The Sloan Extension for Galactic Understanding and Exploration (SEGUE) Survey obtained ≈240,000 moderateresolution (R ∼ 1800) spectra from 3900 Å to 9000 Å 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 σ (RV) ∼ 4 km s −1 at g < 18, degrading to σ (RV) ∼ 15 km s −1 at g ∼ 20. For stars with signal-to-noise ratio >10 per resolution element, stellar atmospheric parameters are 4377 4378 YANNY ET AL.Vol. 137 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 (σ (g, r, i) ∼ 2%), (σ (u, z) ∼ 3%) and astrometry (≈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.
With the Sixth Data Release of the Sloan Digital Sky Survey, the imaging of
the Northern Galactic Cap is now complete. The survey contains images and
parameters of roughly 287 million objects over 9583 deg^2, and 1.27 million
spectra of stars, galaxies, quasars and blank sky (for sky subtraction)
selected over 7425 deg^2. This release includes much more extensive stellar
spectroscopy than previously, and also includes detailed estimates of stellar
temperatures, gravities, and metallicities. The results of improved photometric
calibration are now available, with uncertainties of roughly 1% in g, r, i, and
z, and 2% in u, substantially better than the uncertainties in previous data
releases. The spectra in this data release have improved wavelength and flux
calibration, especially in the extreme blue and extreme red, leading to the
qualitatively better determination of stellar types and radial velocities. The
spectrophotometric fluxes are now tied to point spread function magnitudes of
stars rather than fiber magnitudes, giving a 0.35 mag change in the
spectrophotometric flux scale. Systematic errors in the velocity dispersions of
galaxies have been fixed, and the results of two independent codes for
determining spectral classifications and redshifts are made available.
(Abridged)Comment: 21 pages with 8 color figures. ApJS, in press. Minor modifications
from previous versio
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