GCN Circular 38954
Subject
Konus-Wind detection of GRB 250113A
Date
2025-01-15T13:54:39Z (7 days ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
Via
Web form
A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The long-duration GRB 250113A
(SVOM/GRM observation: Wang et al., GCN 38923;
INTEGRAL/SPI-ACS detection: Barria et al., GCN 38935;
IPN triangulation: Kozyrev et al., GCN 38953)
triggered Konus-Wind at T0=23073.686 s UT (06:24:33.686).
The burst light curve shows a multipeaked structure
which starts at ~T0-3.0 s and has a total duration of ~46.8 s.
The emission is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB250113_T23073/
As observed by Konus-Wind, the burst
had a fluence of 3.88(-0.13,+0.14)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+0.656 s,
of 6.12(-1.01,+1.03)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+49.408 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -1.42(-0.05,+0.05)
and Ep = 251(-18,+21) keV (chi2 = 75/88 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.5
(chi2 = 75/87 dof).
The spectrum near the maximum count rate
(measured from T0+0.256 to T0+8.448 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 = -0.19(-0.16,+0.19),
the high energy photon index beta = -2.49(-0.27,+0.18),
the peak energy Ep = 321(-30,+31) keV
(chi2 = 59/74 dof).
All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.