GCN Circular 33720
Subject
Konus-Wind detection of GRB 230430A
Date
2023-05-03T14:19:49Z (a year ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
A.Ridnaia, D. Frederiks, A.Lysenko, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The short-duration GRB 230430A
(Fermi-GBM detection: Fermi GBM Team, GCN 33713;
Mangan & Meegan, GCN 33715;
AstroSat-CZTI detection: Navaneeth et al., GCN 33714;
IPN triangulation: Kozyrev et al., GCN 33718)
triggered Konus-Wind at T0=28040.858 s UT (07:47:20.858).
The burst light curve shows a multipeaked structure
which starts at ~T0-0.2 s and has a total duration of ~0.3 s.
The emission is seen up to ~8 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB230430_T28040/
As observed by Konus-Wind, the burst
had a fluence of 2.24(-0.38,+0.44)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0-0.008 s,
of 2.04(-0.63,+0.69)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+0.192 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 = -0.49(-0.25,+0.31)
and Ep = 704(-180,+254) keV (chi2 = 26/37 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.0
(chi2 = 26/36 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.