TITLE: GCN CIRCULAR NUMBER: 21105 SUBJECT: GRB 170510A CALET Gamma-Ray Burst Monitor detection DATE: 17/05/19 02:55:29 GMT FROM: Takanori Sakamoto at AGU A. Tezuka, A. Yoshida, T. Sakamoto, Y. Kawakubo, M. Moriyama, Y. Yamada, 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 170510A (Roberts et al., GCN Circ. 21085; Bissaldi et al., GCN Circ. 21080; Svinkin et al. GCN Circ. 21090; Sharma et al. GCN Circ. 21093; INTEGRAL SPI-ACS trigger #7841) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 05:12:23.19 on 10 May 2017. The burst signal was seen by all CGBM instruments. The light curve of the SGM shows multiple peaks. The emission starts from T+5 sec, peaks at T+25 sec and ends at T+35 sec. The T90 duration measured by the SGM data is 24.9 +- 1.0 sec (40-1000 keV). The light curve is available at http://cgbm.calet.jp/cgbm_trigger/flight/1178427921/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University.