TITLE: GCN CIRCULAR NUMBER: 46095 SUBJECT: GRB 261029A: CALET Gamma-Ray Burst Monitor detection DATE: 26/10/29 16:07:41 GMT FROM: Yuta Kawakubo at Aoyama Gakuin University P. S. Marrocchesi (U of Siena), A. Yoshida, T. Sakamoto, S. Sugita, Y. Kawakubo (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC), M. L. Cherry (LSU), S. Ricciarini (U of Florence), and the CALET collaboration: The CALET Gamma-ray Burst Monitor (CGBM) detected GRB 261029A at 01:27:33.19 UTC on 29 October 2026 (trigger #1477272361; https://cgbm.calet.jp/cgbm_trigger/flight/1477272361/index.html). A CGBM Notice was distributed in near real time. This event was also reported by Fermi GBM (Fermi GBM team, GCN #46071), SVOM (Goto et al., GCN #46072), Fermi-LAT (Longo et al., GCN #46085), AstroSat CZTI (Salunke et al., GCN #46089). The burst signal was seen by all CGBM detectors. The burst light curve shows a multi-peaked structure starting at T-28.9 s, peaking at T+10.1 s, and ending at T+ 11.9 s. The T90 and T50 durations measured with the SGM data are 32.2 +/- 1.0 s and 17.6 +/- 0.3 s in the 40-1000 keV band, respectively. The ground-processed light curve is available at: https://cgbm.calet.jp/cgbm_trigger/ground/1477272361/ The CALET data used in this analysis were provided by the Waseda CALET Operation Center located at Waseda University.