Please contact Beth Demkowski, demkowsk@umich.edu for Zoom link.

The Dark Energy Spectroscopic Instrument (DESI) is a multi-object fiber spectrograph on the Mayall 4-meter telescope at Kitt Peak National Observatory. DESI consists of a new wide-field optical corrector and a 3-degree focal plane with 5000 robotic fiber positioners feeding into ten broadband spectrographs. The large number of spectra obtained in a single exposure will enable a five-year spectroscopic survey of over a third of the sky. DESI will obtain redshifts for more than 35 million objects including luminous red galaxies, emission line galaxies and quasar Ly-a forest spectra, creating the most detailed 3-dimensional map of the universe to date.

The DESI focal plane is composed of ten identical wedge-shaped petals which were integrated and tested at Lawrence Berkeley Laboratory and installed at Kitt Peak during the Summer of 2019. DESI completed commissioning in March 2020 just days before mountain operations had to be put on hold due to the COVID-19 pandemic. During Commissioning, 12 million on-sky spectra were taken and two dark time mini surveys were completed. Following a brief overview of DESI I will highlight some of the milestones during construction and installation of the DESI instrument. I will close by touching on some of the results from the commissioning phase.