[vsnet-grb-info 19178] Konus-Wind observation of GRB 170306B

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20831
SUBJECT: Konus-Wind observation of GRB 170306B
DATE:    17/03/07 11:39:11 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 170306B (Fermi-LAT detection: Omodei et al., GCN 20826;
Fermi-GBM detection: Veres et al., GCN 20827)
triggered Konus-Wind at T0=50850.920 s UT (14:07:30.920)

The light curve shows a multi-peaked structure
with a total duration of ~25 s.
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst had a fluence of
(3.4 ± 0.4)x10^-5 erg/cm2 and a 64-ms peak energy flux,
measured from T0+3.712, of (4.1 ± 0.6)x10^-6 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+22.528 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 = -0.58 (-0.13,+0.16),
the high energy photon index beta = -2.62 (-0.61,+0.28),
the peak energy Ep = 237 (-27,+27) keV,
chi2 = 105/97 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 = -0.40 (-0.11,+0.12),
the high energy photon index beta = -2.70 (-0.84,+0.29),
the peak energy Ep = 214 (-24,+30) keV,
chi2 = 120/97 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170306_T50850/

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