[vsnet-grb-info 20816] Konus-Wind observation of GRB 180703B

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22914
SUBJECT: Konus-Wind observation of GRB 180703B
DATE:    18/07/06 11:56:57 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred at mail.ioffe.ru>

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

GRB 180703B (IPN Triangulation: Hurley et al., GCN 22908;
Fermi-LAT detection: Racusin et al., GCN 22884;
Fermi-GBM detection: Poolakkil & Meegan, GCN 22897)
triggered Konus-Wind at T0=82008.633 s UT (22:46:48.633)

The burst light curve shows two prominent peaks,
with a total duration of ~2.0 s.
The emission in the main peak is seen up to ~2 MeV.

As observed by Konus-Wind, the burst had a fluence of
(6.4 ± 0.4)x10^-6 erg/cm2 and a 64-ms peak energy flux,
measured from T0+1.088, of (1.60 ± 0.09)x10^-5 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 2 MeV range by a cutoff power-law
(CPL) function with the following model parameters:
the photon index alpha = -0.74(-0.18,+0.19),
and the peak energy Ep = 131(-9,+11) keV,
chi2 = 55/57 dof.
Fitting this spectrum with the GRB (Band) function yields
the same alpha and Ep, and only an upper limit on beta (<-3.3).


The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180703_T82008/

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