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The Sloan Digital Sky Survey (SDSS) plans to produce an archive of digital images and spectra over about 10,000 square degrees of the sky. The survey is designed to provide a reference view of the Universe out to z~0.1, by producing a database of precise coordinates, image profiles, and intensities in five bands of galaxies, QSO's, and selected stars. The database will be particularly useful for studies of large scale structure at low redshift, using galaxies, and at high redshift, using QSO's and QSO absorption lines.
The hardware for the survey consists of a 2.5 meter telescope of novel design, with a three degree field of view; a CCD camera, containing 30 CCD's of 4 million pixels each, arranged and filtered to give coverage of 0.3 square degrees of sky per minute in each of five color bands; two, fiber-fed, double spectrographs with a resolving power of 2000, arranged to yield 640 spectra simultaneously; and a 24 inch auxiliary telescope used to derive extinction coefficients and establish secondary flux standards in conjunction with the main survey. The magnitude limit is about 23 for imaging (5 standard deviation significance) and about 19 for spectroscopy.
Drift scanning with the photometric camera will be done on the best nights. The processed data will be reduced in near real time and used to select objects for the spectroscopic survey, to be done on the remaining clear, dark nights. In five years, we expect to obtain spectra of 1 million objects and images of over 100 million objects. The survey will cover pi contiguous radians above +30 degrees Northern Galactic latitude and about 0.1 steradians, parts to a greater depth, in the Southern hemisphere.
Partners in the project are the University of Chicago, Fermi National Accelerator Laboratory, the Institute for Advanced Study, the Japanese Participation Group, the Johns Hopkins University, Princeton University, the U.S. Naval Observatory, and the University of Washington.
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