[vsnet-grb-info 5831] Konus-Wind observation of GRB 080319B

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7482
SUBJECT: Konus-Wind observation of GRB 080319B
DATE:    08/03/20 12:04:43 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 bright GRB 080319B (Swift-BAT trigger #306757: Racusin et al., GCN 
7427, Cummings et al., GCN 7462) triggered
Konus-Wind at T0=22370.339 s UT (06:12:50.339).

The burst light curve shows a single complex pulse
with a duration of ~60 s, followed by a long decaying tail
seen up to T-T0 ~200 s in the G1(18-70 keV) and G2(70-300 keV) bands
and even beyond in the G1 band.

Preliminary analysis of the Konus-Wind data
yields the burst fluence of 5.72(-0.13, +0.14)x10^-4 erg/cm2,
and a 64-ms peak flux measured from T0+19.2 s
of (2.17 +/- 0.21)x10^-5 erg/cm2/s
(both in the 20 keV - 7 MeV energy range).

The time-integrated spectrum of the main pulse
(from T0 to T0+59.648 s) can be fitted
(in the 25 keV - 7 MeV range)
by GRBM (Band) model for which:
the low-energy photon index is alpha = -0.822(-0.012, +0.014),
the high energy photon index beta = -3.87(-1.09, +0.44),
the peak energy Ep = 651 (-14, +13) keV (chi2 = 96.2/81 dof).

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

Assuming z = 0.937 (Vreeswijk et al., GCN 7444, 7451) 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 ~1.32x10^54 erg,
the maximum luminosity is (L_iso)_max ~9.67x10^52 erg/s, and
Ep_rest ~1261 keV.

The Konus-Wind light curve of this GRB is available
at http://www.ioffe.rssi.ru/LEA/GRBs/GRB080319_T22370/