The Amateur Scientist; February 2000; Scientific American Magazine; by Carlson; 2 Page(s)

Sometimes it's better to be lucky than good. On January 23, 1999, a satellite-based instrument called the Burst and Transient Source Experiment (BATSE) detected a bright flash of gamma rays coming from the constellation Bootes. For years, astronomers had caught sight of such gamma-ray bursts several times a week in every part of the sky [see "Gamma-Ray Bursts," by Gerald J. Fishman and Dieter H. Hartmann; Scientific American, July 1997]. But precious little was known about these sources of incredible energy-how do they form and from where do they originate?-because they are so fleeting. They rarely shine longer than a few minutes (some exist for only a tiny fraction of a second), providing little time for astronomers to bring a variety of instruments to bear. Indeed, even though that night's event was quite bright and lasted almost two minutes, BATSE could only localize the source to a disk on the sky about four full moons wide.

Enter Lady Luck. At the moment the burst went off, another satellite called Beppo-SAX just happened to be imaging the same section of sky, using a wide-field camera for x-rays (radiation of somewhat lower frequency than gamma rays). Within six hours of receiving a detection alert from BATSE via e-mail, scientists had fixed the precise position of a bright x-ray source that was within the BATSE-identified region but that had not been there before.