Working in the Netherlands, Vreeswijk and his colleagues Titus Galama and Evert Rol noticed that one of the dim star-like objects in the region was not seen in much old achival images of this sky region an announcement of the probable optical counterpart was issued immediately to colleagues around the world. Since then, many teams around the world have interrupted their usual observing programs to collect data on this rare and transient event. Far and Few Gamma ray bursts are common - observing them optically so that their distances can be measured is not. In the 27 months since the detection of the first optical counterpart, only 11 more have been found. The extreme distance and extreme brightness of these mysterious explosions is telling us something we don't understand yet.
Every clue is vital, and early measurements crucial.
Thousands have been detected since they were discovered in the late 1960s. Three months later, another optical afterglow was detected - this time in a faint galaxy whose distance could be measured. A year ago an article in Nature announced the detection of the optical detection of a gamma ray burst in a galaxy more than 12 billion light years away.