[vsnet-grb-info 17357] GRB 151225A: CALET Gamma-Ray Burst Monitor detection of a possible short GRB

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18724
SUBJECT: GRB 151225A: CALET Gamma-Ray Burst Monitor detection of a possible short GRB
DATE:    15/12/26 02:37:37 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto at phys.aoyama.ac.jp>

Y. Kawakubo, A. Yoshida, T. Sakamoto, I. Takahashi, 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:

A possible short-duration GRB 151225A (trigger #1135105601) triggered the CALET 
Gamma-Ray Burst Monitor (CGBM) at 19:09:10.34 UT on 25 December 2015.  The clear 
burst signal was detected by all three CGBM instruments.  

The light curve of the SGM shows a double peak structure.  The initial spike 
starts and peaks around T0.  The second peak starts around T0+0.5 sec, peaks 
around T0+0.7 sec and ending around T0+1.5 sec.  Above 500 keV band, the first 
peak looks insignificant, instead the 2nd peak is clearly visible.  Based on the 
light curve inspection, the signal is clearly visible up to ~1.5 MeV.  Low energy 
data show no significant soft extended emission above ~7 keV.  The T90 duration 
measured by the SGM data is 1.87 +- 0.13 sec (40-450 keV).  

Identification of this possible short event by other spacecraft is strongly encouraged.