TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4183
SUBJECT: Konus-Wind observation of GRB 051028
DATE:    05/10/31 11:17:25 GMT
FROM:    Valentin Pal'shin at Ioffe Inst  <val@mail.ioffe.ru>

S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and
T. Cline on behalf of the Konus-Wind team report:

The GRB 051028 (HETE trigger #3951; Hurley et al., GCN 4172) 
triggered Konus-Wind at T0=48967.159 s UT (13:36:07.159)

The time-integrated spectrum of the GRB (from T0 to T0+8.448 sec)
is well fitted (in the 20 keV - 2 MeV range)
by a power law with exponential cutoff model:
dN/dE ~ E^(-alpha) * exp(-E/E0)
with alpha = 0.73 (-0.26, +0.22)
and E0 = 236 (-68, +110) keV (chi^2 = 61/62 dof).
The peak energy Ep = 298 (-50, +73) keV.
It can also be fitted by GRBM (Band) model for which:
the low-energy photon index is alpha = -0.47 (-0.37, +0.57),
the high energy photon index beta < -1.97,
the break energy E0 = 150 (-69, +118) keV.


As observed by Konus-Wind the burst had a duration ~12 sec,
fluence 6.78(-1.08, +0.61)x10^-6 erg/cm2 and
peak flux on 256-ms time scale 1.29(-0.24, +0.15)x10^-6 erg/cm2/sec
(both in the 20 keV - 2 MeV energy range).

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