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:
The long-duration GRB 141220A (Swift-BAT trigger #621915:
Cummings et al., GCN 17196; Stamatikos et al., GCN 17202;
Fermi-GBM observation: Yu, GCN 17205)
triggered Konus-Wind at T0=21771.666 s UT (06:02:51.666).
The KW light curve shows a single emission episode lasting from ~T0-0.5 s
to ~T0+7.5 s. The emission in this episode is visible up to ~4 MeV.
As observed by Konus-Wind, the burst had a fluence
of 4.7(-0.4,+0.5)x10^-6 erg/cm2, and a 64-ms peak flux,
measured from T0, of 2.2(-0.4,+0.5)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum (measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 15 MeV range
by the cutoff power law with the following model parameters:
the photon index alpha = -0.55(-0.26,+0.30),
and the peak energy Ep = 139(-14,+18) keV,
chi2 = 83/98 dof.
Fitting this spectrum with the Band model yields the same
values of alpha and Ep and an upper limit on beta of -2.0
The Konus-Wind light curve of this GRB is available at
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.