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

TL;DR

The INTEGRAL SPI instrument can detect and localize gamma-ray bursts within its field of view and quasi-omnidirectionally using its anticoincidence shield, providing valuable data for gamma-ray burst studies.

Contribution

This paper details SPI's gamma-ray burst detection capabilities, including localization rates and the use of the anticoincidence shield for quasi-omnidirectional detection.

Findings

SPI localizes ~0.8 GRBs per month within its FoV.

The anticoincidence shield detects ~0.8 GRB candidates daily.

About 0.3 GRBs per day are localized via interplanetary network triangulation.

Abstract

The spectrometer SPI, one of the two main instruments of the INTEGRAL spacecraft, offers significant gamma-ray burst detection capabilities. In its 35 deg (full width) field of view SPI is able to localise gamma-ray bursts at a mean rate of ~ 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.