[vsnet-grb-info 20218] Konus-Wind observation of GRB 180103A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22314
SUBJECT: Konus-Wind observation of GRB 180103A
DATE:    18/01/10 16:49:22 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin at mail.ioffe.ru>

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

The bright long-duration GRB 180103A
(Swift-BAT detection: Beardmore et al., GCN Circ. 22305;
AstroSat-CZTI detection: Sharma et al., GCN Circ. 22310)
triggered Konus-Wind at T0=4122.424 s UT (01:08:42.424).

The burst light curve shows a multipeaked structure
which starts at ~T0-19.5 s and has a total duration of ~237 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/GRB180103_T04122/

As observed by Konus-Wind, the burst
had a fluence of 3.41(-0.36,+0.33)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+91.200 s,
of 1.86(-0.27,+0.26)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+219.136 s)
is best fit in the 20 keV - 20 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.31(-0.06,+0.06),
the high energy photon index beta = -2.30(-0.30,+0.15),
the peak energy Ep = 282(-33,+40) keV
(chi2 = 81/96 dof).

The spectrum near the maximum count rate
(measured from T0+81.664 to T0+93.952 s)
is best fit in the 20 keV - 20 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -1.00(-0.04,+0.04),
the high energy photon index beta = -2.81(-0.99,+0.31),
the peak energy Ep = 589(-48,+52) keV
(chi2 = 107/97 dof).

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