GCN Circular 3547

H3800 and H3801 on 2005 June 11: two bursts from SGR1806-20 localized by HETE

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

C. Graziani, M. Arimoto, T. Donaghy, E. Fenimore, M. Galassi, J.
Kotoku, M. Maetou, M. Matsuoka, Y. Nakagawa, T. Sakamoto, R. Sato, Y.
Shirasaki, M. Suzuki, T. Tamagawa, K. Tanaka, Y. Yamamoto, and A.
Yoshida, on behalf of the HETE WXM Team;

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

N. Butler, G. Crew, J. Doty, R. Vanderspek, J. Villasenor, J. G.
Jernigan, A. Levine, G. Azzibrouck, J. Braga, R. Manchanda, and G.
Pizzichini, on behalf of the HETE Operations and HETE Optical-SXC
Teams;
 
report:

The HETE FREGATE, WXM, and SXC instruments detected and localized two
bursts from SGR1806-20 on 2005 June 11.

H3800 at 16:08:15 (58095 SOD) was an intense, intermediate burst
consisting of a single pulse with a rise time < 1 ms and a duration
~2.2 s.  The WXM flight localization can be expressed as a circle of
radius 14 arcminutes (90% confidence) that is centered at

WXM-flight: RA = 18h 08m 07s, Dec = -20d 18' 26" (J2000).

The first flight localization was distributed in a GCN Notice
issued at 16:23:57 UT. 

Ground analysis of the SXC data produced an 80" (90%) confidence
circle about RA = 18h 08m 39.2s, Dec =  -20d 24' 11.2",
i.e. consistent with SGR1806-20.

A preliminary spectral analysis indicates that this burst may
be fit over the 6 - 150 keV energy range by a two blackbody
model (Olive et al. Ap. J. 616, 1148, 2004) whose temperatures
are kT=4.6 and 10.3 keV.  The fluence over this energy range is
1.7E-05 erg cm^-2.  This burst was also observed by Konus-Wind
(GCN 3545
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 ) and RHESSI.

H3801 at 19:39:35 (70775 SOD) was a more typical short, weak burst
whose duration was <160 ms.  This burst was observed by FREGATE, the
WXM, and the SXC.  Ground analysis of the data produced a localization
that can be expressed as a circle of radius 12 arcminutes (90%
confidence) that is centered at

RA = 18h 08m 34s, Dec = -20d 20m 13s (J2000)

These two bursts, in addition to the two short-duration events H3784
(2005 June 02, 11031 SOD) and H3787 (2005 June 06, 39888 SOD) indicate
that SGR1806-20 remains active.  Further observations at all wavelengths
are encouraged.

This message may be cited.