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Gamma-ray bursts: upping the ante.

Like cosmic flashbulbs, gamma-ray bursts are intense flares that last just a few seconds and then vanish, usually forever. The origins and properties of these celestial bursts have remained a mystery since their discovery 20 years ago.

Early results from NASA's Gamma Ray Observatory add a new twist to the puzzling phenomenon. Since the April 5 launch of this orbiting observatory, its detectors have recorded about one gamma-ray burst per day -- a rate higher than that detected by any other satellite, says Gerald J. Fishman of NASA's Marshall Space Flight Center in Huntsville, Ala.

Fishman explains that the eight detectors placed around the craft's perimeter, where they monitor bursts throughout the sky, form a larger collecting area and thus can detect fainter bursts than detectors on other satellites. The study, called the Burst and Transient Source Experiment (BATSE), indicates that gamma-ray bursts occur randomly and have a widespread distribution, Fishman says. He adds that the duration of gamma bursts detected by BATSE has varied from seconds to hundredths of seconds -- suggesting that the flashes may have several different types of sources.

Other scientists have recently analyzed gamma-ray data recorded by three French-Soviet satellites. In the May 23 NATURE, researchers led by J.L. Atteia of the Center for the Study of Space Radiation in Toulouse, France, report that the distribution of gamma-ray bursts concentrates in the plane of our galaxy and falls off with distance -- a possible sign, they say, that the bursts originate in the Milky Way.

Over the next six months, says Fishman, BATSE may detect enough bursts to indicate their origin.
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Title Annotation:Gamma Ray Observatory data
Author:Cowen, Ron
Publication:Science News
Date:Jun 8, 1991
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