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The Sloan Digital Sky Survey

The Sloan Digital Sky Survey is an ambitious, multi–institutional project to create a huge digital imaging and spectroscopic data bank of 25% of the celestial sphere, approximately 10,000 degrees square centred on the north galactic polar cap. The photometric atlas will be in five specially chosen colours, covering the π sr of the Survey area to a limiting magnitude of r′ ∼ 23.1, on 0″.4 pixels, resulting in a 1Tpixel map. This database will be automatically analysed to catalogue the photometric and astrometric properties of 108 stellar images, 108 galaxies, and 106 colour–selected QSO candidates; the galaxy data will, in addition, include detailed morphological data. The photometric data are used to autonomously and homogeneously select objects for the spectroscopic survey, which will include spectra of 106 galaxies, 105 QSOs, and 105 unusual stars. Although the project was originally motivated by the desire to study ‘large scale structure’, we anticipate that these data will impact on virtually every field of astronomy, from Earth–crossing asteroids to QSOs at z > 6. In particular, the ca. 12 TByte multi–colour precision–calibrated imaging archive should be a world resource for many decades of the next century.