TITLE: GCN CIRCULAR NUMBER: 18605 SUBJECT: GRB 151107B: CALET Gamma-Ray Burst Monitor detection DATE: 15/11/15 00:45:59 GMT FROM: Takanori Sakamoto at AGU A. Yoshida, T. Sakamoto, I. Takahashi, Y. Kawakubo, K. Senuma, M. Moriyama, Y. Yamada (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena) and the CALET collaboration: The long-duration GRB 151107B (Stanbro et al. GCN Circ. 18570) triggered the CALET Gamma-Ray Burst Monitor (CGBM) at 20:24:54.77 UT on 7 November 2015. The burst was detected by all three CGBM instruments. Based on the signal-to-noise among the instruments, the incident angle of the burst was estimated as ~40-70 deg from the zenith direction of CGBM. This estimated incident angle is roughly consistent with the IPN triangulation (Hurley et al., GCN Circ. 18577). The light curve of the Soft Gamma-ray Monitor (SGM; 30 keV - 20 MeV) shows the main peak starting from T0-5 sec, peaking at T0+5 sec and ending at T0+~30 sec. The second weak peak starts from T0+90 sec, peaks at T0+95 sec and ends at T0+100 sec. The T90 duration measured by the SGM data is 95.0 +- 1.4 s (40-920 keV). Currently, CALET is in the commissioning phase. Further information about CALET and CGBM can be found at http://calet.jp/en/ and http://www.en.yoshida-agu.net/research/calet-gbm