TITLE:   GCN CIRCULAR
NUMBER:  28881
SUBJECT: Konus-Wind observation of GRB 201109A
DATE:    20/11/11 18:00:02 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

The short-duration GRB 201109A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 28868;
Malacaria et al., GCN Circ. 28874;
IPN triangulation: Svinkin et al., GCN Circ. 28877)
triggered Konus-Wind at T0=9065.305 s UT (02:31:05.305).

The burst light curve shows a single pulse
which starts at ~T0-0.2 s and has a total duration of ~0.4 s.
The emission is seen up to ~2 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB201109_T09065/

As observed by Konus-Wind, the burst
had a fluence of 9.79(-1.84,+2.96)x10^-7 erg/cm2,
and a 16-ms peak flux, measured from T0+0.018 s,
of 6.13(-2.75,+3.42)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+0.192 s)
is best fit in the 20 keV - 5 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.96(-0.51,+0.65)
and Ep = 244(-73,+249) keV (chi2 = 13/16 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -1.9
(chi2 = 13/15 dof).

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