Looking down the barrel
Interestingly, one should expect nearby sources of gamma rays to statistically cluster towards where the bulk of the Milky Way lies; yet, on the contrary, they looked uniformly distributed in every direction without preference.
But then, if the origins were really extragalactic, given the intensity of recorded events, the underlying source had to be of unimaginably high power, something briefly outshining the whole visible Universe taken together.
At least this was the result of basic calculations taking into account the flash measured intensities and estimated dimming from average intergalactic distances. Worse yet, given their brief duration, the size of the engine should be relatively small to account for a causal connection that could not travel faster than light itself, thus ruling out anything larger than the solar system or less.
This posed an annoying problem. Was there a hitherto unknown class of phenomena capable of releasing such massive amounts of energy? Were GRB's of local nature but by some unexplained reason looked as coming from everywhere?
That the spatial resolution of available detectors were not good enough did not help, much more so when the atmosphere is opaque to gamma rays; that is, they readily strike atoms high in the stratosphere and do not reach ground detectors, leaving satellites as the only option.
The first evidences
Something astronomers were desperately seeking for decades was an optical counterpart, that is, a visible light source that could be reliably associated with a detected GRB event. This had eluded scientists for decades given the poor capability of satellites to accurately pinpoint the sky coordinates of a detected event, and the swift action that had to be taken to catch the fleeting afterglow.
This was to change with better satellites and a more responsive communications network capable of relaying breaking news in time for ground based observatories to gear up.
For the first time, on Feb 28, 1997, the now defunct and second in the series of NASA's great observatories, the Compton Gamma Ray Observatory, detected an event the Dutch-Italian BeppoSAX X-ray observatory located with sufficient accuracy and speed to allow doctoral students Paul Groot and Titus Galama using the 4 m. William Herschel telescope in Canarias to catch a 21 magnitude afterglow a few hours later.
And it was bizarre, to the delight of advocates for extragalactic GRB origins, and criticism from unconvinced opponents. The first tentative evidence pointed to a probable supernova in a billions of light years
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