NOMAD spectrometer on the ExoMars trace gas orbiter mission: part 2-design, manufacturing, and testing of the ultraviolet and visible channel

NOMAD is a spectrometersuite on board the ESA/Roscosmos ExoMars Trace GasOrbiter, which launched in March 2016. NOMAD consists of two infrared channels and one ultravioletand visible channel, allowing the instrument to perform observations quasi-constantly, by taking nadirmeasurements at the day- and night-side, and during solar occultations. Here, in part 2 of a linked study, we describe the design, manufacturing, and testing of the ultravioletand visible spectrometerchannel called UVIS. We focus upon the optical design and working principle where two telescopes are coupled to a single grating spectrometerusing a selector mechanism.