1INTEGRAL JOINS THE 3RD INTERPLANETARY NETWORK

The BGO anticoincidence shield of the SPI detec-tors has a maximum effective area of over 5000 cm2, and operates in the energy range>75 keV. It was in-corporated into the 6- spacecraft interplanetary net-work shortly after launch. It detects about one con-firmed burst every three days, and has detected over 125 cosmic and soft gamma repeater bursts since it started operation. It also detects numerous other bursts which are below the thresholds of the other IPN instruments and are therefore unconfirmed, but which are almost certainly cosmic. We describe the operation of the SPI-ACS and some of its unique fea-tures, and explain how the data on bursts are being utilized by the scientific community. Key words: gamma rays; gamma-ray bursts; soft gamma repeaters. 1