definition: 0.1 FTE

Design optimization: 0.3 FTE

Procurement of components: 0.2 FTE

Opto-mechanics manufacturing: 0.5 FTE

Assembling and adjusting: 0.2 FTE

Testing and tuning: 0.2 FTE

Total: 1.5 FTE (TBC)

Spirou FPCS travel costs

Roughly 10’000 EUR per phase (depends strongly on number of meetings and reviews)

Total: 40’000 EUR (TBC)

Does not include participation to (other) workgroups