SEGUE: A SPECTROSCOPIC SURVEY OF 240,000 STARS WITH g=14-20

The Sloan Extension for Galactic Understanding and Exploration (SEGUE) Survey obtained approximate to 240,000 moderate-resolution (R similar to 1800) spectra from 3900 angstrom to 9000 angstrom of fainter Milky Way stars (14.0 < g < 20.3) of a wide variety of spectral types, both main-sequence and evolved objects, with the goal of studying the kinematics and populations of our Galaxy and its halo. The spectra are clustered in 212 regions spaced over three quarters of the sky. Radial velocity accuracies for stars are sigma(RV) similar to 4 km s(-1) at g < 18, degrading to s(RV) similar to 15 km s(-1) at g similar to 20. For stars with signal-to-noise ratio > 10 per resolution element, stellar atmospheric parameters are estimated, including metallicity, surface gravity, and effective temperature. SEGUE obtained 3500 deg(2) of additional ugriz imaging (primarily at low Galactic latitudes) providing precise multicolor photometry (sigma(g, r, i) similar to 2%), (sigma(u, z) similar to 3%) and astrometry (approximate to 0 ''.1) for spectroscopic target selection. The stellar spectra, imaging data, and derived parameter catalogs for this survey are publicly available as part of Sloan Digital Sky Survey Data Release 7.