for their leadership of space missions that enabled the demonstration of the cosmological origin of gamma ray bursts, the brightest sources known in the universe.
Gamma ray bursts (GRBs) were first detected serendipitously in 1967 by gamma ray detectors aboard the Vela satellites, and were announced by Klebesadel et al. in 1973. Work by Enrico Costa and Gerald J Fishman in the last two decades have demonstrated that GRBs are of cosmological origin, and are the brightest sources known in the universe.
GRBs are intense flashes of gamma rays emanating from cosmic sources lasting for a few seconds to minutes. During the flash, a GRB outshines any stars and any galaxies in the universe. We now know that the sources of GRBs reside in distant galaxies and that they appear so bright because they emit narrow beams of relativistic particles, and those that are observed happen to have these beams directed toward Earth. We also know that there are at least two distinct types of GRBs. The long-duration bursts are associated with rare types of supernova explosions and may be caused by the formation of a black hole at the centre of a collapsing massive star. The short-duration bursts may be caused by the merger of two neutron stars.
Gamma ray bursts (GRBs) are intense flashes of gamma rays emanating from cosmic sources and lasting for a few seconds to minutes and were first detected serendipitously in 1967 by gamma ray detectors aboard the Vela satellites, and were announced by Klebesadel et al in 1973 the discovery of GRBs.
To understand the nature of GRBs the first and key step is to determine the distance of GRBs from the Earth. The two experiments, namely Burst and Transient Source Explorer (BATSE) on Compton Gamma Ray Observatory (CGRO) and BeppoSAX， play a leading role in answering this key question.
