TITLE: GCN CIRCULAR NUMBER: 43860 SUBJECT: GRB 260226A: CALET Gamma-Ray Burst Monitor detection DATE: 26/02/27 08:55:16 GMT FROM: Yuta Kawakubo at Aoyama Gakuin University <kawakubo@phys.aoyama.ac.jp> K. Kobayashi (Waseda U), A. Yoshida, T. Sakamoto, S. Sugita, Y. Kawakubo (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), Y. Asaoka (ICRR), S. Torii, Y. Akaike, Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena), and the CALET collaboration: The long GRB 260226A (Fermi GBM Final Real-time Localization: Fermi GBM team, GCN Circ. 43840; BALROG localization: Preis et al., GCN Circ 43843; Fermi-LAT detection: Depalo et al., GCN Circ 43844; AstroSat CZTI detection: Harsha et al., GCN Circ 43846; Fermi-LAT refined analysis: Depalo et al., GCN Circ 43850; Fermi GBM observation: Bissaldi et al., GCN Circ 43851; NuSTAR detection: Waratkar et al., GCN Circ 43854; Glowbug gamma-ray detection: Woolf et al., GCN Circ 43855) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 10:38:04.46 UTC on 26 February 2026 (https://cgbm.calet.jp/cgbm_trigger/flight/1456137494/index.html). The burst signal was seen by all CGBM detectors. The burst light curve shows a multi-peaked structure that starts at T-3.9 sec, peaks at T+11.1 sec, and ends at T+37.0 sec. The T90 and T50 durations measured by the SGM data are 16.0 +/- 0.3 sec and 8.2 +/- 0.1 sec (40-1000 keV), respectively. The ground-processed light curve is available at https://cgbm.calet.jp/cgbm_trigger/ground/1456137494/ 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/43860. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...