The optical counterparts of γ-ray bursts

The origin of γ-ray bursts-which are among the most energetic events in the Universe-has puzzled astronomers for 25 years. Since 1991, new events have been discovered at a rate of about one per day, but because their positions were poorly determined, the objects responsible for these outbursts could not be identified. Now, following the launch of the BeppoSAX satellite in 1996, γ-ray bursts have been rapidly and accurately located, which has led to the breakthrough discoveries of X-ray and optical counterparts in 1997, and the demonstration that these objects are in general very distant.