Overview of the DESI Legacy Imaging Surveys
Abstract
The DESI imaging Legacy Surveys (www.legacysurvey.org) are a combination of three public projects (the Dark Energy Camera Legacy Survey, the Beijing-Arizona Sky Survey, and the Mayall z-band Legacy Survey) that are jointly imaging 14,000 square degrees of the extragalactic sky visible from the northern hemisphere in three optical bands (g, r, and z) using telescopes at the Kitt Peak National Observatory and the Cerro Tololo Inter-American Observatory. The optical imaging is conducted using an innovative dynamic observing strategy that results in a survey of nearly uniform depth. In addition to calibrated images, the project is delivering an inference-based catalog (using the "Tractor" code) which includes photometry from the grz optical bands and from four mid-infrared bands (at 3.4, 4.6, 12 and 22 microns) observed by the Wide-field Infrared Survey Explorer (WISE) satellite during its full operational lifetime. The Legacy Surveys will enable the selection of 40 million spectroscopic targets for the Dark Energy Spectroscopic Instrument (DESI), a next-generation redshift survey slated to begin its five year mission in early 2020. These DESI targets include luminous red galaxies to redshift 1, emission line galaxies to redshift 1.6, quasars to redshift 3.5, a dense sample of bright galaxies in the local Universe, and 10 million Milky Way stars. More broadly, the Legacy Surveys provide a much deeper multi-purpose successor to the Sloan Digital Sky Survey imaging catalog over a similar footprint, with science applications ranging from faint dwarf galaxies to the most distant known quasars. The most recent northern and equatorial public data releases (DR6 and DR7, respectively), combine to include 1.2 billion unique sources and achieve depths of 24.7, 23.9 and 23.0 in g, r, and z.
- Publication:
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American Astronomical Society Meeting Abstracts #233
- Pub Date:
- January 2019
- Bibcode:
- 2019AAS...23338003S