TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4324
SUBJECT: HETE SXC localization of GRB 051211 (=H3979)
DATE:    05/12/11 07:17:57 GMT
FROM:    Carlo Graziani at U.Chicago  <carlo@oddjob.uchicago.edu>

J-L. Atteia, H. Clergeot, G. Ricker, N. Kawai, D. Lamb, and S. Woosley,
on behalf of the HETE Science Team;
 
M. Arimoto, T. Donaghy, E. Fenimore, M. Galassi, C. Graziani,
N. Ishikawa, A. Kobayashi, J. Kotoku, M. Maetou, M. Matsuoka,
Y. Nakagawa, T. Sakamoto, R. Sato, T. Shimokawabe, Y. Shirasaki,
S. Sugita, M. Suzuki, T. Tamagawa, K. Tanaka, and A. Yoshida, on behalf
of the HETE WXM Team;
 
N. Butler, G. Crew, J. Doty, G. Prigozhin, R. Vanderspek,
J. Villasenor, J. G. Jernigan, A. Levine, G. Azzibrouck, J. Braga,
R. Manchanda, G. Pizzichini, and S. Gunasekera, on behalf of the HETE
Operations and HETE Optical-SXC Teams;
 
M. Boer, J-F Olive, J-P Dezalay, and K. Hurley, on behalf of the HETE
FREGATE Team;
 
report:

At 02:50:05.4 UTC (10205.4 UT) on 11 December 2005 the HETE FREGATE, WXM,
and SXC instruments detected GRB 051211(=H3979), a GRB.

The flight location was distributed in a GCN Notice at 02:52:22 UTC. 
Ground analysis showed that the flight X-location derived from the X
detector is correct but that the Y-location derived from the Y detector
is unreliable, due to the low signal-to-noise of the burst in the Y
detector.  As a result, we believe that the flight location distributed
in the GCN Notice is incorrect.

Ground analysis of WXM data yields several possible Y locations.  One of
these locations corresponds to a location found through analysis of the
SXC data corresponding to much softer emission about 35s after the
trigger.  This may represent soft emission following the hard peak that
triggered HETE.  This SXC location was distributed in a GCN Notice at
05:58:30 UT.  The location is:

R.A. = 06h 56m 13s ; Dec. = 32d 40' 44" (J2000),

with a 90% confidence error radius of 80".

We caution that while this is our best estimate of the burst location,
under the circumstances we cannot be absolutely certain that this location
is correct.

Further analyses are in progress.  Further information about this burst
will be available at the following URL:

http://space.mit.edu/HETE/Bursts/GRB051211