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 eighth data release (DR8) includes the full footprint of DECaLS in all three optical filters (DR8-south).

Images from DECaLS g, r, z-band observations (NOAO survey program 2014B-0404) are included from 9th August 2014 through 7th March 2019. DR8 also includes DECam data from a range of non-DECaLS surveys, including observations that were conducted from 1st September 2013 to 7th March 2019. A large portion of these non-DECaLS observations were taken by the Dark Energy Survey team. DR8 supersedes DR7 and previous DECaLS releases.

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.

Joining DR8-north & DR8-south

Unique area is resolved by including the BASS and MzLS images (from DR8-north) if they are both at Declination > 32.375° and north of the Galactic Plane. Otherwise, the DECam images (from DR8-south) are used.