GCN Circular 41109
Subject
Konus-Wind detection of GRB 250716A
Event
Date
2025-07-17T15:32:45Z (3 days ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
Via
Web form
D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia,
A. Tsvetkova, M. Ulanov, and T. Cline
on behalf of the Konus-Wind team, report:
The bright, long-duration GRB 250716A
(Fermi-GBM detection: Fermi GBM team, GCN 41099;
Mukherjee and Meegan, GCN 41102)
triggered Konus-Wind at T0=5348.122 s UT (01:29:08.122).
The burst light curve shows a multipeaked structure
which starts at ~T0-91 s and has a total duration of ~235 s.
The emission is seen up to ~20 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB250716_T05348/
As observed by Konus-Wind, the burst
had a fluence of 2.39(-0.09,+0.09)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+2.544 s,
of 4.26(-0.33,+0.33)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+88.064 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.25(-0.04,+0.04),
the high energy photon index beta = -1.78(-0.04,+0.03),
the peak energy Ep = 554(-84,+93) keV
(chi2 = 124/97 dof).
The spectrum near the maximum count rate
(measured from T0+0.256 to T0+4.096 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.78(-0.06,+0.07),
the high energy photon index beta = -1.59(-0.03,+0.03),
the peak energy Ep = 726(-113,+139) keV
(chi2 = 106/86 dof).
All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.