The gamma-ray burst detector system on board Ginga.

The system design and in-flight performance of the Gamma-ray Burst Detector (GBD) on board the Japanese X-ray astronomy satellite Ginga are presented. The GBD subsystem started observations on February 26, and it has since then continuously monitored the occurrence of cosmic gamma-ray bursts. It had detected at least 24 gamma-ray burst candidates by the end of March 1988. The number of observed bursts is consistent with the preflight estimation, indicating that the instrument is performing as designed. This paper describes details of the instrument and the in-orbit performance of the detector system, including considerations of background rates and gain stabilities. One example of an observed cosmic gamma-ray burst is also presented.