New Sky Atlas Opens to First Pages

SAN DIEGO--Astronomers unveiled their "first light" pictures from the $77 million Sloan Digital Sky Survey (ScienceNOW, 29 May) today at a meeting of the American Astronomical Society (AAS) here. The images, unrolled dramatically as a 30-foot scroll, are just a fraction of a detailed survey of the sky that will take up to 7 years to complete and will eventually record about 100 million objects in the sky, including objects 40 times fainter than those in the last thorough photographic atlas of the heavens, the Palomar All-Sky survey from the 1950s.

Shown at left is a tiny part of that scroll, a patch of sky in the constellation Serpens. The bright galaxy NGC 6070 (upper left), ablaze with the blue light of young stars, lies more than 100 million light-years away from Earth. This picture represents just 0.02% of the data collected in the survey's first 7 minutes on the night of 9 May, according to graduate student Constance Rockosi of the University of Chicago in Illinois. Data flow in through a special camera attached to the survey's 2.5-meter telescope at Apache Point Observatory, New Mexico, at the rate of 8.5 megabytes per second, Rockosi says.

Astronomers will use the survey and its accompanying spectra--which reveal redshift and thus distance--of 1 million galaxies and 100,000 quasars to create the most comprehensive three-dimensional map of large-scale structure in the universe, says astronomer Neta Bahcall of Princeton University in New Jersey. Further, researchers will turn to the survey for decades as a "permanent digital encyclopedia of the sky," predicts astronomer Bruce Margon of the University of Washington, Seattle.

AAS President-elect Robert Gehrz of the University of Minnesota, Minneapolis, had this reaction to the scroll: "On behalf of the AAS, wow! This is one of the outstanding technological achievements of modern astronomy." The eventual size of the Sloan Survey's database, Gehrz says, will rival the contents of the Library of Congress.