Broadband near-infrared astronomical spectrometer calibration and on-sky validation with an electro-optic laser frequency comb
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Author
Obrzud, Ewelina
Rainer, Monica
Harutyunyan, Avet
Chazelas, Bruno
Cecconi, Massimo
Ghedina, Adriano
Molinari, Emilio
Kundermann, Stefan
Lecomte, Steve
Pepe, Francesco
DOI
10.1364/OE.26.034830
Abstract
The quest for extrasolar planets and their characterization 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-fiber, 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 cms 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.
Publication Reference
Optics Express, vol. 26 (26), pp. 34830-34841
Year
2018-12-24