The Data Reduction Pipeline for the Apache Point Observatory Galactic
  Evolution Experiment
  The Apache Point Observatory Galactic Evolution Experiment (APOGEE), part of
the Sloan Digital Sky Survey III, explores the stellar populations of the Milky
Way using the Sloan 2.5-m telescope linked to a high resolution (R~22,500),
near-infrared (1.51-1.70 microns) spectrograph with 300 optical fibers. For
over 150,000 predominantly red giant branch stars that APOGEE targeted across
the Galactic bulge, disks and halo, the collected high S/N (>100 per
half-resolution element) spectra provide accurate (~0.1 km/s) radial
velocities, stellar atmospheric parameters, and precise (~0.1 dex) chemical
abundances for about 15 chemical species. Here we describe the basic APOGEE
data reduction software that reduces multiple 3D raw data cubes into
calibrated, well-sampled, combined 1D spectra, as implemented for the
SDSS-III/APOGEE data releases (DR10, DR11 and DR12). The processing of the
near-IR spectral data of APOGEE presents some challenges for reduction,
including automated sky subtraction and telluric correction over a 3 degree
diameter field and the combination of spectrally dithered spectra. We also
discuss areas for future improvement.
