GCN Circular 2693
Subject
Very bright burst detected from SGR 1806-20
Date
2004-09-04T09:25:41Z (22 years ago)
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 Konus-Wind team,
G. Ricker, J-L Atteia, N. Kawai, D. Lamb, S. Woosley, J. Doty, R.
Vanderspek, J. Villasenor, G. Crew, N. Butler, J.G. Jernigan, F.
Martel, G. Prigozhin, A. Dullighan, J. Braga, R. Manchanda, G.
Pizzichini, Y. Shirasaki, C. Graziani, M. Matsuoka, T. Tamagawa, T.
Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, T. Donaghy, C.
Barraud, M. Boer, J-F Olive, and J-P Dezalay, on behalf of the HETE GRB
team, and
K. Hurley on behalf of the IPN team report:
A very bright SGR burst was detected by Konus-Wind on August 28
at 42581.338 s UT.
This burst also triggered HETE at 42569.952 s UT (H3514).
We have triangulated it to an annulus centered at
RA(2000) = 317.135 deg, Decl(2000) = -17.624 deg,
whose radius is 42.448 +/- 1.601 deg (3 sigma).
As this annulus includes the position of SGR 1806-20
and Konus ecliptic latitude response indicates
that the burst source lays near ecliptic plane,
we believe that SGR 1806-20 is the source of this event.
As observed by Konus-Wind, the burst had a duration of 0.7 s, a
fluence ~4.0x10^-5 erg/cm^2, and a peak flux ~1x10^-4 erg/cm^2 s
(both in 20-200 keV range).
The value of the spectral parameter kT for an OTTB spectral model
(dN/dE ~ E^{-1} exp(-E/kT)) was 26 keV.
This burst is the brightest one from this SGR detected
so far by Konus-Wind. It is stronger, than the burst on 040825
(GCN 2665) by a factor of about 1.7 in fluence
and peak flux.