{
  "bibcode": "2022GCN.32660....1G",
  "body": "D. Gotz (CEA Paris Saclay), S. Mereghetti (INAF/IASF Milano), V. Savchenko, C. Ferrigno, E. Bozzo (ISDC Versoix) on behalf of the IBAS team report:\n\nGRB221009A/Swift J1913.1+1946 (GCN 32635) has been detected in the SPI/ACS. \nIt presents a multi-peaked structure with a first episode (precursor) staring at 13:16:58 UTC, peaking at 13:17:01 and lasting about 17 s.  \n\nThe GRB main episode starts at t_0 = 13:19:52 UTC and includes a complex multi-peaked structure, with three main peaks lasting about 460 s.\n\nThe fluence of the main episode is about 1.3e8 counts, which, based on the average conversion factor of Vigano' & Mereghetti 2009 (https://arxiv.org/abs/0912.5329 <https://arxiv.org/abs/0912.5329>), corresponds to 0.013 erg/cmsq in the 75 keV-1 MeV energy range.  This fluence value corresponds to an E_Iso of 8e53 erg (assuming a redshift z=0.151, GCN 32648).\n\nWe note that the fluence and E_Iso values are lower limits, due to the instrument saturation at the peak of the event.\n\nThe main episode if followed by a long tail with a power law time decay with index  of about  -1.6 and extending for at least 40 minutes after the precursor.",
  "circularId": 32660,
  "createdOn": 1665413556000,
  "email": "diego.gotz@cea.fr",
  "subject": "GRB221009A/Swift J1913.1+1946: INTEGRAL SPI/ACS observations",
  "submitter": "Diego Gotz at CEA  <diego.gotz@cea.fr>",
  "eventId": "GRB 221009A"
}