TITLE:   GCN CIRCULAR
NUMBER:  20093
SUBJECT: Konus-Wind observation of GRB 161020B
DATE:    16/10/22 12:28:12 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova@mail.ioffe.ru>

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

The long-duration GRB 161020B
(IPN triangulation: Hurley et al., GCN Circ. 20091)
triggered Konus-Wind at T0=65597.4 s UT (18:13:17.400).

The burst light curve shows a multipeaked structure
started at ~T0-9 s with a total duration of ~45.6 s.
The emission is seen up to 3 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB161020_T65597/

As observed by Konus-Wind, the burst
had a fluence of 5.12(-0.48,+0.54)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+3.136 s,
of 6.42(-1.29,+1.33)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+37.888 s)
is best fit in the 20 keV - 3 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.03(-0.10,+0.11),
the high energy photon index beta = -2.63(-0.59,+0.26),
the peak energy Ep = 186(-19,+21) keV
(chi2 = 69/64 dof)

The spectrum near the maximum count rate
(measured from T0+0.256 to T0+5.120 s)
is best fit in the 20 keV - 3 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.51(-0.10,+0.11),
the high energy photon index beta = -2.72(-0.32,+0.21),
the peak energy Ep = 224(-16,+17) keV
(chi2 = 58/61 dof)

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