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Digital Telescope to Map 25% of the Sky : Astronomy: Technology similar to that in home video cameras will be used to scan the heavens for light particles and store them on highly sensitive computer chips.


BALTIMORE — A new telescope that uses the same chips found in many home video cameras will provide the most extensive survey ever of about 25% of the sky.

Researchers hope that the Sloan Digital Sky Survey scheduled to begin late this year or early next year will reveal clues about the structure and beginning of the universe.

The project, which will be conducted at Apache Point Observatory near Sunspot, N.M., is a joint collaboration of researchers from Johns Hopkins University, Princeton University and five other institutions, according to Edwin Turner, an astrophysics professor at Princeton.

Researchers expect the survey will take five years to complete.

Unlike home telescopes that allow the user to view one portion of the heavens with the naked eye, the Sloan Digital Telescope will "plow" the skies. The telescope will scan long, thin strips of the night sky for photons, the actual particles of light.

Light focused by the telescope will land on a bank of 30 chips, and the information recorded by the chips will be stored as digital computer information, Turner said.

Although the chips in the telescope resemble those found in home video cameras, those in the telescope have been modified to much higher sensitivity. Four of the devices in the giant, 200-inch Hale telescope in California can detect a lighted cigarette 700 miles away. Other variations are also used in spy satellites.

When finished, the researchers will have images in five different colors, which scientists can use to determine the characteristics of various stars, quasars and other galactic objects. They will also have a useful reference tool that can be stored on computer disks or retrieved from a computer network.

"We'll be imaging approximately a quarter of the whole sky. In that area there are almost a hundred million galaxies; to have that kind of multicolor data for such a large area is going to be an incredible resource," said Marc Postman, an associate professor of astronomy at Johns Hopkins University.

The survey is one of several in the planning stages that should provide a broad overview of the universe, said Stephen Strom, chairman of astronomy at the University of Massachusetts.

"It will not only yield important scientific results on its own, but will provide a very important tool for selecting sources of study with the new generation of telescopes that are coming on line," he said.

While the Sloan survey will measure the visible light spectrum, others will deal with infrared and other non-visible light, Strom said.

The other institutions involved in the Sloan project are the University of Chicago, the University of Washington, the Institute for Advanced Studies at Princeton, Fermilab in Illinois, the Naval Research Lab and a group of Japanese astronomers, Turner said.

The survey will also help scientists get a better idea of what the universe looks like and the motion of various galaxies.

"It's like being an ant crawling around on a piece of art. Understanding this large-scale structure we hope will be a key to how the universe formed and evolved," Turner said.

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