Zooming in on 500 DESI spectra

DESI’s robotic fiber positioners, which gather the light from individual galaxies and stars, are arranged in 10 wedge-shaped modules called “petals.” Left: a portion of the night sky, studied by one petal, that includes the galaxy Messier 33. Blue circles demarcate the region of sky that can be studied by each of the 500 fibers in the petal; each fiber can point to any position within its circle. Right: The hydrogen line emission detected by DESI from Messier 33, shown as a color map, with brighter colors indicating brighter emission.