GCN Circular 34638
Subject
Konus-Wind detection of GRB 230906A (short)
Date
2023-09-07T16:26:29Z (a year ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
Via
legacy email
D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The short GRB 230906A (Fermi GBM detection: the Fermi GBM team, GCN Circ 34631;
IPN triangulation: Kozyrev et al., GCN Circ 34637)
triggered Konus-Wind (KW) at T0=46507.186 s UT (12:55:07.186).
The burst light curve shows a multi-peaked structure
which starts at ~T0-0.256 s and has a duration of ~0.29 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/GRB230906_T46507/
As observed by Konus-Wind, the burst had
a total fluence of (2.55 ± 0.23)x10^-6 erg/cm^2 and
a 16-ms peak energy flux, measured from T0,
of (3.48 ± 0.34)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
The spectrum of the burst (measured from T0 to T0+0.128 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 = -0.56(-0.13,+0.14) and Ep = 522(-56,+65) keV (chi2 = 27/35 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 -2.1 (chi2 = 27/34 dof).
All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.