Classification of gamma-ray bursts observed by INTEGRAL

Long gamma‐ray bursts (GRBs) can be divided into three classes (‘classical’ GRBs, X-ray rich bursts and X-ray flashes), based on the ratio of their fluences in a soft energy band to a hard energy band. However, the other characteristics of the X-ray rich bursts and X-ray flashes resemble those of the classical GRBs, suggesting that they are closely related phenomena. We present the classification of more than 70 GRBs triggered by the IBAS aler t on IBIS/ISGRI since the launch of INTEGRAL’s. An optimised criterion for the classification has been ca rried out, based on the 20-50 keV and 50-200 keV energy bands. A comparison between the distributions of each burst type found in the INTEGRALsample, and those identified by Swift and HETE-2, is also presented.