GRB 170402A

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

The long-duration GRB 170402A (Fermi GBM trigger #512808659;
Konus-Wind trigger time on 06:50:51.076) triggered the CALET
Gamma-ray Burst Monitor (CGBM) at 06:50:52.11 on 2 April 2017.
The burst signal was only seen by the SGM instrument.

The light curve of the SGM shows several peaks.  The entire
burst episode starts at T+2 sec and ends at T+12 sec.  Two bright
emissions peak at T+3 sec and T+5 sec.  The T90 duration measured
by the SGM data is 7.5 +- 0.6 sec (40-1000 keV).

The light curve is available at

http://cgbm.calet.jp/cgbm_trigger/flight/1175150695/

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

V. Sharma, V. Bhalerao (IITB) and D. Bhattacharya (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data showed clear detection of GRB 170402A (CALET Gamma-Ray Burst Monitor detection: T. Sakamoto et al., GCN Circ. 20980
Loading...
 
 ) in the 40-200 keV energy range in the quadrant C and D only. The light curve shows multiple peak emission with main peak at 06:50:57.076 UT, ~5 s after the CALET trigger. The measured peak count rate is 323.4 counts/sec above the background in combined data of four quadrants, with a total 2197 counts. The local mean background count rate was 363.6 counts/s. Using cumulative rates, we measure a T90 of 13 s.

It was clearly detected in the CsI anticoincidence detector (Veto) also as in the 100-500 keV energy range.

CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.