TITLE:   GCN CIRCULAR
NUMBER:  19424
SUBJECT: GRB 160509A: CALET Gamma-Ray Burst Monitor detection
DATE:    16/05/12 06:41:12 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

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), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena) 
and the CALET collaboration:

The long-duration GRB 160509A (Longo et al., GCN circ. 19403; Ono et al., 
GCN circ. 19404; Roberts et al., GCN circ. 19411; Frederiks et al., GCN circ. 19417) 
triggered the CALET Gamma-Ray Burst Monitor (CGBM) at 08:58:51.21 on 9 May 2016.  
The burst signal was seen by all CGBM instruments.  The angular separations between 
the GRB position (Kennea et al., GCN 19408) and the boresignt of the HXM and 
the SGM instrument at the trigger time were 108 deg. and 104 deg., respectively.  
Therefore, the GRB was outside the field of view of the CAL instrument.

The light curve of the SGM shows multiple overlapping pulses with a broad structure 
starting from T0-5 sec, peaking at T0+9 sec and ending at T0+30 sec.  A hint of the 
emission is seen at T0+~370 sec.  The T90 duration measured by the SGM data is 
14.6 +- 0.6 sec (40-1000 keV).

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