TITLE:   GCN CIRCULAR
NUMBER:  28277
SUBJECT: Konus-Wind observation of GRB 200815A
DATE:    20/08/21 13:06:17 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

Konus-Wind observation of GRB 200815A

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 200815A
(CALET-GBM detection: Kobayashi et al., GCN Circ. 28255;
IPN triangulation: Hurley et al., GCN Circ. 28274)
triggered Konus-Wind at T0=75768.265 s UT (21:02:48.265).

The burst light curve shows a single pulse
which starts at ~T0-0.03 s and has a total duration of ~0.2 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/GRB200815_T75768/

As observed by Konus-Wind, the burst
had a fluence of 3.04(-0.39,+0.43)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0+0.038 s,
of 3.33(-0.73,+0.77)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+0.192 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.37(-0.23,+0.27)
and Ep = 516(-89,+116) keV (chi2 = 35/45 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.3
(chi2 = 35/44 dof).

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