Summary of Early Observations
Credit:
NASA,
Compton Gamma Ray Observatory,
BATSE
Distribution of Gamma Ray Bursts
On average, about one every day the
gamma-ray sky lights up with a
spectacular explosion.
The above map was created by Robert Nemiroff and
represents the entire sky
in galactic coordinates. In this map,
spot size is proportional
to peak flux during the gamma ray burst (which can be as short as a few seconds)
and spot color indicates the average energy,
with the more
blue dots being highest in energy.
The map shows the positions of over 800 gamma ray bursts
detected by the
BATSE
instrument on NASA's
Compton Gamma Ray Observatory.
(BATSE stands for "Burst and Transient Source Experiment")
The BATSE Group to date has about 2000 gamma
ray bursts recorded. The following image shows the position of 2000 bursts
detected by BATSE, with no indication of strength or average energy.
Before the systematic BATSE observations,
a common hypothesis was that gamma ray bursts
occurred in the disk of our galaxy.
The above sky maps contradict this hypothesis because it indicates that the
distribution of bursts is isotropic (no preferred direction). This tells us
that either the gamma ray bursts come from events at great distances
(cosmological distances), or that they come from events in the more spherical
halo of our galaxy.
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