A collaboration of researchers from around the world has just made the largest ever digital color image of the sky available to the scientific community and the public. The image has been put together using photographic information obtained from a powerful digital camera mounted on a telescope in New Mexico and spectroscopic surveys executed through several programs. The Sloan Digital Sky Survey has presented the enormous sky map to the 217th annual meeting of the American Astronomical Society in Seattle.

Over the last ten years or so, the 138 megapixel Sloan Digital Sky Survey (SDSS) imaging camera – mounted on the back of a dedicated 2.5 meter telescope at the Apache Point Observatory in New Mexico – has been snapping millions of 2.8 megapixel images of sections of the heavens. Around 470 million astronomical objects, including asteroids, stars, galaxies and distant quasars, have so far been discovered using the data released by SDSS.

The latest data release is the first from the SDSS-III project and the eighth since the SDSS collaborative effort began. It also marks the retirement of this imaging camera, which has managed to record over 14,000 square degrees of the Northern celestial sphere. It will now become part of the permanent collection at the Smithsonian in recognition of its contributions to the field of astronomy. The five color, one thousand billion pixel map of the sky created from the camera's photographic data is said to require 500,000 high definition televisions to view it at full resolution.

The researchers have started using the enormous image to undertake new surveys over the past 12 months or so which rely on spectra, a technique that uses instruments to spread the light from a star or galaxy into its component wavelengths. Spectroscopic surveys are undertaken to measure distances to far-away galaxies, and to discover galactic structure and chemical evolution. Such information will help to create detailed three-dimensional maps that show how galaxies are distributed in space.

Data Release 8 incorporates the final results of another project at SDSS, the Sloan Extension for Galactic Understanding and Exploration survey. This survey looked at the properties and motions of hundreds of thousands of stars in the Milky Way which, when added to earlier survey information, brings the total spectrograph coverage to over 9,000 square degrees.

Further surveys at SDSS will run until 2014, including the Baryon Oscillation Spectroscopic Survey and the Multi-object APO Radial Velocity Exoplanet Large-area Survey. More information on the work of SDSS-III can be found on the project website.

Data Release 8 of the SDSS has been submitted for publication in the Astrophysical Journal Supplements.

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