Hunting Gamma-Ray Bursts at Palomar Observatory
One of the
universe’s most mysterious and explosive events is the phenomenon
known to astronomers as a Gamma-Ray Burst (GRB). They are briefly
bright enough to be visible billions of light years away. They
are difficult to study as they are short lived and take place at
seemingly random locations and times. To achieve an understanding
of what exactly a GRB is and why they occur, astronomers need
to act quickly to pin down their exact location and observe them
while they are exploding.
The existence of UCSD’s
High Performance Wireless Research and Education Network (HPWREN)
has been absolutely critical to GRB research at the Palomar Observatory.
HPWREN’s microwave link has increased the Observatory’s
bandwidth by 28 times. This allows remote astronomers to rapidly
point the newly automated telescopes and their high performance
digital cameras in real time to catch these and other elusive events.
A recent example illustrates how this works. Gamma rays do not penetrate our atmosphere, so must first be detected by an orbiting satellite. The satellite detects the explosion but can only pin down its location to a relatively large region of the sky, about twice the diameter of the full moon. Within seconds, it sends an email with this location to all interested observers. In October of 2002, GRB021004 was detected by the HETE satellite. Upon receiving the announcement Caltech astronomer Derek Fox used the HPWREN microwave link to seize control of the wide-field 48-inch Samuel Oschin Telescope and take an image of the field with the JPL/NEAT CCD camera just 9 minutes after the explosion began. The microwave link allowed the data to be rapidly transferred to Derek at Caltech. Analyzing it, he was able to pin down the exact location of the GRB (see figure), which he announced to astronomers world-wide only three hours after the burst occurred. This enabled the details of the afterglow's fading behavior to be observed around the world with unprecedented precision.
The study of this and more recent gamma-ray busts are
starting to provide a picture of what may be their cause - the explosion of a
massive star during the creation of a black hole in galaxies far away – a
particularly energetic example of a supernova explosion.
Modern electronic cameras used on astronomical telescopes generate large volumes of data. The new QUEST camera on the Samuel Oschin Telescope at Palomar has 161 million pixels, making it one of the largest and most capable digital cameras in the world. HPWREN gives the Observatory the bandwidth to allow astronomers to control and process data from these powerful facilities quickly. Early astronomy concentrated on moving and transient sources visible to the naked eye. The advent of large telescopes and long exposures enabled us to observe faint but mainly unchanging objects. Modern rapid-response facilities enable us to observe the exciting but difficult realm of very faint moving and transient objects.