title: In-situ determination of astro-comb calibrator lines to better than 10 cm s(-1).
abstract: Improved wavelength calibrators for high-resolution astrophysical spectrographs will be essential for precision radial velocity (RV) detection of Earth-like exoplanets and direct observation of cosmological deceleration. The astro-comb is a combination of an octave-spanning femtosecond laser frequency comb and a Fabry-Pérot cavity used to achieve calibrator line spacings that can be resolved by an astrophysical spectrograph. Systematic spectral shifts associated with the cavity can be 0.1-1 MHz, corresponding to RV errors of 10-100 cm/s, due to the dispersive properties of the cavity mirrors over broad spectral widths. Although these systematic shifts are very stable, their correction is crucial to high accuracy astrophysical spectroscopy. Here, we demonstrate an in-situ technique to determine the systematic shifts of astro-comb lines due to finite Fabry-Pérot cavity dispersion. The technique is practical for implementation at a telescope-based spectrograph to enable wavelength calibration accuracy better than 10 cm/s.
authors.affiliation: Department of Physics, Harvard University, USA. chli@cfa.harvard.edu
authors.forename: Chih-Hao
authors.initials: CH
authors.lastname: Li
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Glenday
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Benedick
authors.forename: Guoqing
authors.initials: G
authors.lastname: Chang
authors.forename: Li-Jin
authors.initials: LJ
authors.lastname: Chen
authors.forename: Claire
authors.initials: C
authors.lastname: Cramer
authors.forename: Peter
authors.initials: P
authors.lastname: Fendel
authors.forename: Gabor
authors.initials: G
authors.lastname: Furesz
authors.forename: Franz X
authors.initials: FX
authors.lastname: Kärtner
authors.forename: Sylvain
authors.initials: S
authors.lastname: Korzennik
authors.forename: David F
authors.initials: DF
authors.lastname: Phillips
authors.forename: Dimitar
authors.initials: D
authors.lastname: Sasselov
authors.forename: Andrew
authors.initials: A
authors.lastname: Szentgyorgyi
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Walsworth