GCN Circular 44923

S. Nakahira (JAXA), A. Yoshida, T. Sakamoto, S. Sugita, 
Y. Kawakubo (AGU), K. Yamaoka (Nagoya U), 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),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The CALET Gamma-ray Burst Monitor (CGBM) detected GRB 260611B
at 21:32:32.02 UTC on 11 June 2026 (trigger #1465248636;
https://cgbm.calet.jp/cgbm_trigger/flight/1465248636/index.html).
A CGBM Notice was distributed in near real time.

This event was also reported by Fermi GBM (Fermi GBM Team., GCN #44917
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 ).

The burst signal was seen by all CGBM detectors.
The burst light curve shows a multi-peaked structure starting
at T+0.2 s, peaking at T+14.7 s, and ending at T+28.4 s.
The T90 and T50 durations measured with the SGM data are 24.7 +/- 0.9 s
and 13.5 +/- 1.2 s in the 40-1000 keV band, respectively.


The ground-processed light curve is available at:
https://cgbm.calet.jp/cgbm_trigger/ground/1465248636/

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