The DESI instrument control system

The Dark Energy Spectroscopic Instrument (DESI) , a new instrument currently under construction for the Mayall 4m telescope at Kitt Peak National Observatory, will consist of a wide-field optical corrector with a 3.2 degree diameter field of view, a focal plane with 5,000 robotically controlled fiber positioners and 10 fiber fed broadband spectrographs. This article describes the design of the DESI instrument control system (ICS). The ICS coordinates fiber positioner operations, interfaces to the Mayall telescope control system, monitors operating conditions, reads out the 30 spectrograph CCDs and provides observer support and data quality monitoring.