TITLE: GCN CIRCULAR NUMBER: 34769 SUBJECT: Konus-Wind detection of GRB 230919A DATE: 23/09/26 13:36:05 GMT FROM: Y. Temiraev at Ioffe Institute yuri.temiraev@mail.ioffe.ru
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.
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