INTEGRAL Spectrometer SPI's GRB detection capabilities - GRBs detected inside SPI's FoV and with the anticoincidence system ACS

The spectrometer SPI, one of the two main instruments of the INTEGRAL spacecraft, offers significant gamma-ray burst detection capabilities. In its 35degrees (full width) field of view SPI is able to localise gamma-ray bursts at a mean rate of similar to 0.8 /month. With its large anticoincidence shield of 512 kg of BGO crystals SPI is able to detect gamma-ray bursts quasi omni-directionally with a very high sensitivity. Burst alerts of the anticoincidence shield are distributed by the INTEGRAL Burst Alert System. In the first 8 months of the mission about 0.8 / day gamma-ray burst candidates and 0.3 / day gamma-ray burst positions were obtained with the anticoincidence shield by interplanetary network triangulations with other spacecrafts.