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

TL;DR

This paper introduces a method to synthesize and correct telluric features in high-resolution astronomical spectra, enabling accurate calibration and removal of atmospheric effects without standard star observations.

Contribution

The paper presents a novel technique for synthesizing telluric features that improves calibration accuracy and reduces the need for telluric standard star observations in high-resolution spectra.

Findings

Synthetic spectra reproduce telluric features to about 2% accuracy.

The method enables in-situ wavelength calibration.

It can replace traditional telluric standard star observations.

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.