It had been produced by a cosmic cataclysm near the edge of the Universe and had been travelling through space for billions of years. Some of gamma rays were picked up by two orbiting satellites with instruments set to detect them. Signals from the satellites triggered an automatic Internet alert. Within 22 seconds, an optical telescope in New Mexico swung towards the position in the sky from which the burst had come. The analysis of the data collected has now been published in a group of papers published in the leading journals Nature and Science.
Astronomers detect gamma-ray bursters almost every day.
They believe these flashes of intense radiation are caused when two, super-dense stars, called neutron stars, collide. Neutron stars are small, only about 25 km across, but a teaspoonful of neutron star material would weigh a billion tonnes. Some speculate that a gamma burst signifies the violent birth of a black hole. When the neutron stars collide there is a titanic explosion - one that literally ripples to the other end of the Universe. This burst was named GRB 990123.