APOGEE: The apache point observatory galactic evolution experiment

APOGEE is a large-scale, NIR, high-resolution (R ∼ 20 000) spectroscopic survey of Galactic stars. It is one of the four experiments in SDSS-III. Because APOGEE will observe in the H band, where the extinction is six times smaller than in V, it will be the first survey to pierce through Galactic dust and provide a vast, uniform database of chemical abundances and radial velocities for stars across all Galactic populations (bulge, disk, and halo). The survey will be conducted with a dedicated, 300-fiber, cryogenic, spectrograph that is being built at the University of Virginia, coupled to the ARC 2.5-m telescope at Apache Point Observatory. APOGEE will use a significant fraction of the SDSS-III bright time during a three-year period to observe, at high signal-to-noise ratio (S/N > 100), about 100000 giant stars selected directly from 2MASS down to a typical flux limit of H < 13. The main scientific objectives of APOGEE are: (1) measuring unbiased metallicity distributions and abundance patterns for the different Galactic stellar populations, (2) studying the processes of star formation, feedback, and chemical mixing in the Milky Way, (3) surveying the dynamics of the bulge and disk, placing constraints on the nature and influence of the Galactic bar and spiral arms, and (4) using extensive chemodynamical data, particularly in the inner Galaxy, to unravel its formation and evolution.