TITLE:   GCN CIRCULAR
NUMBER:  44616
SUBJECT: GRB 260510C: CALET Gamma-Ray Burst Monitor detection
DATE:    26/05/15 07:23:20 GMT
FROM:    Yuta Kawakubo at Aoyama Gakuin University <kawakubo@phys.aoyama.ac.jp>

T. Sakamoto, A. Yoshida, 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),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The CALET Gamma-ray Burst Monitor (CGBM) detected GRB 260510C 
(Fermi GBM Final Real-time Localization: Fermi GBM team, GCN #44520; 
SVOM detection of a burst: Gotz et al., GCN #44521; MAXI/GSC detection:
Iwakiri et al., GCN #44526; AstroSat CZTI detection: Arya et al., GCN #44544;
Fermi GBM Observation: Palafox et al., GCN #44564) at 17:15:37.60 UTC on 10 May 2026
(https://cgbm.calet.jp/cgbm_trigger/flight/1462468483/index.html).

The burst signal was seen by all CGBM detectors. The onboard CGBM trigger
corresponds to the second peak of the double-peaked structure reported by
Fermi/GBM and SVOM/ECLAIRs. In the CGBM ground analysis, the first peak was also
marginally visible in the SGM data. The second peak started at T+0.3 s,
peaked at T+2.9 s, and ended at T+8.9 s. The T90 and T50 durations of the
second peak, measured with the SGM data, are 7.4 +/- 0.8 s and 3.2 +/- 0.8 s
in the 40-1000 keV band, respectively.

The ground-processed light curve is available at

https://cgbm.calet.jp/cgbm_trigger/ground/1462468483/

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