CALET Gamma-Ray Burst Monitor detection of GRB 220308A and its possible precursor
Abstract
At 05:35:27.809 UTC on 8 March 2022, the CALET Gamma-ray Burst Monitor (CGBM) triggered on a long weak GRB followed in ~460 s by the bright GRB 220308A, localized by the IPN (Svinkin et al., GCN 31715; https://gcn.gsfc.nasa.gov/other/220308A.gcn3). Both bursts were seen by all CGBM detectors. The first (trigger) burst might be a precursor of GRB 220308A. The trigger burst light curve shows a double-peaked pulse which starts at T+1.9 sec, peaks at T+3.6 sec,and ends at T+15.0 sec. The T90 and T50 durations measured by the SGM data are 11.6 +- 1.6 sec and 7.4 +- 1.6 sec (40-1000 keV), respectively. The GRB 220308A light curve shows a multi-peaked structure which starts at T+461.6 sec, peaks at T+465.9 sec, and ends at T+481.9 sec. The T90 and T50 durations measured by the SGM data are 15.4 +- 0.4 sec and 4.0 +- 0.1 sec (40-1000 keV), respectively. The ground processed light curve is available at http://cgbm.calet.jp/cgbm_trigger/ground/1330752907/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University.
- Publication:
-
GRB Coordinates Network
- Pub Date:
- March 2022
- Bibcode:
- 2022GCN.31719....1M