[vsnet-grb-info 18971] Konus-Wind observation of GRB 170115B

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20476
SUBJECT: Konus-Wind observation of GRB 170115B
DATE:    17/01/17 09:01:14 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 170115B (Fermi-GBM detection: Hamburg & Meegan, GCN 20463;
Fermi-LAT detection: McEnery et al., GCN 20464;
AstroSat CZTI observation: Sharma et al., GCN 20466;
POLAR observation: Xiao et al., GCN 20469;
AGILE detection:  Verrecchia et al., GCN 20474;
IPN triangulation: Hurley et al., GCN 20475)
triggered Konus-Wind at T0=64155.241 s UT (17:49:15.241).

The light curve shows a bright, hard, multi-peaked pulse
followed by a weaker emission; the total duration of the burst is ~50 s.
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst had a fluence of
(1.26 ± 0.12)x10^-4 erg/cm2 and a 64-ms peak energy flux,
measured from T0+0.512, of (3.1 ± 0.2)x10^-5 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+38.144 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 = -0.86 (-0.06,+0.06),
the high energy photon index beta = -2.49 (-0.90,+0.31),
the peak energy Ep = 1114 (-156,+180) keV,
chi2 = 94/97 dof.

The spectrum near the peak count rate (measured from T0 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 = -0.61 (-0.08,+0.08),
the high energy photon index beta = -2.59 (-1.30,+0.32),
the peak energy Ep = 1278 (-175,+223) keV,
chi2 = 94/97 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170115_T64155/

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