GCN Circular 44371
Subject
GRB 260415B: CALET Gamma-Ray Burst Monitor detection
Event
Date
2026-04-21T09:51:16Z (3 days ago)
From
Yuta Kawakubo at Aoyama Gakuin University <kawakubo@phys.aoyama.ac.jp>
Via
Web form
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 260415B
(Fermi GBM Final Real-time Localization: Fermi GBM team, GCN #44300;
NuSTAR detection: Waratkar et al., GCN #44302; Glowbug gamma-ray
detection: Woolf et al., GCN #44313) at 02:28:55.55 UTC on 15 April 2026
(https://cgbm.calet.jp/cgbm_trigger/flight/1460255329/index.html).
The burst signal was seen by all CGBM detectors.
The burst light curve shows a multi-peaked structure starting
at T-2.9 s, peaking at T+22.1 s, and ending at T+124.5 s.
The T90 and T50 durations measured with the SGM data are 111.6 +/- 1.8 s
and 50.7 +/- 1.0 s (40-1000 keV), respectively.
The ground-processed light curve is available at
https://cgbm.calet.jp/cgbm_trigger/ground/1460255329/
The CALET data used in this analysis were provided by
the Waseda CALET Operation Center located at Waseda University.