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TITLE:   GCN CIRCULAR
NUMBER:  23779
SUBJECT: GRB 190121A: CALET Gamma-Ray Burst Monitor detection of a short burst
DATE:    19/01/24 12:08:28 GMT
FROM:    Valentin Pal'shin at AGU  <val@phys.aoyama.ac.jp>

S. Matsukawa, A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU),
Y. Kawakubo (LSU), A. Tezuka, H. Onozawa, T. Ito, H. Morita, Y. Sone (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:

At 12:55:17.284 UTC on 21 January 2019, the CALET Gamma-ray Burst 
Monitor (CGBM)
triggered on GRB 190121A.
The burst signal was detected only by the SGM detector.
Because of a problem in one of the ground alert processing scripts,
the GCN notice was not distributed automatically for this event.

This GRB is also clearly seen by the publicly available
INTEGRAL SPI-ACS light curve.

The burst light curve shows a short pulse which
starts at T-0.224 sec and ends at T+0.096 sec.
The T90 and the T50 durations measured by the SGM data are
0.288 s +- 0.091 sec and 0.128 +- 0.101 sec (40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1232110402/

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