TITLE: GCN CIRCULAR NUMBER: 21259 SUBJECT: GRB 170607A CALET Gamma-Ray Burst Monitor detection DATE: 17/06/20 00:40:51 GMT FROM: Takanori Sakamoto at AGU S. Nakahira (RIKEN), A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama, Y. Yamada, A. Tezuka, S. Matsukawa (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), A. V. Penacchioni, P. S. Marrocchesi (U of Siena) and the CALET collaboration: The long-duration GRB 170607A (D'Ai et al., GCN Circ. 21214; Hamburg et al., GCN Circ. 21218; INTEGRAL SPI-ACS trigger #7864) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 23:17:56.98 on 7 June 2017. The burst signal was seen only by the SGM instrument. The light curve of the SGM shows two distinct peaks. The first peak starts at T+2 sec, peaks at T+4 sec and ends at T+8 sec. The second peak starts at T+210 sec, peaks at T+215 sec and ends at T+230 sec. The T90 durations of the first peak and the second peak measured by the SGM data separately are 4.0 +- 0.5 sec and 10.5 +- 0.8 sec (40-1000 keV). The light curve is available at http://cgbm.calet.jp/cgbm_trigger/flight/1180912206/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University.