GCN Circular 32258
Subject
Konus-Wind detection of GRB 220623A
Event
Date
2022-06-24T12:32:17Z (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 220623A (Swift detection: Sbarufatti et al., GCN Circ. 32243;
AstroSat-CZTI detection: Gopalakrishnan et al., GCN Circ 32246;
AGILE detection: Ursi et al., GCN Circ 32247)
triggered Konus-Wind (KW) at T0=25447.564 s UT (07:04:07.564).
The burst light curve shows a bright, double-peaked structure
which starts at ~T0-0.2 s and has a total duration of ~15 s.
A weaker emission in visible in the KW lc until ~T0+50 s.
The emission at the bright phase of the event is seen up to ~2.5 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB220623_T25447/
As observed by Konus-Wind, the burst had
a fluence of (2.5 �� 0.3)x10^-5 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 0.064 s,
of (8.8 �� 0.8)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum (measured from T0 to T0+49.408 s)
is best 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 = -1.13(-0.11,+0.12) and Ep = 869(-224,+363) 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 -2.6 (chi2 = 93/97 dof).
The spectrum near the peak count rate (measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 15 MeV range by a CPL function
with alpha = -0.82(-0.09,+0.10) and Ep = 910(-136,+177) keV (chi2 = 86/98 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 -2.9 (chi2 = 86/97 dof).
All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.