Synthesising, using, and correcting for telluric features in high-resolution astronomical spectra

A near-infrared case study using CRIRES^⋆

¹ Physics DepartmentUniversity of California, Davis, CA 95616, USA
e-mail: seifahrt@physics.ucdavis.edu
² Universität Göttingen, Institut für Astrophysik, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
³ European Southern Observatory (ESO), Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
⁴ Ludwig-Maximilians-Universität München, Meteorologisches Institut, Theresienstrasse 37, 80333 Munich, Germany
⁵ Deutscher Wetterdienst, Frankfurter Str. 135, 63067 Offenbach, Germany

Received: 1 December 2009
Accepted: 18 August 2010

Abstract

We present a technique to synthesise telluric absorption and emission features both for in-situ wavelength calibration and for their removal from astronomical spectra. While the presented technique is applicable for a wide variety of optical and infrared spectra, we concentrate in this paper on selected high-resolution near-infrared spectra obtained with the CRIRES spectrograph to demonstrate its performance and limitation. We find that synthetic spectra reproduce telluric absorption features to about 2%, even close to saturated line cores. Thus, synthetic telluric spectra could be used to replace the observation of telluric standard stars, saving valuable observing time. This technique also provides a precise in-situ wavelength calibration, especially useful for high-resolution near-infrared spectra in the absence of other calibration sources.