The recently commissioned Dark Energy Spectroscopic Instrument (DESI) will measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 35 million galaxies and quasars over 14,000 sq deg will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope delivers light to 5,000 fiber optic positioners which in turn feed ten broad-band spectro-graphs. The DESI focal plane subsystem contains the fiber optic positioners and guide and focus cameras, which enable the alignment of fibers with astronomical targets. This paper describes the performance of the installed instrument.
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