TITLE:   GCN CIRCULAR
NUMBER:  27407
SUBJECT: Konus-Wind observation of GRB 200313B
DATE:    20/03/18 13:30:13 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 short-duration GRB 200313B
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 27379;
IPN triangulation: Svinkin et al., GCN Circ. 27386)
triggered Konus-Wind at T0=39435.021 s UT (10:57:15.021).

The burst light curve shows a single pulse
which starts at ~T0-0.5 s and has a total duration of ~1.4 s.
The emission is seen up to ~1 MeV.

As observed by Konus-Wind, the burst
had a fluence of 6.83(-2.07,+3.49)x10^-7 erg/cm2,
and a 16-ms peak flux, measured from T0-0.016 s,
of 1.90(-1.18,+1.53)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+0.256 s)
is best fit in the 20 keV - 1 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.71(-0.91,+1.65)
and Ep = 145(-55,+252) keV (chi2 = 31/26 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -1.8
(chi2 = 31/25 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB200313_T39435/

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