Abstract

This paper describes the Seventh Data Release of the Sloan Digital Sky Survey (SDSS), marking the completion of the original goals of the SDSS and the end of the phase known as SDSS-II. It includes 11,663deg2 of imaging data, with most of the 2000deg2 increment over the previous data release lying in regions of low Galactic latitude. The catalog contains five-band photometry for 357million distinct objects. The survey also includes repeat photometry on a 120° long, 25 wide stripe along the celestial equator in the Southern Galactic Cap, with some regions covered by as many as 90individual imaging runs. We include a co-addition of the best of these data, going roughly 2mag fainter than the main survey over 250deg2. The survey has completed spectroscopy over 9380deg2; the spectroscopy is now complete over a large contiguous area of the Northern Galactic Cap, closing the gap that was present in previous data releases. There are over 1.6million spectra in total, including 930,000galaxies, 120,000quasars, and 460,000stars. The data release includes improved stellar photometry at low Galactic latitude. The astrometry has all been recalibrated with the second version of the USNO CCD Astrograph Catalog, reducing the rms statistical errors at the bright end to 45milliarcseconds per coordinate. We further quantify a systematic error in bright galaxy photometry due to poor sky determination; this problem is less severe than previously reported for the majority of galaxies. Finally, we describe a series of improvements to the spectroscopic reductions, including better flat fielding and improved wavelength calibration at the blue end, better processing of objects with extremely strong narrow emission lines, and an improved determination of stellar metallicities. © 2009. The American Astronomical Society. All rights reserved.