TITLE:   GCN CIRCULAR
NUMBER:  29913
SUBJECT: GRB 210424B: CALET Gamma-Ray Burst Monitor detection
DATE:    21/04/30 12:32:09 GMT
FROM:    Valentin Pal'shin at AGU  <val@phys.aoyama.ac.jp>

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),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The short GRB 210424B (IPN triangulation: Hurley, GCN Circ. 29909;
Konus-Wind detection: Svinkin et al., GCN Circ. 29911) triggered the CALET
Gamma-ray Burst Monitor (CGBM) at 08:01:55.115 UTC on 24 April 2021
(http://cgbm.calet.jp/cgbm_trigger/flight/1303286436/). The burst signal
was seen mainly by the SGM detector.
The burst light curve shows a multi-peaked structure which starts
at T+0.40 sec, peaks at 1.28 sec and ends at T+1.42 sec.
The T90 and T50 durations measured by the SGM data are 1.04 +- 0.16 sec
and 0.56 +- 0.15 sec (40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1303286436/

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