An Etymological Dictionary of Astronomy and Astrophysics

A major → redshift survey using a dedicated 2.5-m wide angle telescope with different modes in → imaging and → spectroscopy. The telescope, a modified → Ritchey-Chretien→ altitude-azimuth type is located at Apache Point Observatory, south east New Mexico, United States.

A large consortium of universities and institutions all over the world participate in the project.

The telescope started its observations in 2000,
taking spectra and images of about 35% of the night sky, with 3
million spectra and 500 million images coming together to form the
most comprehensive astrophysical catalog in the world. This

catalog contains millions of galaxies up to z = 1, bright → quasars up to z = 6, with images in five major filter bands (u, g, r, i and z).

SDSS was divided into multiple surveys/projects:

SDSS I (2000-2005); SDSS II (2005-2008), including the Sloan Supernova Survey; SDSS III (2008-2014), including the APO Galactic Evolution Experiment (APOGEE), Baryon Oscillation Spectroscopic Survey (BOSS); SDSS IV (2014-2020), including the Mapping Nearby Galaxies at APO (MaNGA).

See also: Named after the Alfred P. Sloan Foundation, which contributed significant funding; → digital; → sky; → survey.