[vsnet-grb-info 15640] Konus-Wind observation of GRB 141017A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16929
SUBJECT: Konus-Wind observation of GRB 141017A
DATE:    14/10/20 10:22:18 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred at mail.ioffe.ru>

S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lyssenko, and T. Cline
on behalf of the Konus-Wind team, report:

A long-duration GRB 141017A (Swift-BAT trigger 615672:
Marshall et al., GCN 16919; Markwardt et al., GCN 16927)
triggered Konus-Wind at T0=66374.721 s UT (18:26:14.721),
or ~46 s after the BAT trigger.

The KW light curve shows two episodes of the emission.
The first, weaker episode, which triggered BAT, starts at ~T0-47 s
and ends at ~T0-42 s. The second, much more brighter episode,
which triggered KW, shows a double-peaked pulse from ~T0-3 s to ~T0+7 s.
The emission in this episode is visible up to ~1 MeV.

As observed by Konus-Wind, the burst had a fluence
of 4.0(-0.5,+0.5)x10^-6 erg/cm2, and a 64-ms peak flux,
measured from T0+0.704 s, of 1.8(-0.2,+0.2)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the second episode
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 1.5 MeV range
by the cutoff power law with the following model parameters:
the photon index alpha = -0.89(-0.28,+0.31),
and the peak energy Ep = 97(-10,+12) keV,
chi2 = 73/60 dof.
Fitting this spectrum with the Band model yields the same
values of alpha and Ep and an upper limit on beta of -3.0

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB141017_T66374/

All the quoted errors are at the 95% confidence level.
All the quoted values are preliminary.