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GCN Circular 2354

Subject
IPN detection of continued activity from SGR1806-20
Date
2003-08-18T23:28:52Z (21 years ago)
From
Kevin Hurley at UCBerkeley/SSL <khurley@sunspot.ssl.berkeley.edu>
K. Hurley and T. Cline, on behalf of the Ulysses and Mars Odyssey GRB
teams,

I. Mitrofanov, S. Charyshnikov, V. Grinkov, A. Kozyrev, M. Litvak, and
A. Sanin, on behalf of the HEND-Odyssey GRB team, and

W. Boynton, C. Fellows, K. Harshman, C. Shinohara and R. Starr, on
behalf of the GRS-Odyssey GRB team, report:

Ulysses and Mars Odyssey (HEND) observed this unusually long SGR
burst.  As observed by Ulysses, it had a duration of approximately 1
second, a 25-100 keV fluence of approximately  7.3E-06 erg/cm2, and a
peak flux of approximately  1.9E-05 erg/cm2 s over 0.25 seconds.

We have triangulated it to a preliminary annulus centered at RA,
Decl(2000)=340.644, -22.919 degrees, whose radius is 63.096 +/-0.013
degrees (3 sigma).  As the center line of this annulus passes 0.003
degrees from the position of SGR1806-20, we consider it most likely
that this event originated from that SGR.  If so, the Earth-crossing
time was 50231 seconds.  However, due to the present configuration of
the IPN, Ulysses/Mars, Mars/Earth, and Ulysses/Earth annuli which are
consistent with the position of SGR1806-20 will also be consistent with
portions of the error circle for the possible new SGR, 1808-20 (GCN
2351).  Depending on the exact position of SGR1808-20, however, the
converse is not necessarily true.  Thus it may be possible to confirm
the existence of this new source with the IPN if it bursts again.  The
situation is illustrated with a map which has been posted at
ssl.berkeley.edu/ipn3/030818.
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