Key points are not available for this paper at this time.
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 10 per resolution element, stellar atmospheric parameters are estimated, including metallicity, surface gravity, and effective temperature. SEGUE obtained 3500 deg² of additional 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 parameter catalogs for this survey are publicly available as part of Sloan Digital Sky Survey Data Release 7.
Yanny et al. (Tue,) studied this question.