GCN Circular 31332
Subject
GRB 211225B: CALET Gamma-Ray Burst Monitor detection
Date
2021-12-29T07:10:45Z (3 years ago)
From
Valentin Pal'shin at AGU <val@phys.aoyama.ac.jp>
N. Cannady (GSFC/UMBC),
A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), M. L. Cherry (LSU),
S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena),
and the CALET collaboration:
The long GRB 211225B (Swift detection and refined analysis: Page et al.,
GCN Circ. 31305, Laha et al., GCN Circ. 31312;
https://gcn.gsfc.nasa.gov/other/211225B.gcn3) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 13:13:05.685 UTC on 25 December 2021 while exiting
the radiation belts. The burst signal was seen by all CGBM detectors.
Because of a problem in one of the ground alert processing script, the GCN
notice was not distributed automatically for this event.
The burst light curve shows a single pulse which starts at T-2.2 sec,
peaks at T+3.6 sec and ends at T+42.0 sec. The extended tail is seen in
the low energy channels as long as a hint of the preceding emission (which
is clearly seen in the Swift-BAT light curve: Laha et al. GCN Circ. 31312).
The T90 and T50 durations measured by the SGM data are 32.7 +- 8.1 sec and
14.6 +- 1.9 sec (40-1000 keV), respectively.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1324473176/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.