Rubidium-traced white-light etalon calibrator for radial velocity measurements at the cm s-1 level

Julian Stürmer*, Andreas Seifahrt, Christian Schwab, Jacob L. Bean

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


We report on the construction and testing of a vacuum-gap Fabry-Pérot etalon calibrator for high precision radial velocity spectrographs. Our etalon is traced against a rubidium frequency standard to provide a cost effective, yet ultra precise wavelength reference. We describe here a turn-key system working at 500 to 900 nm, ready to be installed at any current and next-generation radial velocity spectrograph that requires calibration over a wide spectral bandpass. Where appropriate, we have used off-the-shelf, commercial components with demonstrated long-term performance to accelerate the development timescale of this instrument. Our system combines for the first time the advantages of passively stabilized etalons for optical and near-infrared wavelengths with the laser-locking technique demonstrated for single-mode fiber etalons. We realize uncertainties in the position of one etalon line at the 10cm s-1 level in individual measurements taken at 4 Hz. When binning the data over 10 s, we are able to trace the etalon line with a precision of better than 3cm s-1. We present data obtained during a week of continuous operation where we detect (and correct for) the predicted, but previously unobserved shrinking of the etalon Zerodur spacer corresponding to a shift of 13cm s-1 per day.

Original languageEnglish
Article number025003
Pages (from-to)1-10
Number of pages10
JournalJournal of Astronomical Telescopes, Instruments, and Systems
Issue number2
Publication statusPublished - 2017


  • echelle spectrograph
  • radial velocity
  • etalon
  • comb
  • frequency standard
  • optical fibers


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