TITLE: GCN CIRCULAR NUMBER: 31022 SUBJECT: Konus-Wind detection of GRB 211023A DATE: 21/10/28 21:24:26 GMT FROM: Anna Ridnaia at Ioffe Institute ridnaia@mail.ioffe.ru
A. Ridnaia, D. Frederiks, S. Golenetskii, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report:
The long-duration GRB 211023A (Fermi-GBM detection: Fermi GBM Team, GCN 30958; Lesage et al., GCN 30965; Fermi-LAT detection: Di Lalla et al., GCN 30961; AGILE detection: Ursi et al., GCN 30969) triggered Konus-Wind at T0=47199.142 s UT (13:06:39.142).
The burst light curve shows a multipeaked structure started at ~T0-65.3 s with a total duration of ~207.9 s. The emission is seen up to ~6 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB211023_T47199/
As observed by Konus-Wind, the burst had a fluence of 1.13(-0.04,+0.05)x10^-4 erg/cm2, and a 64-ms peak flux, measured from T0+6.368 s, of 5.12(-1.01,+1.01)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst (measured from T0 to T0+103.936 s) is best fit in the 20 keV - 6 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -1.85(-0.03,+0.03) and Ep = 122(-12,+15) keV (chi2 = 100/79 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.4 (chi2 = 99/78).
The spectrum near the maximum count rate (measured from T0+5.888 to T0+10.496 s) is best fit in the 20 keV - 6 MeV range by a power law with exponential cutoff model with alpha = -1.27(-0.06,+0.06) and Ep = 267(-22,+27) keV (chi2 = 76/72 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.6 (chi2 = 75/71).
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.