[vsnet-grb-info 24517] GRB 191221B: CALET Gamma-Ray Burst Monitor detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  26616
SUBJECT: GRB 191221B: CALET Gamma-Ray Burst Monitor detection
DATE:    19/12/31 02:44:42 GMT
FROM:    Valentin Pal'shin at AGU  <val at phys.aoyama.ac.jp>

S. Sugita, A. Yoshida, T. Sakamoto, V. Pal'shin (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
Y. Asaoka, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U),
N. Cannady (GSFC/UMBC), M. L. Cherry (LSU),
S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long GRB 191221B (Swift detection: Barthelmy et al., GCN Circ. 26534,
Sakamoto et al., GCN Circ. 26562; AGILE/MCAL observations: Longo et al.,
GCN Circ. 26549; AstroSat CZTI detection: Gaikwad et al., GCN Circ. 26567;
Insight-HXMT/HE detection: Xue et al., GCN Circ. 26573;
Konus-Wind observation: Frederiks et al., GCN Circ. 26576;
https://gcn.gsfc.nasa.gov/other/191221B.gcn3) triggered the CALET
Gamma-ray Burst Monitor (CGBM) at 20:39:04.868 UTC on 21 December 2019.
The burst signal was seen by all CGBM detectors.

The burst light curve shows a multi-peaked pulse which starts
at T+1.8 sec, peaks at T+11.3 sec and ends at T+23.4 sec.
The T90 and T50 durations measured by the SGM data are
13.0 +- 1.6 sec and 4.4 +- 0.4 sec (40-1000 keV), respectively.

The ground processed light curve will be available at

http://cgbm.calet.jp/cgbm_trigger/ground/1260995788/

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.