Optical and radiometric models of the NOMAD instrument part I: The UVIS channel
The NOMAD instrument has been designed to best fulfil the science objectives of the ExoMars Trace Gas Orbiter mission that will be launched in 2016. The instrument is a combination of three channels that cover the UV, visible and IR spectral ranges and can perform solar occultation, nadir and limb observations. In this series of two papers, we present the optical models representing the three channels of the instrument and use them to determine signal to noise levels for different observation modes and Martian conditions. In this first part, we focus on the UVIS channel, which will sound the Martian atmosphere using nadir and solar occultation viewing modes, covering the 200-650nm spectral range. High SNR levels (Interuniversity Attraction Poles> programme financed by the Belgian government (Planet TOPERS, contract PAI no P7/15). UK funding is acknowledged under the UK Space Agency grant ST/I003061/1. ; Peer Reviewed