[vsnet-grb-info 25812] Konus-Wind detection of GRB 200605A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  27912
SUBJECT: Konus-Wind detection of GRB 200605A
DATE:    20/06/09 12:12:44 GMT
FROM:    Anna Ridnaia at Ioffe Institute  <ridnaia at 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 200605A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 27892;
IPN triangulation: Hurley et al., GCN Circ. 27900;
CALET-GRBM detection: Kawakubo et al., GCN Circ. 27911)
triggered Konus-Wind at T0=65858.111 s UT (18:17:38.111).

The burst light curve shows a multipeaked structure
which starts at ~T0 and has a total duration of ~0.4 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/GRB200605_T65862/

As observed by Konus-Wind, the burst
had a fluence of 3.63(-0.51,+0.60)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0+0.016 s,
of 2.48(-0.69,+0.75)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+0.256 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 = -0.82(-0.20,+0.23)
and Ep = 744(-174,+273) keV (chi2 = 23/28 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.2
(chi2 = 23/27 dof).

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