APOGEE DR15 Synopsis

Data Release 15 provides reduced, visit-combined spectra as well as pipeline-derived stellar atmospheric parameters and individual elemental abundances for more than 263,000 stars, sampling all major components of the Milky Way.

No new data or reductions from the Apache Point Observatory Galactic Evolution Experiment (APOGEE-1/APOGEE-2) are included in Data Release 15 (DR15) compared to DR14. The documentation contained on these pages, however, have been updated appropriately for our current understanding of the data and reductions. DR14 contained data from SDSS-III (Sep 2011-Jul 2014; APOGEE-1) as well as two years of data from SDSS-IV (Jul 2014-Jul 2016; APOGEE-2). For convenience, the general term APOGEE is employed throughout the documentation and refers to both APOGEE-1 and APOGEE-2. The APOGEE survey probes numerous locations on the sky; DR15 encompasses data for 731 fields.

DR15 APOGEE Targets

DR15 Coverage

The figure below displays the DR15 APOGEE spectroscopic coverage in Galactic coordinates. The color coding indicates the number of APOGEE-1 and APOGEE-2 targets observed per field.

Distribution of fields contained in DR15, color-coded by the number of APOGEE-1 + APOGEE-2 targets. <em>Image credit: G. Zasowski</em>
Distribution of fields contained in DR15, color-coded by the number of APOGEE-1 + APOGEE-2 targets. Image credit: G. Zasowski

DR15 contains data for approximately 263,000 APOGEE targets, of which roughly 231,000 are considered to be main survey targets. A general breakdown of targets in DR15-associated fields follows below:

13,000 targets toward the Bulge
129,600 targets toward the Halo and Halo Streams plus MaNGA co-targeted fields
76,000 targets toward the Disk
3,200 targets toward Satellite Galaxies
19,500 targets toward Star Clusters
17,200 Asteroseismic targets

60 Eclipsing Binary Program objects
1,400 M Dwarf Program objects
400 Kepler Objects of Interest (KOI) Program objects
260 Substellar Companion Program objects
1,900 Young Cluster Program objects

13,300 Ancillary Program objects

With the NMSU 1m-APOGEE telescope-spectrograph combination (Holtzman et al. 2010), spectra of roughly 1000 bright targets were acquired, including various types of standard stars. Additionally, 27,000 telluric standards have been observed in the assorted APOGEE fields.

DR15 Scope and Updates

APOGEE-1 commenced data acquisition in September 2011 and concluded almost 3 years later in July 2014. The first release of APOGEE-1 data occurred in DR10 followed by two subsequent releases DR12 (July 2015) and DR13 (July 2016).

APOGEE-2 started operations immediately after APOGEE-1 in July 2014 and will be conducted through mid-2020. The first release of APOGEE-2 data transpired in DR14, which encompassed the whole of SDSS-III as well as a portion of SDSS-IV. DR15 contains no new data or reductions, but the documentation has been updated to reflect a growing understanding of the data and reductions.

APOGEE-2 has expanded upon APOGEE-1 with the addition of new targeting classes (e.g., satellite galaxies) as well as the MaNGA-APOGEE Co-Observing Program. DR15 features these data. See targeting page for details of targeting expansions.

For all targets, DR15 provides heliocentric radial velocities, stellar atmospheric parameters, and calibrated abundance measurements for up to 20 individual species: C, C I, N, O, Na, Mg, Al, Si, P, S, K, Ca, Ti, Ti II, V, Cr, Mn, Fe, Co, and Ni.

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What to expect in DR16

While there are no new data or reductions for APOGEE included in DR15, the next data release (DR16) will have a number of new additions:

  • First release of APOGEE-2S data.
  • Special campaigns in the TESS Northern Continuous Viewing Zone and K2.
  • New ancillary and external programs.
  • Updates to ASPCAP including an updated line list, new synthetic spectral grid, improved handling of the LSF, and mini-grid analysis.
  • New VACs including catalogs using Gaia DR2.
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