TITLE: GCN CIRCULAR NUMBER: 22209 SUBJECT: GRB 171120A CALET Gamma-Ray Burst Monitor detection DATE: 17/12/08 00:27:12 GMT FROM: Takanori Sakamoto at AGU Y. Yamada, A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama, 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), A. V. Penacchioni, P. S. Marrocchesi (U of Siena) and the CALET collaboration: The long-duration GRB 171120A (Tohuvavohu et al., GCN circ. 22133; Longo et al., GCN circ. 22136; Frederiks et al., GCN circ. 22142; Sharma et al., GCN circ. 22143; Li et al., GCN circ. 22149) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 13:20:02 on 20 November 2017. The burst signal was seen by the all CGBM instruments. The light curve of the SGM shows two largely separated episodes. The first episode starts at T0, peaks at T+1 sec and ends at T+4 sec. The second episode starts T+38 sec, peaks at T+40 sec and ends at T+46 sec. The T90 duration measured by the SGM data is 44.4 +- 0.9 sec (40-1000 keV). The light curve is available at http://cgbm.calet.jp/cgbm_trigger/flight/1195219087/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University.