GCN Circular 40889
Subject
Konus-Wind detection of GRB 250627A
Event
Date
2025-07-02T16:17:20Z (4 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 250627A
(SVOM-GRM detection: Wang et al., GCN 40871;
Insight-HXMT detection: Wang et al., GCN 40872;
IPN triangulation: Kozyrev et al., GCN 40888)
triggered Konus-Wind at T0=60377.861 s UT (16:46:17.861).
The burst light curve shows a multipeaked structure
which starts at ~T0-0.3 s and has a total duration of ~1.1 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/GRB250627_T60377/
As observed by Konus-Wind, the burst
had a fluence of 9.65(-1.16,+1.29)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0+0.420 s,
of 2.60(-0.49,+0.52)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+8.448 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 = -0.31(-0.21,+0.25)
and Ep = 874(-128,+160) keV (chi2 = 73/76 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.7
(chi2 = 73/75 dof).
All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.