GCN Circular 32121
Subject
Konus-Wind detection of GRB 220524A
Event
Date
2022-05-26T12:32:42Z (3 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
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 GRB 220524A (IPN triangulation: Kozyrev et al., GCN 32115)
triggered Konus-Wind (KW) at T0=35587.191 s UT (09:53:07.191).
The burst light curve shows a multi-peaked structure,
which starts at ~T0-0.5 s and has a total duration of ~2.5 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/GRB220524_T35587/
As observed by Konus-Wind, the burst had
a fluence of (4.0 �� 0.6)x10^-6 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 2.048 s,
of (6.1 �� 1.0)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
A time-averaged spectrum of the burst (measured from T0 to T0+8.448 s)
is well fit in the 20 keV - 15 MeV range
by a power law with exponential cutoff (CPL) model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -1.22(-0.23,+0.27) and Ep = 186(-38,+63) keV (chi2 = 93/98 dof).
Fitting this spectrum by a Band function yields the same values of alpha and Ep,
and an upper limit on the high energy photon index beta of -2.2 (chi2 = 92/97 dof).
All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.