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GCN Circular 29553

Subject
GRB 210222A: CALET Gamma-Ray Burst Monitor detection
Date
2021-02-23T10:08:53Z (3 years ago)
From
Valentin Pal'shin at AGU <val@phys.aoyama.ac.jp>
P. S. Marrocchesi (U of Siena),
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), N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
and the CALET collaboration:

At 15:57:23.469 UTC on 22 February 2021, the CALET Gamma-ray Burst
Monitor (CGBM) triggered on long GRB 210222A
(http://cgbm.calet.jp/cgbm_trigger/flight/1298044600/),
which was also detected by the MAXI/GSC at T0(CGBM)+116 s
(Nakajima et al., GCN Circ. 29543).
The burst signal was seen by all CGBM detectors.

The burst light curve shows a FRED-like pulse which starts at T+0.6 sec,
peaks at T+7.5 sec, and ends at T+87.3 sec. The T90 and T50 durations
measured by the SGM data are 71.4 +- 11.5 sec and 33.5 +- 4.4 sec
(40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1298044600/

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