[vsnet-grb-info 18169] GRB 160625B CALET Gamma-Ray Burst Monitor detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19617
SUBJECT: GRB 160625B CALET Gamma-Ray Burst Monitor detection
DATE:    16/06/29 08:09:50 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto at phys.aoyama.ac.jp>

S. Nakahira (JAXA), A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama,
Y. Yamada (AGU), K. Yamaoka (Nagoya U), 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) P. S. Marrocchesi (U of Siena)
and the CALET collaboration:

The long-duration GRB 160625B (Burns et al., GCN Circ. 19581;
Dirirsa et al. GCN Circ. 19586; INTEGRAL-ACS #7495) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 22:40:15.49 on 25 June 2016.  The burst signal
was seen by all CGBM instruments.

The light curve of the SGM shows a precursor emission starting at T+0.5 sec,
peaking at T+1 sec and ending at T+2 sec.  Then, the bright main burst episode
follows starting from T+183 sec and ending at T+233 sec with overlapping
multiple pulses.  The T90 duration measured by the SGM data for the main
bright episode is 20.0 +- 0.4 sec (40-1000 keV).  The T90 duration of the precursor
emission measured by the SGM data is 0.8 +- 0.1 sec (40-1000 keV).
The light curve is available at

http://cgbm.calet.jp/cgbm_trigger/flight/1150929566/

Furthermore, the main pulse was also detected by Imaging Calorimeter (IMC;
plastic scintillating fibers) and Charge Detector (CHD; plastic scintillators),
which are subsystems of the CALET main instrument Calorimeter (CAL).  The
incident angles for this burst was 61 degrees and 67 degrees from the boresight
of CAL at the trigger time and at the main peak, respectively.
The CAL gamma-ray analysis (>1 GeV) is in progress.

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