Broadband near-infrared astronomical spectrometer calibration and on-sky validation with an electro-optic laser frequency comb
Abstract
The quest for extrasolar planets and their characterisation as well as studies of fundamental physics on cosmological scales rely on capabilities of high-resolution astronomical spectroscopy. A central requirement is a precise wavelength calibration of astronomical spectrographs allowing for extraction of subtle wavelength shifts from the spectra of stars and quasars. Here, we present an all-fibre, 400 nm wide near-infrared frequency comb based on electro-optic modulation with 14.5 GHz comb line spacing. Tests on the high-resolution, near-infrared spectrometer GIANO-B show a photon-noise limited calibration precision of <10 cm/s as required for Earth-like planet detection. Moreover, the presented comb provides detailed insight into particularities of the spectrograph such as detector inhomogeneities and differential spectrograph drifts. The system is validated in on-sky observations of a radial velocity standard star (HD221354) and telluric atmospheric absorption features. The advantages of the system include simplicity, robustness and turn-key operation, features that are valuable at the observation sites.
Keywords
Cite
@article{arxiv.1808.00860,
title = {Broadband near-infrared astronomical spectrometer calibration and on-sky validation with an electro-optic laser frequency comb},
author = {Ewelina Obrzud and Monica Rainer and Avet Harutyunyan and Bruno Chazelas and Massimo Cecconi and Adriano Ghedina and Emilio Molinari and Stefan Kundermann and Steve Lecomte and Francesco Pepe and François Wildi and François Bouchy and Tobias Herr},
journal= {arXiv preprint arXiv:1808.00860},
year = {2019}
}