Date Published:

July 1, 2017

Abstract:

We describe the Sloan Digital Sky Survey IV (SDSS-IV), a projectencompassing three major spectroscopic programs. The Apache PointObservatory Galactic Evolution Experiment 2 (APOGEE-2) is observinghundreds of thousands of Milky Way stars at high resolution and highsignal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxiesat Apache Point Observatory (MaNGA) survey is obtaining spatiallyresolved spectroscopy for thousands of nearby galaxies (median z˜0.03). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) ismapping the galaxy, quasar, and neutral gas distributions between z˜0.6 and 3.5 to constrain cosmology using baryon acoustic oscillations,redshift space distortions, and the shape of the power spectrum. WithineBOSS, we are conducting two major subprograms: the SPectroscopicIDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNsand galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey(TDSS), obtaining spectra of variable sources. All programs use the 2.5m Sloan Foundation Telescope at the Apache Point Observatory;observations there began in Summer 2014. APOGEE-2 also operates a secondnear-infrared spectrograph at the 2.5 m du Pont Telescope at LasCampanas Observatory, with observations beginning in early 2017.Observations at both facilities are scheduled to continue through 2020.In keeping with previous SDSS policy, SDSS-IV provides regularlyscheduled public data releases; the first one, Data Release 13, was madeavailable in 2016 July.

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