Three spacecraft, including one at Mars, teamed up to make a unique deep-space observation of a colossal energy burst. The Earth-orbiting satellite BeppoSAX, the solar-spying Ulysses, and NASA's Mars Odyssey combined to detect a brief yet intense gamma ray burst.
The trio of observations was the first of its kind. With three observations, scientists can "triangulate" the location and distance of an object. The accuracy of the measurements becomes greater when the distance between the crafts grows.
After the location was pinpointed, the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory in Chile was employed to capture visible-light images of the event. When the image was taken, less than two days after the initial detection, just one percent of the radiation remained.
The Very Large Telescope in Chile found measured the redshift of optical light coming from the source, from which its distance was found.
Gamma rays have been studied since the 1960s, but where they come from and their role in the universe has been difficult to determine. The explosions can last for only a millisecond to a few minutes, and come from all parts of the sky. They are thought to originate mostly beyond our galaxy and to temporarily outshine the rest of the universe in gamma rays.
Astronomers have been challenged to get more than one eye in the sky trained on a single burst.
Gamma rays are so powerful that if generated nearby, they would penetrate steel and irradiate everything to extinction. Luckily, the newly observed burst came from more than 4 billion light-years away. That's the closest gamma-ray burst ever detected, researchers said.
"It turns out that weak bursts can be close, and strong bursts can be very distant; this means that we are probably observing emission which is beamed," said Kevin Hurley from the University of California at Berkeley and principal investigator for the gamma-ray burst experiment on Ulysses.
"If we happen to be right in the beam, the burst will look strong, regardless of its distance."
Since the discovery in recent years that exploding stars called supernovae are one source of gamma rays, many gamma-ray sources have been pinpointed after a burst, since astronomers learned they could then look for visible light and other radiation. But many go undetected. Scientists now believe that one detonates somewhere in the sky every minute or so. And it is unclear whether supernovas are the only source of them.
Further study of these explosions will help astronomers understand the first moments just after the Big Bang, because some gamma-ray bursts occur near the expanding edge of the universe. Radiation coming from so far away should reveal conditions as they were very near the beginning of time.
Scientists said future efforts to study gamma-ray bursts would involve attempts to coordinate telescope imaging immediately after the initial detection.
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