TITLE:   GCN CIRCULAR
NUMBER:  20749
SUBJECT: GRB 170222A: CALET Gamma-Ray Burst Monitor detection
DATE:    17/02/26 10:06:52 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

S. Ricciarini (U of Florence), A. Yoshida, T. Sakamoto, Y. Kawakubo,
M. Moriyama, Y. Yamada (AGU), K. Yamaoka (Nagoya U),
S. Nakahira (JAXA), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa,
S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR),
M. L. Cherry (LSU), P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The short-duration GRB 170222A (Hamburg et al., GCN Circ. 20728;
Kozlova et al., GCN Circ. 20731; INTEGRAL-SPI/ACS trigger #7705)
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 05:00:58.48
on 22 February 2017.  The burst signal was only seen by the SGM
instruments.

The light curve of the SGM shows several peaks.  The entire burst
episode starts at T0+0.5 sec, peaks at T0+0.8 sec and ends at T0+2 sec.
The T90 duration measured by the SGM data is 1.2 +- 0.1 sec (40-1000 keV).

The light curve is available at

http://cgbm.calet.jp/cgbm_trigger/flight/1171774567/

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