title: Optical and radiometric models of the NOMAD instrument part I: the UVIS channel.
abstract: 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 (>1000) can easily be reached for wavelengths higher than 300nm both in solar occultation and nadir modes when considering binning. Below 300nm SNR are lower primarily because of the lower signal and the impact of atmospheric absorption.
authors.forename: Ann C
authors.initials: AC
authors.lastname: Vandaele
authors.forename: Yannick
authors.initials: Y
authors.lastname: Willame
authors.forename: Cédric
authors.initials: C
authors.lastname: Depiesse
authors.forename: Ian R
authors.initials: IR
authors.lastname: Thomas
authors.forename: Séverine
authors.initials: S
authors.lastname: Robert
authors.forename: David
authors.initials: D
authors.lastname: Bolsée
authors.forename: Manish R
authors.initials: MR
authors.lastname: Patel
authors.forename: Jon P
authors.initials: JP
authors.lastname: Mason
authors.forename: Mark
authors.initials: M
authors.lastname: Leese
authors.forename: Stefan
authors.initials: S
authors.lastname: Lesschaeve
authors.forename: Philippe
authors.initials: P
authors.lastname: Antoine
authors.forename: Frank
authors.initials: F
authors.lastname: Daerden
authors.forename: Sofie
authors.initials: S
authors.lastname: Delanoye
authors.forename: Rachel
authors.initials: R
authors.lastname: Drummond
authors.forename: Eddy
authors.initials: E
authors.lastname: Neefs
authors.forename: Bojan
authors.initials: B
authors.lastname: Ristic
authors.forename: José-Juan
authors.initials: JJ
authors.lastname: Lopez-Moreno
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Bellucci
authors.forename: Nomad
authors.initials: N
authors.lastname: Team