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University of Chicago News Office
Chicago, Illinois

Contact:
Steve Koppes, (773) 702-8366, s-koppes{at}uchicago.edu

April 10, 2003

Astrophysicists scurry to make follow-up observations of
'nearby' cosmic explosion 

The birth cry of a black hole has startled University of
Chicago astrophysicists and their colleagues who operate
a NASA satellite that searches for gamma-ray bursts, the
most powerful explosions in the universe.

Now the Chicago astrophysicists are rushing to make
follow-up observations of the event with the
Astrophysical Research Consortium 3.5-meter telescope
at the Apache Point Observatory in New Mexico. They
also are drowning in information provided by amateur
astronomers.

"This event is so bright that hundreds of amateur
astronomers have been observing it, recording their data
and providing it to us," said Don Lamb Jr., the Louis
Block Professor in Astronomy & Astrophysics at the
University of Chicago and Mission Scientist for the
HETE-2 mission. "We can't keep up with it."

Gamma-ray bursts signal the birth of black holes, which
are objects so dense that no light can escape their
gravitational pull. The burst detected by NASA's High
Energy Transient Explorer-2 satellite on the morning
of March 29 was one of the brightest and closest every
reliably documented, Lamb said.

"This could nail the connection between gamma-ray bursts
and core-collapse supernovae," he said. This type of
supernova, or exploding star, results in the formation
of a black hole. 

The data suggest that the supernova explosion was very
non-spherical, which supports new ideas about how core
collapse supernovae happen. "This is absolutely going
to change everything," Lamb said. 

The burst, designated GRB 030329, lasted for more than
30 seconds. Only two other gamma-ray bursts have shined
more brightly in the 30 years since the phenomenon was
discovered, Lamb said. Even its afterglow shined more
than 10,000 times brighter than its host galaxy two
hours after the burst occurred. 

The explosion occurred approximately 2 billion light
years from Earth, too distant to pose a threat, but
two and a half times closer than the next-closest
burst for which scientists have reliable measurements.

HETE-2 is pinpointing the positions on the sky of 25
gamma-ray bursts annually. "The chance of a burst
this near and this bright happening is one in a few
thousand," Lamb said. "We likely won't see anything
like this again."

Collaborating with Lamb on HETE-2 are the University
of Chicago's Carlo Graziani, Senior Research Associate
in Astronomy & Astrophysics, and Timothy Donagy, a
graduate student in Physics. Collaborating with him
on the follow-up observations are Donald York, the
Horace B. Horton Professor in Astronomy & Astrophysics
at the University of Chicago, and John Barentine and
Russet McMillan, Observing Specialists at Apache Point
Observatory.

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