TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  1070
SUBJECT: SGR1806-20: A Second, Intense Burst Localized by HETE
DATE:    01/06/23 18:21:44 GMT
FROM:    George Ricker at MIT  <grr@space.mit.edu>

SGR1806-20: A Second, Intense Burst Localized by HETE

G. Ricker, D. Lamb, and S. Woosley on behalf of the HETE Science Team;

R. Vanderspek, G. Crew, J. Doty, G. Monnelly, J. Villasenor; N. 
Butler, T. Cline, J.G. Jernigan, A. Levine, F. Martel, E. Morgan, G. 
Pizzichini, and G. Prigozhin, on behalf of the HETE Operations and 
HETE Optical-SXC Teams;

N. Kawai, M. Matsuoka, Y. Shirasaki, T. Tamagawa, K.Torii, T. 
Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, and  C. Graziani, on 
behalf of the HETE WXM Team;

J-L Atteia, M. Boer, J-F Olive, J-P Dezalay, and K. Hurley on behalf 
of the HETE FREGATE Team;

write:

At 15:54:53.123 UT on 23 June, the HETE FREGATE and WXM instruments 
detected and localized an intense burst from SGR1806-20, a soft 
gamma-ray repeater. This event, disseminated in near real time as a 
GCN Alert (HETE BID_1566; see 
http://gcn.gsfc.nasa.gov/gcn/hete_grbs.html), is the second burst 
localized from this source in the past week. (The first burst was 
reported in GCN Circular #1068). The coordinates (J2000) of the 23 
June burst are:

R.A. = 272.1460 deg. (18h08m35s.02)

Dec. = -20.3658 deg. (-20:21:56)

The error circle for this localization is 6 arcmin in radius. 
SGR1806-20 lies 3.1 arcmin from the HETE position.

The burst duration in the 8-40 keV band was ~200 ms, comprised of two 
peaks each <100ms in duration. A total of 2250 counts were detected 
during that interval, corresponding to a fluence of ~4 x 10-7 ergs 
cm-2 . The peak flux was >6 x 10-6 ergs cm-2 s (ie >200 x Crab flux).

Follow-up observations of this transient are encouraged.

Additional information on this burst detection (including light 
curves), as well as for the HETE mission, will be available at:

http://space.mit.edu/HETE/

Acronyms: HETE=High Energy Transient Explorer
FREGATE=French Gamma Ray Telescope
WXM=Wide Field X-ray Monitor
SXC=Soft X-ray Camera

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