SDSSIII

SDSS-III, the third phase of the Sloan Digital Sky Survey, was an astronomical survey project that ran from 2008 to 2014 using the 2.5-meter Sloan telescope at Apache Point Observatory in New Mexico. Building on SDSS-I and SDSS-II, SDSS-III conducted a series of large spectroscopic and ancillary surveys designed to map the distribution of galaxies and quasars, trace the structure of the Milky Way, and search for exoplanets.

The four main projects of SDSS-III were BOSS, the Baryon Oscillation Spectroscopic Survey, which measured spectra of tens of thousands of galaxies and quasars to map the cosmos and measure baryon acoustic oscillations; SEGUE-2, the Sloan Extension for Galactic Understanding and Exploration, which obtained spectra of stars to study the Milky Way's components; APOGEE, the Apache Point Observatory Galactic Evolution Experiment, a high-resolution infrared spectroscopic survey of hundreds of thousands of Milky Way stars to determine chemical abundances and motions; and MARVELS, the Multi-object APO Radial Velocity Exoplanet Large-area Survey, a radial-velocity survey aimed at detecting exoplanets around nearby stars.

Data were collected with the Sloan telescope and dedicated spectrographs, including an infrared spectrograph for APOGEE and optical spectrographs for BOSS and SEGUE. The project produced several public data releases, culminating in the SDSS Data Release 12 in 2014.

SDSS-III significantly advanced cosmology, Galactic astronomy, and exoplanet science, providing datasets widely used in research and forming a foundation for the subsequent SDSS-IV program.