While most of North America awakened to an otherwise uneventful Tuesday morning, Marshall's Burst and Transient Source Experiment (BATSE) aboard NASA's Compton Gamma-Ray Observatory detected the brightest gamma-ray burst in its five and a half year mission. Shortly after 6:42 am CDT on September 24, 1996, the eight detectors that comprise the BATSE experiment were bombarded with high energy gamma-radiation in the form of a colossal cosmic gamma-ray burst. The image below shows a plot of the burst's brightness as a function of time in two of the BATSE detectors.
Discovered by accident in the late 1960's, gamma-ray bursts are short-lived
blasts of gamma radiation that, if your
eyes could detect them, might look like giant flashbulbs going off in the
sky. Their locations in the sky are completely random, and their time of
occurrence is not predictable. Once thought to be located in our own Milky
Way Galaxy, most astronomers now believe that the bursts are actually located
at distances in excess of hundreds of millions of light-years, or near the
edge of the visible universe. At the intensity and distance that these bursts
are observed, they have to release as much energy in tens of seconds as
the Sun will produce in its entire ten-billion-year lifetime.
BATSE detects bursts at a rate of approximately one per day. However, this particular burst is by far the most intense that BATSE has ever observed. "This makes the event particularly interesting to scientists, as bursts of this brightness are exceedingly rare and may contain information about the sources that cannot be extracted from the weaker events," said Dr. Charles Meegan of the BATSE Science Team. "We're just now beginning to look at the data in detail and determine what other spacecraft were able to see the burst. This will, in part, help us to obtain a more accurate location in the sky for the event," Meegan added.
The Compton Observatory, containing BATSE, was launched aboard the space-shuttle Atlantis on April 5, 1991 on STS-37. Since its activation a few days later, BATSE has observed over 1700 cosmic gamma-ray bursts, more than all previous experiments combined. It continues today, monitoring the heavens for gamma-ray bursts, as well as providing information on such exotic objects as neutron stars, binary pulsars, active galactic nuclei, and other transient gamma-ray sources.