[vsnet-grb-info 2239] Konus-Wind observation of GRB 051008

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4078
SUBJECT: Konus-Wind observation of GRB 051008
DATE:    05/10/09 18:21:49 GMT
FROM:    Valentin Pal'shin at Ioffe Inst  <val at 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 051008 (Swift-BAT trigger #158855; 
Marshall et al., GCN 4069; Parsons et al., GCN 4075)
triggered Konus-Wind at T0=59600.762 s  UT (16:33:20.762).

The Konus-Wind light curve shows a wide multipeaked pulse
followed by a long decaying tail seen up to ~T0+250 sec.
An additional smaller peak is clearly seen at ~T0+213 sec (to ~T0+222
sec).
The start time of the emission is ~T0-25 sec.
The total burst duration is ~280 sec.

As observed by Konus-Wind it had a fluence ~5.4x10-5 erg/cm2,
peak flux on 256-ms time scale ~9.6x10-6  erg/cm2/sec
(both in the 20 keV - 4 MeV energy range).

The spectrum integrated over the most intense part of the GRB
(from T0 to T0+8.192 sec) is well fitted (in the 20 keV - 4 MeV range)
by a power law with exponential cutoff model:
dN/dE ~ E^(-alpha) * exp(-E/E0)
with alpha = 0.975 (-0.086, +0.078)
and E0 = 844 (-175, +238) keV.
The peak energy Ep = 865 (-136, +178) keV.

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

Hence, the GRB 051008 is a long hard burst.

The Konus-Wind light curve of this GRB can be seen
at http://www.ioffe.rssi.ru/LEA/GRBs/GRB051008_T59600/