DURHAM, N.H. -- University of New Hampshire
scientists, including one very sleepy graduate student,
reacted within minutes to analyze data from the
first-ever optical images of a gamma ray burst.
NASA reported earlier this week its researchers had managed to take the first optical images of one of the most powerful explosions in the universe as it was occurring on Saturday, Jan. 23. Gamma ray bursts produce more energy in a very short period than the rest of the entire universe combined.
UNH graduate student C. Alex Young's pager went off at 4 a.m. Jan. 23. "My first reaction was, 'Hey, this is pretty big,' but I was pretty sleepy," admits Young, a Georgia native who completes his doctoral studies in physics this May.
Because such bursts occur with no warning and typically last for just a few seconds, quick detection by orbiting spacecraft and instant notification to astronomers are critical in order to catch the bursts in the act.
The gamma-ray-burst detectors of the Burst and Transient Source Experiment (BATSE) onboard NASA's orbiting Compton Gamma Ray Observatory detected the beginning of a bright gamma ray burst. As the burst was still in progress, computers determined a rough location and radioed the position to the Gamma Ray Burst Coordinates Network (GCN), based at NASA's Goddard Space Flight Center, Greenbelt, MD. The position was immediately forwarded via the GCN to astronomers at ground based observatories throughout the world.
The COMPTEL experiment on the Compton Gamma-Ray Observatory, operated from the UNH Institute for the Study of Earth, Oceans and Space, is set up to rapidly respond to major gamma-ray burst events. Triggered by data from the BATSE experiment, the COMPTEL data was being automatically processed and analyzed at UNH within minutes of the event.
At the same time, a message was sent by beeper to UNH personnel, including Young, who immediately went to his computer to check on the status of the processing. The initial effort failed to yield any results. Subsequent analysis by Young and Dr. Alanna Connors (a former UNH staff member who still keeps tab on COMPTEL from Wellesley College) led to a position for the burst that was distributed by e-mail to observers around the world.
For sufficiently intense gamma-ray bursts within its field-of-view, COMPTEL is able to generate an image of the event in the light of medium-energy gamma-rays, explains Mark McConnell, UNH research associate professor of physics. Although well outside the normal field-of-view, the burst was successfully imaged by COMPTEL. Only the enormous instensity of the gamma-ray emission made it possible for COMPTEL to generate an image and report a position.
Just 22 seconds after the burst, the Robotic Optical Transient Search Experiment (ROTSE) in Los Alamos, NM, operated by a team led by Dr. Carl Akerlof of the University of Michigan, was in position and took images of the patch of sky where the burst was reported. Their equipment is assembled from 35 mm camera lenses and parts culled from the amateur astronomy market. The first picture showed a brightening new star within the sky region where the burst was reported.
Five seconds later, the burst achieved peak brightness, reaching 9th magnitude, about 16 times fainter than the human eye can see, but easily visible in an amateur telescope. Within eight minutes of the initial detection, the burst had faded by a factor of 100 below its maximum brightness. "I was amazed," Akerlov said. "At best, we expected something really dim optically, at the limit of our sensitivity. Instead we found a whopper."
"If this burst had originated in the Milky Way Galaxy, it would have lit up the night sky," said Dr. Alan Bunner, Director of NASA's Structure and Evolution of the Universe science theme at NASA Headquarters.
The data obtained at UNH from the COMPTEL experiment, says McConnell, represents the highest energy emissions observed fromn this gamma-ray burst. "As such, these data will provide important constraints on the interpretation of the observations, observations which already are providing great insights into one of the most fundamental mysteries in all of astrophysics."
FOR IMMEDIATE RELEASE
C. Alex Young can be contacted at 862-4385 or at 742-5048. Mark McConnell can be reached at 862-2047 or 659-7625.
By Carmelle Druchniak
UNH News Bureau