GRB 030131: a long Gamma-Ray Burst detected with INTEGRAL during a satellite slew

A long Gamma-Ray Burst (GRB) was detected with the instruments on board the INTEGRAL satellite on January 31 2003. Although most of the GRB, which lasted 150 seconds, occurred during a satellite slew, the automatic software of the INTEGRAL Burst Alert System was able to detect it in near-real time. Here we report the results obtained with the IBIS instrument, which detected GRB 030131 in the 15 keV - 200 keV energy range, The burst displays a complex time profile with numerous peaks. The peak spectrum can be described by a single power law with photon index Γ1.7 and has a flux of 2 photons cm−2 s−1 in the 20-200 keV energy band. The high sensitivity of IBIS has made it possible for the first time to perform detailed time-resolved spectroscopy of a GRB with a fluence of 7×10−6 erg cm−2 (20-200 keV)