Beijing-Arizona Sky Survey (BASS)

The Beijing-Arizona Sky Survey (BASS) is an ambitious wide-field multicolor survey of 5000 deg2 of the Northern Galactic Cap using the 90prime imager on the 2.3m Bok Telescope at Kitt Peak, as a three to four-year collaboration between the Chinese team led by NAOC and the US team led by Steward Observatory, University of Arizona. The survey will use 240 nights, covering SDSS g and r bands, reaching limiting AB magnitude of 24.0 and 23.6 (5σ), respectively. The survey will follow the successful SCUSS mode with strong participations and support from both China and US teams and produce high level science products for the general astronomical community. The survey data will allow effective target selection for the DESI dark energy spectroscopic survey project in the survey area. There are three image surveys that consititues the DESI imaging legacy surveys, which are mainly used for DESI spectroscopic targeting: the BASS, Mayall z-band Legacy Survey (MzLS), and the DECam Legacy Survey (DECaLS). The BASS and MzLS cover the same area of about 5500 deg2 in the north Galactic cap, while the DECaLS cover an area of about 9000 deg2 along the equator in both south and north. The DESI team produces the catalogs for spectroscopic targetting. The latest data release (DR4) include the BASS and MzLS data taken before 2016 July. The BASS team has published its early data release (EDR)in Dec. 2015, First Data Release in Jan. 2017, and Second Data Release in Dec. 2017.