TITLE:   GCN CIRCULAR
NUMBER:  27796
SUBJECT: Konus-Wind detection of short/hard GRB 200521A
DATE:    20/05/23 22:45:12 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

The short GRB 200521A
(AGILE detection: Verrecchia et al., GCN Circ. 27776;
CALET-GBM detection: Yoshida et al., GCN Circ. 27777;
CGBM-SPI-ACS triangulation: Sakamoto et al., GCN Circ. 27790;
IPN triangulation: Svinkin et al., GCN Circ. 27795)
triggered Konus-Wind (KW) at T0=44201.268 s UT (12:16:41.268).

The light curve of the burst shows a single pulse
with a total duration of ~0.3 s.
The emission is seen up to ~10 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB200521_T44201/

As observed by Konus-Wind, the burst had
a fluence of (1.28 +/- 0.15)x10^-5 erg/cm^2 and
a 16-ms peak energy flux, measured from T0+0.080 s,
of (7.38 +/- 0.87)x10^-5 erg/cm^2/s
(both in the 20 keV - 10 MeV energy range).

The spectrum of the burst (measured from T0 to T0+0.256 s)
is well fitted in the 20 keV - 15 MeV range
by a cutoff power-law (CPL) function with the following model
parameters: the photon index alpha = -0.26(-0.16,+0.18),
and the peak energy Ep = 1358(-170,+196) keV, chi2 = 46/61 dof.
Fitting this spectrum with a GRB (Band) function yields
nearly the same alpha and Ep, and an upper limit on beta of -2.7.

All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.