TITLE:   GCN CIRCULAR
NUMBER:  29268
SUBJECT: GRB 210104A: CALET Gamma-Ray Burst Monitor detection
DATE:    21/01/06 10:15:24 GMT
FROM:    Valentin Pal'shin at AGU  <val@phys.aoyama.ac.jp>

M. L. Cherry (LSU),
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),
S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long bright GRB 210104A (Swift detection: Troja et al.,
GCN Circ. 29233, Palmer et al., GCN Circ. 29251;
Fermi GBM detection: Malacaria et al., GCN Circ. 29246;
Konus-Wind detection: Frederiks et al., GCN Circ. 29258;
https://gcn.gsfc.nasa.gov/other/210104A.gcn3) triggered the CALET
Gamma-ray Burst Monitor (CGBM) at 11:26:56.318 UTC on 4 January 2021
(http://cgbm.calet.jp/cgbm_trigger/flight/1293794541/).
The burst signal was seen by all CGBM detectors.

The burst light curve shows multiple partially overlapped pulses which
start at T+2.5 sec and end at T+36.5 sec. The T90 and T50 durations
measured by the SGM data are 31.2 +- 2.0 sec and 11.6 +- 9.4 sec
(40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1293794541/

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