TITLE:   GCN CIRCULAR
NUMBER:  31086
SUBJECT: Konus-Wind detection of GRB 211107B
DATE:    21/11/16 14:29:21 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

D. Svinkin, S. Golenetskii, D. Frederiks, M. Ulanov,
A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 211107B
(Swift-BAT detection: Tohuvavohu, GCN Circ. 31057)
triggered Konus-Wind at T0=62836.647 s UT (17:27:16.647).

The burst light curve shows the initial pulse,
which starts at ~T0-3.7 s and has a total duration of ~24 s,
followed by a weaker emission seen up to T0+205 s.
The emission is seen up to ~1 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB211107_T62836/

As observed by Konus-Wind, the burst
had a fluence of 8.95(-1.76,+1.88)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0-0.108 s,
of 1.42(-0.68,+0.69)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The spectrum of the initial pulse
(measured from T0 to T0+16.640 s)
is best fit in the 20 keV - 2 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.88(-0.40,+0.47)
and Ep = 152(-26,+41) keV (chi2 = 51/56 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.7
(chi2 = 51/55 dof).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.