GCN Circular 34769
Subject
Konus-Wind detection of GRB 230919A
Date
2023-09-26T13:36:05Z (8 months ago)
From
Y. Temiraev at Ioffe Institute <yuri.temiraev@mail.ioffe.ru>
Via
Web form
Y. Temiraev, D. Svinkin, D. Frederiks, M. Ulanov,
A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline
on behalf of the Konus-Wind team, report:
The short-duration GRB 230919A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 34737;
Scotton et al., GCN Circ. 34750;
AstroSat CZTI detection: Navaneeth et al., GCN Circ. 34742;
Swift/BAT-GUANO detection: DeLaunay et al., GCN Circ. 34747;
IPN triangulation: Kozyrev et al., GCN Circ. 34752)
triggered Konus-Wind at T0=61103.312 s UT (16:58:23.312).
The burst light curve shows a multipeaked structure
which starts at ~T0-0.4 s and has a total duration of ~2.4 s.
The emission is seen up to ~4 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB230919_T61103/
As observed by Konus-Wind, the burst
had a fluence of 8.37(-2.57,+3.19)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0+0.430 s,
of 1.44(-0.72,+0.81)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The spectrum of the burst (measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 4 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.88(-0.25,+0.37)
and Ep = 1452(-629,+1078) keV (chi2 = 69/83 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.1
(chi2 = 69/82 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.