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GCN Circular 1045

Subject
Possible precursor to the SGR1900+14 giant burst
Date
2001-04-20T19:48:21Z (23 years ago)
From
Kevin Hurley at UCBerkeley/SSL <khurley@sunspot.ssl.berkeley.edu>
K. Hurley, on behalf of the Ulysses GRB team, and E. Montanari, C. Guidorzi,
F. Frontera, and M. Feroci, on behalf of the BeppoSAX GRBM team, report:

We have identified a likely precursor to the giant flare from
SGR1900+14 (GCN 1041, 1043) in the Ulysses data.  This event
occurred on April 17, 2001, ~42184 s at Ulysses, and if it was
indeed from SGR1900+14, its Earth-crossing time would have
been ~42332 s.  This burst was ~50 s long, and its time history
resembles that of the April 18 event, although it is considerably
less intense.  Its 25-100 keV fluence was ~2.3x10^-5 erg/cm^2,
and its peak flux over 0.5 s was ~1.5x10^-6 erg/cm^2 s.  Due to
a high solar proton background, these numbers are subject to more
than the usual uncertainties.  As SGR1900+14 was Earth-blocked
at BeppoSAX, it did not observe this event, and there is no
localization data available.

The time history has been posted at ssl.berkeley.edu/ipn3/010417.
Also, we note that the time history of the April 18 event, posted
at ssl.berkeley.edu/ipn3/010418, was incorrectly labelled "Counts/
0.5 s".  The label should have read "Counts/Second".  A corrected
plot has been posted.

Searches are underway through the Ulysses data for more possible
events from this source.
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