The APOGEE red-clump catalog: Precise distances, velocities, and
  high-resolution elemental abundances over a large area of the Milky Way's
  disk
  The Sloan Digital Sky Survey III's Apache Point Observatory Galactic
Evolution Experiment (APOGEE) is a high-resolution near-infrared spectroscopic
survey covering all of the major components of the Galaxy, including the
dust-obscured regions of the inner Milky Way disk and bulge. Here we present a
sample of 10,341 likely red-clump stars (RC) from the first two years of APOGEE
operations, selected based on their position in
color-metallicity-surface-gravity-effective-temperature space using a new
method calibrated using stellar-evolution models and high-quality
asteroseismology data. The narrowness of the RC locus in
color-metallicity-luminosity space allows us to assign distances to the stars
with an accuracy of 5 to 10%. The sample extends to typical distances of about
3 kpc from the Sun, with some stars out to 8 kpc, and spans a volume of
approximately 100 kpc^3 over 5 kpc <~ R <~ 14 kpc, |Z| <~ 2 kpc, and -15 deg <~
Galactocentric azimuth <~ 30 deg. The APOGEE red-clump (APOGEE-RC) catalog
contains photometry from 2MASS, reddening estimates, distances, line-of-sight
velocities, stellar parameters and elemental abundances determined from the
high-resolution APOGEE spectra, and matches to major proper motion catalogs. We
determine the survey selection function for this data set and discuss how the
RC selection samples the underlying stellar populations. We use this sample to
limit any azimuthal variations in the median metallicity within the ~45
degree-wide azimuthal region covered by the current sample to be <= 0.02 dex,
which is more than an order of magnitude smaller than the radial metallicity
gradient. This result constrains coherent non-axisymmetric flows within a few
kpc from the Sun.
