TITLE: GCN CIRCULAR NUMBER: 18475 SUBJECT: GRB 151006A: CALET Gamma-Ray Burst Monitor detection DATE: 15/10/27 00:49:24 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) and the CALET collaboration: The long-duration GRB 151006A (Kocevski et al., GCN Circ. 18398; Cummings et al., GCN Circ. 18409; Roberts & Meegan, GCN Circ. 18404; Golenetskii et al., GCN Circ. 18413; Bhalerao et al., GCN Circ. 18422) triggered the CALET Gamma-Ray Burst Monitor (CGBM) at 09:54:59.97 UT on 6 October 2015. The clear burst signal was detected by the Soft Gamma-ray Monitor (SGM; 30 keV - 20 MeV) which is a scintillation detector utilized a BGO crystal. Due to a large incident angle of the event, no signal was detected by the Hard X-ray Monitor (HXM; 7 keV - 1 MeV) which is a scintillation detector composed of a LaBr3(Ce) crystal. The SGM light curve shows two spikes peaking at T0-2s and T0+2s, and the emission ending around T0+~60s. The T90 duration measured by the SGM data is 63 +- 5 s (30 - 1000 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