TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5518
SUBJECT: Konus-Wind observation of GRB 060904A
DATE:    06/09/04 13:36:59 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 most intense part of the long GRB 060904A
(Swift-BAT trigger #227996;  Grupe et al., GCN 5502;
Krimm et al., GCN 5516)
triggered Konus-Wind at T0=3853.821 s UT (01:04:13.821).

As observed by Konus-Wind the burst emission
started at T-T0 ~-56 s, peaked at T-T0 ~0 s,
and ended at T-T0 ~26 s, so the total burst duration
is ~80 s.
The burst fluence is 1.59(-0.21, +0.40)x10^-5 erg/cm2,
and the 256-ms peak flux measured from T0-0.128 s
1.38(-0.33, +0.46)x10^-6  erg/cm2/s
(both in the 20 keV - 2 MeV energy range).

The spectrum of the main pulse
(from T0 to T0+16.64 s)
is well fitted (in the 20 keV - 2 MeV range)
by GRBM (Band) model for which:
the low-energy photon index is alpha = -1.00(-0.17, +0.23),
the high energy photon index beta = -2.57(-1.00, 0.37),
the break energy E0 = 163 (-54, +65) keV (chi2 = 40/61 dof).
The peak energy Ep = 163 +/- 31 keV.

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