The Dark Energy Camera Legacy Survey (DECaLS) will cover ~9500 deg² in the g, r, z bands to depths of g=24.7, r=23.9, z=23.0. Infrared WISE data are also extracted at the location of the DECaLS sources.
The third data release (DR3) includes a portion of DECaLS, covering a disjoint footprint with 4300 deg² in g-band, 4600 deg² in r-band and 8100 deg² in z-band, of which 4200 deg² has been observed in all three optical filters.
Images from DECaLS g, r, z-band observations (NOAO survey program 2014B-0404) are included from August 2014 through March 2016. DR3 also includes DECam data from a range of non-DECaLS surveys, including observations that were conducted from September 2012 to March 2016.
The observations are taken with DECam on the 4-meter Blanco telescope in three passes at each sky location, and in each filter (g, r, z). "Pass 1" is observed in photometric, good-seeing conditions. "Pass 2" and "Pass 3" are observed in progressively worse conditions. This strategy was adopted to ensure a photometric solution across the full survey area. The observing time is adjusted as a function of sky brightness and transparency.