TITLE:   GCN CIRCULAR
NUMBER:  28723
SUBJECT: Konus-Wind detection of GRB 201020B
DATE:    20/10/21 16:18:09 GMT
FROM:    Anna Ridnaia at Ioffe Institute  <ridnaia@mail.ioffe.ru>

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

The long-duration GRB 201020B
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 28702,
Malacaria & Meegan, GCN Circ. 28710;
AGILE detection: Ursi et al., GCN Circ. 28714;
Fermi-LAT detection: Arimoto et al., GCN Circ. 28716)
triggered Konus-Wind at T0=63237.477 s UT (17:33:57.477).

The burst light curve shows a multipeaked structure
started at ~T0-5.6 s with a total duration of ~53.7 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/GRB201020_T63237/

As observed by Konus-Wind, the burst
had a fluence of 4.72(-0.61,+0.70)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+8.016 s,
of 1.38(-0.25,+0.25)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+50.432 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 = -1.12(-0.09,+0.10),
the high energy photon index beta = -2.55(-0.56,+0.26),
the peak energy Ep = 193(-23,+23) keV
(chi2 = 72/97 dof).

The spectrum near the maximum count rate
(measured from T0+7.424 to T0+8.448 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 = -0.85(-0.13,+0.14),
the high energy photon index beta = -2.78(-3.16,+0.36),
the peak energy Ep = 259(-35,+44) keV
(chi2 = 41/52 dof).

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