TITLE: GCN CIRCULAR NUMBER: 20980 SUBJECT: GRB 170402A CALET Gamma-Ray Burst Monitor detection DATE: 17/04/04 23:31:32 GMT FROM: Takanori Sakamoto at AGU 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.