GRB 051211

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

A. de Ugarte Postigo (IAA-CSIC Granada), S. Fernández-Acosta
(IAC Tenerife), S. Guziy, M. Jelínek, S. B. Pandey,
J. Gorosabel and A. J. Castro-Tirado (IAA-CSIC)

report:

"We have imaged a 7' x 7' region centred on the HETE-2/SXC
error box for GRB 051211 (Atteia et al. GCNC 4324) with the
0.8-m IAC telescope at the Observatorio del Teide starting
on Dec 11.279 UT (i.e. 3.9 hours after the GRB). Two frames
(600s exposure time, R-band) were taken under poor meteo-
rological conditions (strong wind and increasing background
due to the proximity of the twilight). No optical variable
is detected in a 3' field centred on the HETE-2/SXC error
box down to limiting magnitude of R about 19."

This message can be quoted.

G. Cusumano (INAF-IASF), D.N. Burrows, S. Hunsberger, C. Pagani (PSU), V. 
La Parola, and V. Mangano (INAF-IASF) report on behalf of the Swift XRT team:

The Swift XRT began observing HETE-discovered GRB 051211 (Atteia et al., 
GCN 4324
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 ) at 14:43:21 UT on 11 December 2005.  In the first two orbits we 
accumulated 3330 s of exposure time.  We find no X-ray counterpart within 
the HETE/SXC error circle, with a 3 sigma upper limit of 3.19E-3 
counts/s  (2.0 E-13 erg/s/cm/cm).  We note that this is considerably 
fainter than the typical Swift afterglow at this same time frame, though 
not inconsistent with the fainter Swift afterglows (Nousek et al. 2005, 
astroph/0508332).  Observations will be terminated at about 19:30 UT on 11 
December to prevent overheating of the XRT detector.

Klotz, A. (CESR-OMP), Boer M. (OHP), and Atteia, J.L. (LAT-OMP) report:

We imaged the entire field of GRB 051211 (H3979) detected by HETE-2
(Atteia et al. GCNC 4324) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France. Observations started 8.1
seconds after the GCN notice (and 3.14 hours after the GRB). The field
had an elevation of 33 degrees above horizon at the begining of the
observations and then decreased.

Two images of 90s were co-added. We compared the 3 arcmin field
centred on the HETE-2/SXC error box with stars of the USNO-B1
catalog. No new source appears brighter than R=15.3.

This message can be cited.