TITLE: GCN CIRCULAR NUMBER: 44177 SUBJECT: GRB 260401A: CALET Gamma-Ray Burst Monitor detection DATE: 26/04/01 16:20:41 GMT FROM: Yuta Kawakubo at Aoyama Gakuin University <kawakubo@phys.aoyama.ac.jp> N. Cannady (GSFC), 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), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena), and the CALET collaboration: The long GRB 260401A (Fermi GBM Final Real-time Localization: Fermi GBM team, GCN Circ. 44174; BALROG localization: Preis et al., GCN Circ 44175; MAXI/GSC detection: Usuki et al., GCN Circ 44176) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 10:53:31.52 UTC on 1 April 2026 (https://cgbm.calet.jp/cgbm_trigger/flight/1459075956/index.html). The burst signal was seen by all CGBM detectors. The burst light curve shows a single pulse that starts at T+1.4 sec, peaks at T+2.2 sec, and ends at T+6.3 sec. The T90 and T50 durations measured by the SGM data are 4.4 +/- 0.6 sec and 2.0 +/- 0.3 sec (40-1000 keV), respectively. The ground-processed light curve is available at https://cgbm.calet.jp/cgbm_trigger/ground/1459075956 The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at Waseda University. View this GCN Circular online at https://gcn.nasa.gov/circulars/44177. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...