GRB 990510
Credit: X-ray: L. Piro and the BeppoSax Team; Optical: J. Kaluzny (Warsaw U. Obs.) et al., 1-meter Swope Telescope

Pinpointing an Elusive Burst

Gamma-Ray bursts are brief flashes of very high energy radiation; though discovered by US military satellites (designed to detect high energy evidence of Soviet nuclear tests) in the seventies, their origin remained a mystery for more than 20 years, due to the fact that gamma-ray detectors could not image the source of the bursts. A breakthrough came with the detection of an X-ray "afterglow" of a gamma-ray burst by the BeppoSAX satellite in 1997. Another breakthrough came with the detection of an "optical" afterglow of a gamma-ray burst which occurred on May 5, 1999. An X-ray afterglow from the "May Fifth" burst was detected by BeppoSAX, which transmitted the approximate coordinates of the X-ray source to astronomers all around the world. Astronomers trained their telescopes on this location, and an object was detected which faded rapidly in brightness. The upper image above shows the BeppoSAX image of the X-ray afterglow; the lower image shows a photo of the region around the X-ray source, which clearly shows an object which faded noticeably in brightness from May 11 to May 12. The detection of this source by ground-based telescopes allowed astronomers to pinpoint the location of the gamma-ray burst source; subsequent observation with the Hubble Space Telescope showed the source to be located in a distant galaxy and that the absolute power of the burst to be enormous - about as bright as 10 billion Milky Way Galaxies!

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Page Author: Dr. Michael F. Corcoran
Last modified March 18, 2002