GCN Circular 38727
Subject
Konus-Wind detection of GRB 241228A
Date
2024-12-30T11:44:36Z (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 long-duration GRB 241228A
(Swift-BAT detection: D'Elia et al., GCN 38681;
Sadaula et al., GCN 38701;
Fermi-GBM detection: Scotton & Meegan, GCN 38695)
triggered Konus-Wind at T0=14233.924 s UT (03:57:13.924).
The burst light curve shows a two-peak structure
which starts at ~T0-0.2 s and has a total duration of ~5.1 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/GRB241228_T14233/
As observed by Konus-Wind, the burst
had a fluence of 3.35(-0.17,+0.18)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0+1.760 s,
of 1.74(-0.01,+0.01)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 = -0.88(-0.24,+0.26)
and Ep = 75(-5,+5) keV (chi2 = 96/81 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 = 96/80 dof).
All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.