GCN Circular 45806
Subject
Konus-Wind detection of GRB 260919A / EP 260920a
Event
Date
2026-10-03T16:26:27Z (2 days ago)
From
Valentina Panteleeva at Ioffe Institute <panteleevav228@gmail.com>
Via
Web form
V. Panteleeva, 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-duration GRB 260919A / EP 260920a
(EP-WXT detection: Ni et al., GCN 45649;
IPN triangulation: Svinkin et al., GCN 45792)
was detected by Konus-Wind (KW) in the waiting mode
at about T0=85725 s UT (23:48:45).
A Bayesian block analysis of the KW waiting mode data
in the 20-300 keV band reveals a >20 sigma count rate
increase in the interval from T0+44 s to T0+209 s.
The total burst duration is 165 s.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB260919_T85725/
The total burst fluence is 1.32(-0.20,+0.38)x10^-5 erg/cm^2,
and the 2.944 s peak energy flux, measured from T0+144.341 s,
is 2.05(-0.36,+0.64)x10^-7 erg/cm^2/s.
(both in the 10 keV - 1 MeV energy range).
The time-integrated spectrum of the burst,
measured from T0+44.245 s to T0+209.109 s,
can be described by a power law with exponential cutoff (CPL) model
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha > -1.3 and Ep = 109(-14,+46) keV.
The spectrum near the peak count rate,
measured from T0+132.565 s to T0+147.285 s,
can be described by a CPL model with
alpha > -0.3 and Ep = 105(-4,+53) keV.
All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.