The 13th Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies at Apache Point Observatory

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) beganobservations in 2014 July. It pursues three core programs: the ApachePoint Observatory Galactic Evolution Experiment 2 (APOGEE-2), MappingNearby Galaxies at APO (MaNGA), and the Extended Baryon OscillationSpectroscopic Survey (eBOSS). As well as its core program, eBOSScontains two major subprograms: the Time Domain Spectroscopic Survey(TDSS) and the SPectroscopic IDentification of ERosita Sources(SPIDERS). This paper describes the first data release from SDSS-IV,Data Release 13 (DR13). DR13 makes publicly available the first 1390spatially resolved integral field unit observations of nearby galaxiesfrom MaNGA. It includes new observations from eBOSS, completing theSloan Extended QUasar, Emission-line galaxy, Luminous red galaxy Survey(SEQUELS), which also targeted variability-selected objects andX-ray-selected objects. DR13 includes new reductions of the SDSS-IIIBOSS data, improving the spectrophotometric calibration and redshiftclassification, and new reductions of the SDSS-III APOGEE-1 data,improving stellar parameters for dwarf stars and cooler stars. DR13provides more robust and precise photometric calibrations. Value-addedtarget catalogs relevant for eBOSS, TDSS, and SPIDERS and an updatedred-clump catalog for APOGEE are also available. This paper describesthe location and format of the data and provides references to importanttechnical papers. The SDSS web site, http://www.sdss.org, provides links tothe data, tutorials, examples of data access, and extensivedocumentation of the reduction and analysis procedures. DR13 is thefirst of a scheduled set that will contain new data and analyses fromthe planned ∼6 yr operations of SDSS-IV.