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GCN Circular 3343

Renewal of SGR 1806-20 activity
2005-05-03T15:18:35Z (19 years ago)
Valentin Pal'shin at Ioffe Inst <>
S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks
on behalf of Konus-Wind and Helicon/Coronas-F teams, and
T. Cline on behalf of the Konus-Wind team,
A. Rau, A. von Kienlin, G. Lichti on behalf of the INTEGRAL SPI-ACS
GRB team report:

On May 2 Konus-Wind detected two SGR-like bursts in the trigger mode.

The first one triggered Konus-Wind at 5376.421 s UT (01:29:36.421). 
It was also detected by INTEGRAL SPI-ACS.
Because the burst was soft, the SPI-ACS response is very weak,
and precise triangulation of this burst is not possible.
We conservatively estimated that the time delay was 3.6 +/- 0.4 s
which is consistent with the expected time delay for SGR 1806-20
(=3.651 s). Additionaly, the Konus ecliptic latitude response
indicates that the burst source is near the ecliptic plane,
so we believe that this burst originated from SGR 1806-20.
The burst is unusually long with a duration of ~4.5 s,
but relatively weak.
As observed by Konus-Wind, the burst had a fluence  ~2.0x10^-5 erg/cm2,
and a peak flux ~6x10^-6 erg/cm2 s (both in 20-200 keV range).
The time-integrated spectrum of the burst is well fitted by the OTTB
spectral model:
dN/dE ~ E^{-1} exp(-E/kT) with kT = 18 +/- 1 keV,
which is typical for this SGR.

The second burst triggered Konus-Wind 
at  18502.741 s  UT (05:08:22.741). 
As observed by Konus-Wind, it had a duration ~1 s,
a fluence  ~4.5x10^-6 erg/cm2, a peak flux ~3.7x10^-6 erg/cm2 s
(both in 20-200 keV range).

Another two SGR-like bursts (soft and short) were observed 
by Konus-Wind in the background mode 
at 5021 s UT (01:23:41) and 16740 s UT (04:39:00) (also on May 2).
The last burst was also detected by Helicon-Corronas-F 
in the background mode.
The estimated time delay is consistent with SGR 1806-20 position.

The Konus ecliptic latitude response indicates
that the source of all these bursts is near the ecliptic plane,
so we suppose, that they are also originated from SGR 1806-20.
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