Gamma Ray Burst
Page from Worth Hill Observatory
Gamma-ray bursts are perhaps one of the most intriguing
discoveries of modern astronomy, however the story is just unfolding but
with rapid communications these days the amateur has an opportunity
to have a go and get envolved in this exciting field. Gamma ray bursts
are now known to be the most energetic events in the known universe, and
can outshine the rest of the universe for a couple of seconds or so. The
first Gamma ray bursts were detected in the 1960's by US spy satellites
which were designed to search for violations of the nuclear test ban treaty,
but it wasn't until the early 1970's that their cosmic origin was
made public.
Ever since their initial discovery, there has
been a quest to discover a counterpart to a gamma-ray burst in any other
wavelength region, the so called "afterglow" or "optical transient". There
have been various satellite missions launched to investigate them, but
the most successful in recent years is The HETE (High Energy Transient
Explorer) satellite. The prime objective is the precise localization and
rapid follow-up observation of gamma-ray burst locations by on-board UV
detectors and observatories on the ground. It was as a result of a HETE
positive observation of a GRB that I was prompted to have a go at imaging
the "afterglow" of such a burst as a result of this circular from
"The Astronomer".
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| GRB 021004
Nial Tanvir, Department of Physical Sciences, University of Hertfordshire, Hatfield, reports that this well placed GRB went off about lunch time today, and already has an afterglow identified. The coordinates are: RA 00h 26m 54.4s DEC +18 55' 41" (2000) There is a (postscript) finding chart at: http://www.astro.caltech.edu/~derekfox/grb021004/ Nial adds that from the decay rate, one would
expect it to still be
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With a beautiful clear sky and currently no moon,
I plotted the coordinates and realised that this GRB was very well placed
just east of the Square of Pegasus, and on the meridian at midnight. As
it was reported to be of mag 18 I realised that I had to go for 10 or 20
x40 sec exposures to get any worth while images. Here is the series of
images I obtained approximately 8 hours after the outburst detection.
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Together with four other U.K. amateurs this observation was one of the first UK based optical detection of a GRB. Take a look at the "TA" GRB page here for other images. |
| For faint objects it sometimes
helps to
display them as a negative or false colour image: |
 |
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Finally resampled, cropped and contrast stretched to give a larger image scale: |
March 30th 2003
GRB 030329 another exceptionally bright OT of a GRB discovered by HETE and recorded here a day after discovery. This object appeared at mag 12 at discovery and to date has been the only OT of a GRB to be seen visually with a small telescope. It was imaged here some 36 hours after discovery having now faded to mag 16.5. This is a 10x20 sec exposure in dark sky conditions.
April 2nd 2003
This GRB remains exceptionally bright - 4 days post discovery it is still recorded here at mag 18
April 7th 2003
GRB now faded to the limit of detectability approaching mag +19
