[vsnet-grb-info 21513] Konus-Wind observation of GRB 190103B

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23612
SUBJECT: Konus-Wind observation of GRB 190103B
DATE:    19/01/05 19:47:56 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova at mail.ioffe.ru>

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

The  GRB 190103B (Swift detection: Lien et al., GCN 23602;
Markwardt  et al., GCN 23606)
triggered Konus-Wind at T0=75832.010 s UT (21:03:52.010).

The burst light curve shows a double-peaked structure
which starts at ~T0-10 s and has a total duration of ~27 s.
The emission is seen up to ~2 MeV.

As observed by Konus-Wind, the burst
had a fluence of 1.96(-0.08,+0.08)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0+1.408 s,
of 3.87(-0.79,+0.79)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(measured from T0 to T0+22.528 s)
is best fit in the 20 keV - 16 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.17(-0.09,+0.09),
and Ep = 142(-9,+11) keV (chi2 = 97/98 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.88 (chi2 = 97/97 dof).

The spectrum near the peak count rate
(measured from T0+0.256 to T0+6.144 s)
is best fit in the 20 keV - 16 MeV range
by the power law with exponential cutoff model
with  alpha = -0.96(-0.10,+0.10),
and Ep = 157(-10,+11) keV (chi2 = 90/92 dof).
Fitting by the GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.92 (chi2 = 90/91 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB190103_T75832/

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