TITLE: GCN CIRCULAR NUMBER: 42079 SUBJECT: GRB 251001C: CALET Gamma-Ray Burst Monitor detection DATE: 25/10/03 08:15:26 GMT FROM: Yuta Kawakubo at Aoyama Gakuin University kawakubo@phys.aoyama.ac.jp

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/UMBC), M. L. Cherry (LSU), S. Ricciarini (U of Florence), and the CALET collaboration:

The GRB 251001C (Glowbug gamma-ray detection: Cheung et al., GCN Circ. 42049) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 15:07:25.84 UTC on 1 October 2025 (https://cgbm.calet.jp/cgbm_trigger/flight/1443366004/index.html). The burst signal was seen by only the SGM detector.

The burst light curve shows a single pulse that starts at T+0.2 sec, peaks at T+1.0 sec, and ends at T+2.4 sec. The T90 and T50 durations measured by the SGM data are 2.0 +/- 0.1 sec and 0.7 +/- 0.2 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

https://cgbm.calet.jp/cgbm_trigger/ground/1443366004/

The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at Waseda University.

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