GCN Circular 44989
Subject
GRB 260617A: CALET Gamma-Ray Burst Monitor detection
Event
Date
2026-06-19T08:20:00Z (4 months ago)
From
Yuta Kawakubo at Aoyama Gakuin University <kawakubo@phys.aoyama.ac.jp>
Via
Web form
S. Torii (Waseda U), A. Yoshida, T. Sakamoto, S. Sugita, Y. Kawakubo (AGU),
K. Yamaoka (Nagoya U), S. Nakahira (JAXA), Y. Asaoka (ICRR), 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 260617A
at 21:36:43.92 UTC on 17 June 2026 (trigger #1465767277;
https://cgbm.calet.jp/cgbm_trigger/flight/1465767277/index.html).
No real-time CGBM GCN Notice was distributed about this trigger because
the real-time communication from the ISS was off (loss of signal).
This event was also reported by Fermi GBM (The Fermi GBM team et al., GCN #44969;
Godwin et al., GCN #44972), Konus-Wind and Mars-Odyssey (IPN triangulation: Kozyrev et al., GCN #44982).
The burst signal was seen by HXM1 and SGM. The burst light curve shows a short pulse from T-0.25 s to T-0.15 s.
The T90 and T50 durations measured with the SGM data are 0.09 +/- 0.02 s
and 0.05 +/- 0.01 s in the 40-1000 keV band, respectively.
The ground-processed light curve is available at:
https://cgbm.calet.jp/cgbm_trigger/ground/1465767277/
The CALET data used in this analysis were provided by
the Waseda CALET Operation Center located at Waseda University.