GCN Circular 38895
Subject
Konus-Wind detection of GRB 250107C
Date
2025-01-10T15:59:26Z (a month 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:
The long GRB 250107C (SVOM/GRM observation: Xue et al., GCN 38870;
IPN triangulation: Svinkin et al., GCN 38879)
triggered Konus-Wind (KW) at T0=67934.719 s UT (18:52:14.719).
The burst consists of two overlapping peaks and had the total duration of ~4 s.
The emission is seen up to ~10 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB250107_T67934/
As observed by Konus-Wind, the burst had
a fluence of (3.02 ± 0.13)x10^-5 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 0.960 s,
of (2.23 ± 0.15)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum (measured from T0 to T0+10.752 s)
is best fit in the 20 keV - 15 MeV range
by a GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.41 (-0.06,+0.06),
the high energy photon index beta = -3.03 (-0.28,+0.18),
the peak energy Ep = 254 (-10,+11) keV,
chi2 = 78/79 dof.
The spectrum near the peak count rate (measured from T0+0.768 s to T0+1.024 s)
is best fit in the 20 keV - 15 MeV range
by a GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.01 (-0.13,+0.15),
the high energy photon index beta = -3.09 (-0.49,+0.29),
the peak energy Ep = 286 (-22,+21) keV,
chi2 = 30/38 dof.
All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.