GCN Circular 41025
Subject
GRB 250704B: CALET Gamma-Ray Burst Monitor detection
Event
Date
2025-07-08T13:15:29Z (4 days ago)
From
Yuta Kawakubo at Aoyama Gakuin University <kawakubo@phys.aoyama.ac.jp>
Via
Web form
Y. Shimizu (Kanagawa U), 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), T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena),
and the CALET collaboration:
The short GRB 250704B (SVOM/GRM observation: Wang et al., GCN 40940;
Konus-Wind detection: Frederiks et al., GCN 40972; Insight-HXMT detection:
Wang et al., GCN 40978) associated with the EP X-ray transient EP250704a
(Einstein Probe detection: Li et al., GCN 40941; refined analysis of the EP-WXT
and FXT follow-up observations: Li et al., GCN 40956) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 08:16:26.88 UTC on 4 July 2025 and the GCN/CALET Notice
was distributed near real-time
(https://cgbm.calet.jp/cgbm_trigger/flight/1435651911/index.html).
The burst signal was seen by only the SGM detector.
The burst light curve shows a double-peaked structure that starts
at T+0.21 sec, peaks at T+0.37 sec, and ends at T+0.51 sec.
The T90 and T50 durations measured by the SGM data are 0.28 +/- 0.03 sec
and 0.23 +/- 0.04 sec (40-1000 keV), respectively.
The ground-processed light curve is available at
https://cgbm.calet.jp/cgbm_trigger/ground/1435651911/
The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at Waseda University.