DESI opens its 5000 eyes

DESI’s 5000 spectroscopic “eyes” can cover an area of sky approximately 38 times larger than the full moon, as seen in this overlay of DESI’s focal plane on the night sky (top). Each of the robotically controlled eyes can fix a fiber-optic cable on a single galaxy or star to gather its light. The green dot marks the location of a single fiber positioner. In this first light spectrum captured by DESI, the light gathered from a small region in the Triangulum Galaxy, Messier 33, by a single fiber-optic cable is dispersed into a spectrum (bottom) that reveals emission lines. The lines both encode the elements present in the galaxy and aid in gauging the galaxy’s distance.