The Sloan Digital Sky Survey aims to produce comprehensive, three-dimensional maps of the Universe. Starting in 2000, its first eight years of operation saw it measure the positions and magnitudes of over 230 million objects (galaxies, quasars and stars), including a previously unobserved ring of stars beyond the edge of our galaxy.
Using a dedicated 2.5m instrument at the Apache Point Observatory in New Mexico, the project will continue until 2014.
Image: The 2.5m Sloan Digital Sky Survey reflecting telescope (credit: Fermilab Visual Media Services)
The Sloan Digital Sky Survey or SDSS is a major multi-filter imaging and spectroscopic redshift survey using a dedicated 2.5-m wide-angle optical telescope at Apache Point Observatory in New Mexico, United States. The project was named after the Alfred P. Sloan Foundation, which contributed significant funding.
Data collection began in 2000, and the final imaging data release covers over 35% of the sky, with photometric observations of around 500 million objects and spectra for more than 1 million objects. The main galaxy sample has a median redshift of z = 0.1; there are redshifts for luminous red galaxies as far as z = 0.7, and for quasars as far as z = 5; and the imaging survey has been involved in the detection of quasars beyond a redshift z = 6.
Data release 8 (DR8), released in January 2011, includes all photometric observations taken with the SDSS imaging camera, covering 14,555 square degrees on the sky (just over 35% of the full sky). Data release 9 (DR9), released to the public on 31 July 2012, includes the first results from the Baryon Oscillation Spectroscopic Survey (BOSS) spectrograph, including over 800,000 new spectra. Over 500,000 of the new spectra are of objects in the Universe 7 billion years ago (roughly half the age of the universe). Data release 10 (DR10), released to the public on 31 July 2013, includes all data from previous releases, plus the first results from the APO Galactic Evolution Experiment (APOGEE) spectrograph, including over 57,000 high-resolution [infrared] spectra of stars in the Milky Way. DR10 also includes over 670,000 new BOSS spectra, of galaxies and quasars in the distant universe.