In order to identify the targets for DESI’s operations, we must complete imaging surveys across the 14,000 square degrees of the DESI survey area.

These imaging surveys, the Legacy Surveys, will produce a catalog of the sky from a set of optical and infrared imaging data of the extragalactic sky visible from the Northern Hemisphere in three optical bands (g,r,z) and four infrared bands. The sky coverage is approximately bounded by -18° < δ < +84° in celestial coordinates and |b| > 15° in Galactic coordinates. To achieve this goal, the Legacy Surveys are conducting three imaging projects on different telescopes, described in more depth at the following links:

  • DECaLS: The DECam Legacy Survey at the Blanco telescope at Cerro Tololo
  • BASS: The Beijing-Arizona Sky Survey at the BOK telescope at Kitt Peak
  • MzLS: The Mayall z-band Legacy Survey at the Mayall telescope at Kitt Peak

The data from the Legacy Surveys are available to the public here.