TITLE:   GCN CIRCULAR
NUMBER:  22738
SUBJECT: GRB 180523A: CALET Gamma-Ray Burst Monitor detection
DATE:    18/05/25 03:50:00 GMT
FROM:    Valentin Pal'shin at AGU  <val.palshin@gmail.com>

A. Tezuka, A. Yoshida, T. Sakamoto, V. Pal'shin, Y. Kawakubo,
S. Matsukawa, H. Onozawa (AGU), K. Yamaoka (Nagoya U),
S. Nakahira (RIKEN), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa,
S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U),
W. Ishizaki (ICRR), M. L. Cherry (LSU), S. Ricciarini (U of Florence),
A. V. Penacchioni, P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The long-duration, bright GRB 180523A (INTEGRAL SPI-ACS trigger #8063)
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 18:20:26.844 UTC
on 23 May 2018. The burst signal was seen by all CGBM detectors.

The burst light curve shows a bright, multi-peaked pulse which
starts at T+1.3 sec, peaks at T+18.5 sec and ends at ~T+37.3 sec,
followed by a very weak pulse seen from ~T+88 sec to ~T+109 sec.
The T90 and the T50 durations measured by the SGM data are
50.0 +- 35.6 sec and 9.9 +- 0.8 sec (40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1211134810/

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