GCN Circular 40914
Subject
GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
Event
Date
2025-07-03T12:51:12Z (16 hours ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
Via
email
D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
On July 2, 2025, Konus-Wind (KW) detected, in the waiting mode,
a hard X-ray activity, consistent in time with GRBs 250702B, C, D, E,
reported by Fermi-GBM team (GCN 40883, 40885, 40886, 40890, 40891),
localized by Swift/BAT-GUANO (GCN 40903),
associated with the X-ray transient EP250702a (GCN 40906),
and detected by MAXI/GSC (GCN 40910).
KW observed multiple overlapped emission episodes
in in the time interval from ~12:40 to ~16:50 UT.
The emission is clearly visible in all three KW waiting mode
energy bands (20-75, 75-300, 300-1250 keV).
From our preliminary background estimates,
the total duration of the event is >~15.5 ks.
The Konus-Wind light curve is available at
http://www.ioffe.ru/LEA/GRBs/GRB250702BCDE/
In the 20-1250 keV range, the time-integrated spectrum of the emission is best described
by a simple power law (PL) function with the PL photon index of (-1.3 ± 0.06).
The total observed fluence in this energy band is (5.95 ± 0.32)x10^-4 erg/cm^2
and the 2.944 s peak energy flux is (5.33 ± 0.29)x10^-7 erg/cm^2/s.
All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.