GCN Circular 43405
Subject
Konus-Wind detection of GRB 251230A / EP251230a
Event
Date
2026-01-14T19:13:21Z (11 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 long-duration GRB 251230A / EP251230a
(Swift-BAT detection: Lanava et al., GCN 43252;
Einstein Probe-WXT detection: Wang et al., GCN 43259;
Wang et al., GCN 43272;
Insight-HXMT/HE detection: Guo et al., GCN 43299;
GECAM-B detection: Guo et al., GCN 43301)
triggered Konus-Wind at T0=04927.542 s UT (01:22:07.542).
The burst light curve shows a multipeaked structure
which starts at ~T0-25 s and has a total duration of ~73 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/GRB251230_T04927/
As observed by Konus-Wind, the burst
had the total fluence of 2.03(-0.15,+0.17)x10^-5 erg/cm2,
and the 64-ms peak flux, measured from T0-0.224 s,
of 2.51(-0.71,+0.80)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 = -1.04(-0.14,+0.16)
and Ep = 354(-47,+64) keV (chi2 = 93/98 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.2
(chi2 = 93/97 dof).
The spectrum near the maximum count rate
(measured from T0 to T0+0.256 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 = -0.70(-0.51,+0.72)
and Ep = 350(-85,+147) keV (chi2 = 19/15 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.8
(chi2 = 18/14 dof).
All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.