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GCN Circular 1253

IPN/HETE Detection of Bursts from SGR1900+14
2002-02-19T21:48:24Z (22 years ago)
Kevin Hurley at UCBerkeley/SSL <>
K. Hurley, on behalf of the Ulysses GRB team;

G. Ricker, D. Lamb, S. Woosley, G. Crew, J. Doty, G.  Monnelly, J.
Villasenor, R. Vanderspek, N.  Butler, J.G. Jernigan, A. Levine, F.
Martel, E. Morgan, G.  Prigozhin, J. Braga, R. Manchanda, G.
Pizzichini, N. Kawai, M. Matsuoka, Y. Shirasaki, T. Tamagawa, K. Torii,
T.  Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, T. Donaghy, C.
Graziani, T. Tavenner, J-L Atteia, M. Boer, J-F Olive, and J-P Dezalay,
on behalf of the HETE Team; 

M. Feroci, F. Frontera, C. Guidorzi, and E. Montanari, on behalf of the
BeppoSAX GRBM team; and

T. Cline, on behalf of the Ulysses and HETE GRB teams, report:

A resurgence of activity from the soft gamma repeater SGR1900+14
has been detected by Ulysses and HETE-FREGATE, as evidenced
by the detection of the following short bursts:

Date		Time at	   Time at 	Duration,	Fluence,
		Ulysses    HETE            s.           erg/cm^2
							25-100 keV

February 17	74060 s	   Not observed   .032		10^-7
February 18	03916 s	   Not observed   .032		4x10^-7
February 18	10143 s	   Not observed   .12		2x10^-6
February 18	16661 s	   Not observed	  .25           10^-6		
February 18	21936 s	   Not observed   .22		1.4x10^-6
February 18	22632 s	   23134 s	  .15		1.2x10^-4

Triangulation of the last event on February 18 gives an annulus
consistent with the position of SGR1900+14.  This SGR is presently ~130
degrees off-axis for FREGATE and the other HETE instruments.  However,
the last burst was ~100 times more intense than the preceding ones,
which explains why it alone could have been detected through the
collimator.  Assuming that the other events were indeed from SGR1900
(because of their properties and proximity in time, any other origin is
extremely unlikely), their Earth-crossing times would have been ~502 s
later than the Ulysses times given above.  Confirmation of the first
five events is being searched for in the data of other spacecraft.
(However, the BeppoSAX GRBM was not returning data for this period).
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