Modelling Earth's atmosphere for astronomy

Full text: Astronomical observations are strongly affected by physical processes within Earth's atmosphere. One the one hand, celestial photons are absorbed / scattered by molecules, on the other hand telluric emission causes significant background radiation, both reducing the astronomical signal. Amongst the contributing processes are scattered Moon light, Zodiacal light, airglow emission arising in the upper atmosphere (e.g. OH emission), and thermal emission in the troposphere. We have developed an accurate model incorporating these effects for Cerro Paranal, the observation site of ESO's Very Large Telescope. In the process, we have combined radiative transfer codes, line databases and a semi-empirical airglow model. Here we present the resulting model, which is used for planning astronomical observations, deriving atmospheric parameters (e.g. the amount of water vapour), and correcting telluric features in spectroscopic data. (author)