The DESI slit design: science and calibration solutions

The Dark Energy Survey Instrument (DESI) is a 5000-fibre optical multi object spectrograph for the 4m Mayall telecope at the Kitt Peak National Observatory. Ten identical three channel spectrographs will be equipped with 500-element fibre slits. Here we focus on the architecture of the science slits and the interchangeable auxiliary slits required for calibration.