[vsnet-grb-info 20545] GRB 180411B: CALET Gamma-Ray Burst Monitor detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22641
SUBJECT: GRB 180411B: CALET Gamma-Ray Burst Monitor detection
DATE:    18/04/12 12:22:46 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto at phys.aoyama.ac.jp>

T. Sakamoto, A. Yoshida, V. Pal'shin, Y. Kawakubo, A. Tezuka, 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, soft-spectrum, bright GRB 180411B (Konus-Wind trigger time on 08:38:56.08)
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 08:37:29.769 UTC on 11 April 2018.
The burst signal was seen by all CGBM detectors.

The burst light curve shows several multi-peaked pulses which start at T0, peak at T+82 sec
and end at T+123 sec.  The T90 and the T50 durations measured by the SGM data are
99.0 +- 1.8 sec and 43.8 +- 1.7 sec (40-1000 keV), respectively.  Despite its brightness,
the burst signal is seen only below ~300 keV indicating the soft spectrum.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1207471016/

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