The Sixth Data Release of the Sloan Digital Sky Survey

TL;DR

The Sixth Data Release of SDSS provides extensive imaging and spectroscopy data with improved calibration, covering millions of celestial objects and offering better stellar and galaxy parameter estimates for astronomical research.

Contribution

This release offers the most extensive stellar spectroscopy data to date, with enhanced calibration and more accurate stellar and galaxy parameters compared to previous SDSS data releases.

Findings

Increased number of stellar spectra with detailed parameters

Improved photometric and spectroscopic calibration accuracy

Fixes systematic errors in galaxy velocity dispersions

Abstract

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)