TITLE: GCN CIRCULAR NUMBER: 21884 SUBJECT: GRB 170906A CALET Gamma-Ray Burst Monitor detection DATE: 17/09/15 04:28:50 GMT FROM: Takanori Sakamoto at AGU A. V. Penacchioni, A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama, Y. Yamada, A. Tezuka, S. Matsukawa (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), P. S. Marrocchesi (U of Siena) and the CALET collaboration: The long-duration GRB 170906A (Siegel et al., GCN Circ. 21821; Hamburg et al., GCN Circ. 21839; Tsvetkova et al., GCN Circ. 21859) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 00:43:05.59 on 6 September 2017. The burst signal was seen by the all CGBM instruments. The light curve of the SGM shows a complex structure. The emission starts at T0 sec and the brightest pulse peaks at T+35 sec. The entire emission ends at T+100 sec. The T90 duration measured by the SGM data is 78.4 +- 1.9 sec (40-1000 keV). The light curve is available at http://cgbm.calet.jp/cgbm_trigger/flight/1188693801/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University.