Gamma-ray bursts - flashes of intense radiation in space that are often just seconds long-were accidentally discovered in the 1960's by satellites built to monitor nuclear bomb explosions. They have been one of the leading astrophysical mysteries ever since. A 6 minute video "Astro Bulletin" entitled "Gamma-Ray Bursts: Flashes in the Sky" (flash, quicktime), prepared by the American Museum of Natural History in New York, introduces the scientists and instruments working to unravel the origins of gamma-ray bursts. It highlights Swift, NASA's burst-detecting satellite, and PAIRITEL, one of a fleet of ground-based telescopes that point toward a gamma-ray burst in response to Swift's alert to capture the afterglow before it fades. Astrophysicists at Penn State (including faculty members Dave Burrows, Peter Meszaros, and John Nousek) and other institutions are analyzing these afterglows to understand what causes the most powerful explosions known. For more information, see the American Museum of Natural History Science Bulletins.