[vsnet-grb-info 19918] Konus-Wind observation of GRB 171011B

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22005
SUBJECT: Konus-Wind observation of GRB 171011B
DATE:    17/10/12 13:27:38 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 long-duration, very intense GRB 171011B
(IPN triangulation: Hurley et al., GCN Circ. 21998)
triggered Konus-Wind at T0=3931.430 s UT (01:05:31.430).

The burst light curve shows a multipeaked structure
which starts at ~T0-7.3 s and has a total duration of ~18.2 s.
The emission is seen up to ~20 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB171011_T03931/

As observed by Konus-Wind, the burst
had a fluence of 7.02(-0.56,+0.57)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+1.456 s,
of 5.55(-0.61,+0.62)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+10.496 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 = -0.54(-0.12,+0.14),
the high energy photon index beta = -2.28(-0.16,+0.12),
the peak energy Ep = 315(-33,+37) keV
(chi2 = 98/97 dof).

The spectrum near the maximum count rate
(measured from T0+0.256 to T0+1.792 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 = -0.51(-0.11,+0.14),
the high energy photon index beta = -2.59(-0.34,+0.21),
the peak energy Ep = 416(-48,+50) keV
(chi2 = 78/65 dof).

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