Legacy Survey - BASS

The Beijing-Arizona Sky Survey (BASS) will cover ~5000 deg² in the g, r bands to depths of g=24.4, r=23.9.

Current Status

The eighth data release (DR8) covers the full footprint of BASS (~5000 deg2) in g-band and r-band. DR8-north includes BASS images taken from 12th November 2015 through 7th March 2019.


The observations are taken with 90Prime on the Bok telescope in three passes at each sky location, and in each filter (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.

In the g-band, single exposures reach 5-sigma point source depth of 23.92 (pass 1), 23.89 (pass 2), and 23.89 (pass 3). In the r-band, single exposures reach depths of 23.30 (pass 1), 23.30 (pass 2), and 23.18 (pass 3).

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.