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 Bo¿tes. 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.
Image: HUBBLE SPACE TELESCOPE, Space Telescope Science Institute
Astronomers were also able to obtain optical images of the gamma-ray burst. Just 20 seconds after the first alert had sounded, a robotic optical telescope in Los Alamos, N.M., had zeroed in with four wide-field cameras. After other researchers had identified the burst's precise position, the Los Alamos group discovered that its early images had captured a bright (9th magnitude) but rapidly fading star at that exact location.
The next night the mighty Keck II, the 10-meter monster telescope that sits atop the Mauna Kea volcano in Hawaii, swung into action. With its huge light-gathering surface, it measured the object's redshift and determined that the gamma-ray burst had originated halfway across the universe.
That's when champagne corks started popping. For something so distant to shine so intensely in our sky, it must be incredibly bright at its source. In fact, whatever produced the gamma rays had, for a while at least, been the brightest object ever identified. Without a doubt, astronomers had made a major discovery. And now they aim to get amateurs in on the fun.
Why amateurs? Because the BATSE team members know that had the Beppo-SAX satellite been looking elsewhere that night, astronomers never would have been able to direct ground-based telescopes to measure the object's magnitude and distance. And even then it took precious hours to fix a position of the rapidly changing object.
A better system would consist of numerous observers looking inside the BATSE-identified region within minutes of the event's detection. With enough people, chances are that someone would quickly find the new object and report in so that other observations could be set in motion. Thus, the BATSE team has wanted to create an international network of both professionals and amateurs who will be on standby to help when BATSE detects a gamma-ray burst
Graph: JOHNNY JOHNSON, NASA