TITLE:   GCN CIRCULAR
NUMBER:  32974
SUBJECT: GRB 221121A: CALET Gamma-Ray Burst Monitor detection
DATE:    22/11/23 07:05:35 GMT
FROM:    Yuta Kawakubo at Louisiana State U./CALET  <kawakubo1@lsu.edu>

T. Sakamoto, A. Yoshida,  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),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long GRB 221121A (Fermi GBM Final Real-time Localization:
Fermi GBM team, GCN Circ. 32960; AstroSat CZTI detection:
Gopalakrishnan et al., GCN Circ 32969; IPN triangulation: 
Kozyrev etc al., GCN Circ. 32971) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 06:34:47.10 UTC on 21 November 2022
(http://cgbm.calet.jp/cgbm_trigger/flight/1353047657/index.html).
The burst signal was seen by only SGM detector.

The burst light curve shows a single pulse which starts
at T+2.6 sec, peaks at T+3.1 sec, and ends at T+30.2 sec.
The T90 and T50 durations measured by the SGM data are 24.1 +/- 0.8 sec
and 10.1 +/- 1.7 sec (40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1353047657/

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