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

TL;DR

DR13 marks the inaugural SDSS-IV data release, consolidating new MaNGA IFU data, SEQUELS-enabled eBOSS/TDSS/SPIDERS data, and reprocessed SDSS-III/IV data with improved imaging calibration and value-added catalogs. The release provides extensive, publicly accessible data products (RSS, datacubes, DRP reductions, and APOGEE-1 updates) that enable spatially resolved studies of galaxies, cosmological measurements across redshift, and a richer Galactic chemical map. Key contributions include the largest public IFU galaxy sample to date, refined redshift classifications for LRGs via Redmonster, and expanded APOGEE abundances with cool-star grids, alongside robust data-access tools via SAS, CAS, and SciServer. These data will support a broad range of galaxy evolution, AGN, and Milky Way studies, with future DRs expanding coverage and analysis capabilities.

Abstract

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in July 2014. It pursues three core programs: APOGEE-2, MaNGA, and eBOSS. In addition, eBOSS contains two major subprograms: TDSS and SPIDERS. This paper describes the first data release from SDSS-IV, Data Release 13 (DR13), which contains new data, reanalysis of existing data sets and, like all SDSS data releases, is inclusive of previously released data. DR13 makes publicly available 1390 spatially resolved integral field unit observations of nearby galaxies from MaNGA, the first data released from this survey. It includes new observations from eBOSS, completing SEQUELS. In addition to targeting galaxies and quasars, SEQUELS also targeted variability-selected objects from TDSS and X-ray selected objects from SPIDERS. DR13 includes new reductions of the SDSS-III BOSS data, improving the spectrophotometric calibration and redshift classification. DR13 releases new reductions of the APOGEE-1 data from SDSS-III, with abundances of elements not previously included and improved stellar parameters for dwarf stars and cooler stars. For the SDSS imaging data, DR13 provides new, more robust and precise photometric calibrations. Several value-added catalogs are being released in tandem with DR13, in particular target catalogs relevant for eBOSS, TDSS, and SPIDERS, and an updated red-clump catalog for APOGEE. This paper describes the location and format of the data now publicly available, as well as providing references to the important technical papers that describe the targeting, observing, and data reduction. The SDSS website, http://www.sdss.org, provides links to the data, tutorials and examples of data access, and extensive documentation of the reduction and analysis procedures. DR13 is the first of a scheduled set that will contain new data and analyses from the planned ~6-year operations of SDSS-IV.

Figures (11)

• Figure 1: In grey are shown the locations in equatorial coordinates of all possible plates with MaNGA galaxies, each containing 17 galaxy targets. Because the MaNGA targets are selected to have SDSS photometry, this footprint corresponds to the Data Release 7 imaging data 2009ApJS..182..543A. Approximately 30% of these will be observed in the full planned MaNGA survey. The blue shows the plates observed in the first year of MaNGA for which data cubes are released in this paper.
• Figure 2: Coverage of DR13 data from BOSS and SEQUELS in equatorial coordinates. The blue areas show the locations in equatorial coordinates of the five new BOSS plates (SGC) and the 126 SEQUELS plates (NGC) released in DR13. The green represents the area covered by BOSS in DR12. The SEQUELS plates released in DR12 lie in the same region as the new ones in DR13, providing complete coverage over roughly 400 square degrees.
• Figure 3: Coverage of APOGEE-2 DR13 data in Galactic coordinates; the raw data and its coverage is the same as in DR12, but it has been reprocessed through the latest reduction pipeline and ASPCAP versions. The color coding denotes the number of visits to each field, as indicated in the legend.
• Figure 4: Principal selection cuts for the main MaNGA samples, where $h = H_0 / 100 \ {\rm km \ s}^{-1}$. The colored bands show the selection cuts for the Primary (orange) and Secondary (green) samples illustrating the M$_i$ dependence of the redshift limits. More luminous, and hence typically larger galaxies are selected at higher redshift than less luminous galaxies, ensuring that the angular size (1.5 $R_e$ or 2.5 $R_e$) distribution is roughly independent of luminosity. The volume sampled also increases as the luminosity increases in such a way as to ensure a constant number density of galaxies at all luminosities. The points show the positions in this plane for the MaNGA galaxies in DR13, for the Primary (red triangles), Secondary (green squares) and Color-Enhanced samples (blue stars), although the Color-Enhanced selection also depends on NUV-$i$color (see text for details). The numbers in the legend give the total number of observations of galaxies in each class, including repeat observations. The right hand y-axis gives an indication of the physical size of the mean spatial resolution element of the MaNGA data.
• Figure 5: The location of MaNGA galaxies (black triangles) in this data release area in the plane of stellar mass (M$_*$, $x$-axis) versus dark matter halo mass (M$_h$, $y$-axis). The two panels show red and blue galaxies separately,which are divided by a single color cut at $g-r=0.7$. Stellar masses are taken from the NASA-Sloan Atlas, and halo masses from SDSS/DR7, using the method of 2007ApJ...671..153Y.  Plotted as a colormap in the background are the number of MaNGA galaxies predicted for a 6-year full survey based  on mock catalogs informed by the semi-analytic model of 2011MNRAS.413..101G  and constructed as in 2006MNRAS.368...21L, which are the same as Figure 3 of Bundy_2015. Normalized histograms show 1D marginalized M$_*$ distributions (top axes) and M$_h$ distributions (right axes), with  dashed lines for the full primary sample and solid lines for the red (left) and blue (right) populations.