Near infared spectra and telluric absorption: How to deal with it?

Solène Ulmer-Moll, P. Figueira, J. J. Neal, N.C.Santos

The absorption by the Earth’s atmosphere is a major limiting factor for near-infrared spectroscopy. Correcting for this 
absorption is essential to characterize exoplanet atmospheres and derive precise radial velocity measurements in the 
near-infrared domain. As computation of the atmospheric transmission is one of the many applications of the radiative 
transfer equation, the last few years have seen the development of several codes which produce a synthetic 
transmission spectra of the Earth’s atmosphere at the time of the observations. These codes (Molecfit from Smette et al. 
2015,  TelFit from Gullikson et al. 2014 and TAPAS from Bertaux et al. 2014) make obsolete the use of telluric standard 
stars to correct for the telluric  absorption. They are only made possible by the growing completeness of the molecular 
databases such as HITRAN, the use of radiative transfer code  like LBLRTM and the availability of atmospheric profiles. I 
will show with CRIRES data how the different codes perform the correction of the tellurics, which are the impact of the 
correction depending on the molecules and on the level of absorption on the telluric correction.