TITLE:   GCN CIRCULAR
NUMBER:  45636
SUBJECT: Konus-Wind detection of GRB 260916B (short/hard)
DATE:    26/09/18 16:14:18 GMT
FROM:    Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>

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

The short GRB 260916B (Fermi-GBM detection: Fermi GBM team, GCN 45614; Trigg, GCN 45616;
IPN triangulation: Kozyrev et al., GCN 45630;
Glowbug detection: Cheung et al., GCN 45663)
triggered Konus-Wind (KW) at T0=54667.877 s UT (15:11:07.877).

The burst light curve shows a single pulse,
which starts at ~T0-0.1 s and has a duration of ~0.17 s.
The emission is seen up to ~700 keV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB260916_T54667/

As observed by Konus-Wind, the burst had the total fluence
of (8.82 ± 1.26)x10^-7 erg/cm^2 and a 16-ms peak energy flux,
measured from T0, of (1.30 ± 0.19)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+0.064 s)
is best fitted in the 20 keV - 15 MeV range by a power law with exponential
cutoff (CPL) model dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.00 (-0.33, + 0.38) and Ep = 330(-42,+59) keV, PGstat = 38/50 dof.
Fitting this spectrum by a Band GRB function yields the same values
of alpha and Ep, and only an upper limit on the high energy photon
index beta of -3.3

All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.