GCN Circular 31162
Subject
Konus-Wind detection of GRB 211130A
Event
Date
2021-12-03T17:19:17Z (5 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 211130A
(Fermi GBM Final Real-time localization: The Fermi GBM team, GCN 31151;
BALROG localization: Kunzweiler et al., GCN 31152;
IPN triangulation: Kozyrev et al., GCN 31161)
triggered Konus-Wind at T0=54992.505 s UT (15:16:32.505).
The burst light curve starts with a smooth pulse, which was followed,
after a period of low-level emission, by a more intense, multi-peaked
emission complex. The total burst duration is ~21.4 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/GRB211130_T54992/
As observed by Konus-Wind, the burst
had a fluence of 9.57(-0.68,+0.75)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0+13.456 s,
of 8.39(-2.23,+2.99)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+16.640 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 = -0.54(-0.24,+0.27)
and Ep = 164(-15,+19) keV (chi2 = 82/75 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.5
(chi2 = 82/74).
The spectrum near the maximum count rate
(measured from T0+8.448 to T0+16.640 s)
is best fit in the 20 keV - 6 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.40(-0.34,+0.47),
the high energy photon index beta = -2.69(-1.55,+0.43),
the peak energy Ep = 177(-31,+34) keV
(chi2 = 56/73 dof).
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.