GCN Circular 18706

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

The long-duration GRB 151212B (Fermi-GBM trigger #471576728) triggered the CALET 
Gamma-Ray Burst Monitor (CGBM) at 01:32:04.68 UT on 12 December 2015.  The clear 
burst signal was detected by the Soft Gamma-ray Monitor (SGM; 30 keV - 20 MeV) which 
is a scintillation detector utilized a BGO crystal.  Due to a large incident angle 
of the event, no signal was detected by the Hard X-ray Monitor (HXM; 7 keV - 1 MeV) 
which is a scintillation detector composed of a LaBr3(Ce) crystal.

The light curve of the SGM shows the main peak starting from T0, peaking 
at T0+1 sec and ending at T0+4 sec.   The T90 duration measured by the SGM 
data is 3.5 +- 0.5  sec (40-460 keV).  

Currently, CALET is in the commissioning phase.  Further information about CALET and 
CGBM can be found at http://calet.jp/en/ and http://www.en.yoshida-agu.net/research/calet-gbm