Legacy Survey - DECaLS

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.

Current Status

The fifth data release (DR5) includes a portion of DECaLS, covering a disjoint footprint with 7400 deg² in g-band, 8000 deg² in r-band and 10200 deg² in z-band, of which 6800 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 May 2017. DR5 also includes DECam data from a range of non-DECaLS surveys, including observations that were conducted from September 2012 to March 2016. DR5 involved a re-processing of all previous DR3 data in addition to the new observations, and supersedes DR3.

Observing

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.