GCN Circular 44416
Subject
Konus-Wind detection of GRB 260424B
Event
Date
2026-04-28T15:28:08Z (11 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 short-duration GRB 260424B
(SVOM/GRM detection: Wang et al., GCN Circ. 44410;
IPN triangulation: Kozyrev et al., GCN Circ. 44411)
triggered Konus-Wind at T0=85042.824 s UT (23:37:22.824).
The burst light curve shows a multipeaked structure
which starts at ~T0-0.1 s and has a total duration of ~0.6 s.
The emission is seen up to ~3 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB260424_T85042/
As observed by Konus-Wind, the burst
had a fluence of 3.02(-0.30,+0.33)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0+0.198 s,
of 1.89(-0.35,+0.38)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+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 = -0.67(-0.14,+0.16)
and Ep = 756(-131,+170) keV (chi2 = 25/41 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.0
(chi2 = 24/40 dof).
All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.