APOGEE DR14 Synopsis
DR14 APOGEE Targets
DR14 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 DR14-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, spectra of roughly 1000 bright targets were acquired, including various types of standard stars. Additionally, 27,000 tellurics have been observed in the assorted APOGEE fields.
Data Release 14 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.
Data Release 14 (DR14) is the fourth spectroscopic release from the Apache Point Observatory Galactic Evolution Experiment (APOGEE-1/APOGEE-2). DR14 contains all 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; DR14 encompasses data for 731 fields.
DR14 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 transpires in DR14. Altogether, DR14 includes the full set of APOGEE observations through July 2016 (encompassing the whole of SDSS-III as well as a portion of SDSS-IV).
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. DR14 features these data. See targeting page for details of targeting expansions.
Compared to prior releases, DR14 spectra have been reprocessed with modified data reduction and abundance pipelines. Specific changes implemented for DR14 are as follows:
- The blue detector chip of the APOGEE-North spectrograph was replaced during the 2014 Summer Shutdown (this new chip has lower levels of persistence).
- As in DR13, modifications have been made to reduce the effects of persistence for data taken with the original blue chip, by downweighting pixels affected by persistence. Some fixes were also made to the routines that attempt to correct for persistence, and a bug where PERSIST_LOW pixels were given very large inflated errors instead of SKY pixels was fixed.
- Two modifications to the RV determination and associated star combination have been put into place. First, the search for template spectra for RVs was limited in Teff depending on the dereddened J-K color of the star. Second, the relative RVs have been determined both relative to the combined spectrum (iteratively) as well as to the best-matching model. Previously, the former were always adopted, but in DR14, the latter is adopted if it yields lower scatter.
- A new normalization scheme was implemented in the ASPCAP determinations. Rather than using an iteratively asymmetrically-clipped fit, the continuum was determined by a polynomial fit to the spectra, after masking of sky lines. The asymmetric clipping previously used leads to systematic differences in continuum normalization as a function of S/N
- A 7D grid, which now includes microturbulence, was employed in the ASPCAP parameter derivation for giants. In previous releases, ASPCAP relied upon 6D grid in that a microturbulent velocity relation as a function of surface gravity was used. The result of this modification appears to be slightly lower abundance scatter as well as slightly smaller trends of raw abundances with temperature.
For all targets, DR14 provides heliocentric radial velocities, stellar atmospheric parameters, and calibrated abundance measurements of 20 individual species: C, CI, N, O, Na, Mg, Al, Si, P, S, K, Ca, Ti, TiII, V, Cr, Mn, Fe, Co, and Ni.