TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3179
SUBJECT: Konus-Wind observation of GRB 050401
DATE:    05/04/05 14:16:26 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@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:

A long multipeak GRB 050401 (Swift-BAT trigger 113120, GCN 3162,3173)
triggered Konus-Wind at 51611.344 s UT (14:20:11.344).
As observed by Konus-Wind, it had a duration of ~36 s,
fluence (1.93 +/- 0.04)10-5 erg/cm2, peak flux (2.45 +/- 0.12)10-6 
erg/cm2 s (both in the 20 keV - 2 MeV energy range).
We derived two spectra: the first one integrated over three initial
peaks (0 - 16.6 s) and the second integrated over the last, strongest
peak (24.8 - 32 s). Both spectra are well fitted by a GRB (Band) model.

For the 1st spectrum:
the low-energy photon index is alpha = -1.15 +/- 0.16,
the high energy photon index beta = -2.65 +/- 0.31,
the break energy E0 = 156 +/- 45 keV,
and the peak energy Ep = 132 +/- 16 keV.

For the 2nd spectrum:
the low-energy photon index is alpha = -0.83 +/- 0.21,
the high energy photon index beta = -2.37 +/- 0.14,
the break energy E0 = 102 +/- 30 keV,
and the peak energy Ep = 119 +/- 26 keV.

Assuming z = 2.90 (GCN 3176) and a standard cosmology model
with H_0 = 70 km/s/Mpc, Omega_M = 0.3, Omega_\Lambda = 0.7,
the isotropic energy release is E_iso = (3.53 +/- 0.07)1053 erg,
the maximum luminosity is (L_iso)_max = (1.75 +/- 0.09)1053 ers/s,
and the rest-frame peak energies are Ep_rest = (515 +/- 62) keV and
Ep_rest = (464 +/- 101) keV correspondingly for the first and second
spectrum.