[vsnet-grb-info 20255] Konus-Wind observation of GRB 180113C

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22351
SUBJECT: Konus-Wind observation of GRB 180113C
DATE:    18/01/16 10:25:27 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred at mail.ioffe.ru>

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

The long GRB 180113C (Fermi-GBM detection: Veres et al., GCN 22344;
Insight-HXMT/HE observation: Li et al., GCN 22343;
IPN Triangulation: Hurley et al., GCN 22349)
triggered Konus-Wind at T0=36129.524 s UT (10:02:09.524)

The burst light curve shows a bright, multi-peaked pulse
with a total duration of ~80 s.
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst had a fluence of
(2.9 ± 0.1)x10^-4 erg/cm2 and a 64-ms peak energy flux,
measured from T0+6.400, of (3.1 ± 0.3)x10^-5 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+37.888 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.78 (-0.05,+0.05),
the high energy photon index beta = -2.14 (-0.06,+0.05),
the peak energy Ep = 368 (-22,+24) keV,
chi2 = 108/96 dof.

The spectrum near the peak count rate (measured from T0+6.400 s
to T0+6.912 s) is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.35 (-0.16,+0.20),
the high energy photon index beta = -2.09 (-0.18,+0.13),
the peak energy Ep = 429 (-76,+85) keV,
chi2 = 59/63 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB80113_T36129/

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