ProtoDESI is a subset of DESI subsystems. It was built to operate with a simplified prime focus instrument, a Fiber View Camera (FVC) for positioning feedback, Telescope Control System (TCS), and Instrument Control System (ICS). Rather than measuring the output of a 50-meter fiber cable with DESI’a spectrographs, ProtoDESI confirmed fiber pointing and stability with a fiber photometry camera (FPC) that imaged the ends of the short 3-meter fibers mounted on the prime focus instrument. The success of ProtoDESI relied heavily on the interaction of its hardware and software, and on the careful translation between focal plane coordinates and target locations. ProtoDESI was mounted to the Mayall telescope from Aug. 15 to Sept. 30, 2016.

A photo of DESI researchers taken after the first successful alignment of ProtoDESI fibers with targets.
ProtoDESI installed in the prime focus of the Mayall Telescope.