GCN Circular 32864
Subject
Konus-Wind detection of GRB 221022B
Date
2022-10-27T12:40:54Z (2 years 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 long-duration GRB 221022B
(Fermi/GBM detection: Fermi GBM team, GCN 32820;
Poolakkil & Meegan, GCN 32830;
AGILE detection: Casentini et al., GCN 32822;
Swift/BAT-GUANO detection: Raman et al., GCN 32823;
AstroSat CZTI detection: Gopalakrishnan et al., GCN 32837;
IPN triangulation: Ridnaia et al., GCN 32842;
GRBAlpha detection: Dafcikova et al., GCN 32844)
triggered Konus-Wind at T0=82557.097 s UT (22:55:57.097).
The burst light curve shows a multipeaked structure
which starts at ~T0-12.1 s and has a total duration of ~51.9 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/GRB221022_T82557/
As observed by Konus-Wind, the burst
had a fluence of 8.19(-0.62,+0.67)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+11.984 s,
of 1.57(-0.24,+0.24)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0+8.448 to T0+43.776 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.68(-0.11,+0.12),
the high energy photon index beta = -2.69(-0.42,+0.23),
the peak energy Ep = 268(-21,+23) keV
(chi2 = 114/98 dof).
The spectrum near the maximum count rate
(measured from T0+8.448 to T0+12.800 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.30(-0.13,+0.15),
the high energy photon index beta = -2.60(-0.24,+0.17),
the peak energy Ep = 299(-24,+27) keV
(chi2 = 104/78 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.