Michael Braukus Headquarters, Washington, D.C. May 28, 1991 (Phone: 202/453-1549 ) Jim Sahli Marshall Space Flight Center, Huntsville, Ala. (Phone: 205/544-0034 ) RELEASE: 91-81 NASA SCIENCE INSTRUMENT OBSERVING GAMMA-RAY BURSTS The Burst and Transient Source Experiment (BATSE), one of four instruments on NASA's Gamma Ray Observatory, is detecting gamma-ray bursts with a greater sensitivity than previous instruments, according to the principal investigator speaking at an American Astronomical Society conference in Seattle, Wash. "We are detecting gamma-ray bursts at a higher rate and in much greater detail than ever before," said Dr. Gerald Fishman, a NASA astrophysicist at the Marshall Space Flight Center, Huntsville, Ala., and principal investigator for BATSE. "Gamma-ray bursts are being observed by BATSE at the rate of approximately five per week or an extrapolated rate of about 250 per year. Previously, gamma-ray bursts were seen by the KONUS Soviet experiment aboard the Venera spacecraft at a rate of about 80 per year," said Fishman. "The large area and high sensitivity of the BATSE detectors will permit more detailed studies of the gamma-ray bursts which, in turn, may help to explain the cause of the still-unexplained bursts," he said. "Pulsing sources, solar flares and other high-energy objects also are being observed routinely with a high sensitivity. The data coming back are of high quality and quantity, and we expect that a large number of high-energy astrophysicists will be kept busy analyzing and interpreting the data for years," he said. Dr. Fishman told colleagues that gamma-ray bursts, which are random, powerful flashes of gamma-rays coming from different locations of the sky, are one of the least understood phenomena in astrophysics and with BATSE we can learn more about them over the next few years. -more- -2- The analysis of the information gained by the BATSE instrument from the gamma-ray bursts is being conducted by scientists from the Marshall center, the University of Alabama in Huntsville, the Universities Space Research Association, the University of California at San Diego, and the Goddard Space Flight Center, Greenbelt, Md. In addition, 26 guest investigator scientists from the United States and Europe also will participate in this initial phase of the data analysis. "The scientists at Marshall continue to work 7 days a week using numerous computer programs to catalog, store and then analyze data from BATSE. "Over a six month period, a pattern will begin to emerge and we will begin to learn more about the distribution, strength and direction of these mysterious gamma-ray bursts," said Fishman. After a month-long activation and checkout period, the Gamma Ray Observatory began routine science operations on May 16. The observatory is managed by the Goddard Space Flight Center for NASA's Office of Space Science and Applications, Washington, D.C. - end -