GRB 050209

K. Torii (Osaka U.) reports:

 The entire error region of GRB050209 (HETE trigger #11568) was
observed with 0.3-m remote telescope in the New Mexico Skies
Observatory. The imaging started at 03:57 UT and 120-s exposures in
I-band was repeated.
 As a result of the preliminary analysis, we do not identify a new
object brighter than 17 mag (120s x 5 frames, USNO-A2.0 R magnitude).

===

GRB050209 (=U11568):  A Long GRB Detected by HETE

N. Kawai, G. Ricker, J-L. Atteia, D. Lamb, and S. Woosley, on behalf 
of the HETE Science Team;

T. Donaghy, E. Fenimore, M. Galassi, C. Graziani, M. Matsuoka, Y. 
Nakagawa, T. Sakamoto, R. Sato, Y. Shirasaki, M. Suzuki, T. Tamagawa, 
Y. Urata, T. Yamazaki, Y. Yamamoto, 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, and G. Pizzichini, 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 that:

Post-processing analysis of HETE data has revealed the presence of 
GRB 050209, an untriggered GRB (=U11568) detected as HETE was 
entering the SAA. The burst was detected at 01:31:41 UT and had a 
duration of approximately 40 seconds.  The GRB has been localized to 
a circle of radius 7' (90% confidence) centered at:

RA = 08h 26m 09s, DEC = +19d 41m 02s (J2000).

Light curves in four spectral bands and a skymap for GRB 050209 are
provided at the following URL:

http://space.mit.edu/HETE/Bursts/GRB050209

Because of the proximity of the SAA, extraction of spectral data 
requires manual processing, and will be provided in a follow-up GCN 
Circular.

This message may be cited.

S. Bradley Cenko and Derek B. Fox report on behalf of the
Caltech-NRAO-Carnegie GRB collaboration:

We have imaged the full error circle of GRB050209 (HETE 11568, GCN 3013
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 )
with the automated Palomar 60-inch telescope.  Observations commenced
approximately 6 minutes after receiving the HETE trigger.  We have
obtained two epochs of coverage in the Kron R filter at median epochs of
approximately 4:15 UT (2.7 hours after the burst) and 6:00 UT (4.5 hours
after the burst).

In the first epoch, we find no new source by comparison with the Digitized
Sky Survey to a limiting magnitude of R ~ 20.5 (magnitudes calculated
with reference to the Guide Star Catalog).  Visual comparison between
our two epoch shows no sign of any fading sources in the field.

We also note the presence of a minor planet, 1998 WB7, about to enter the
HETE error circle at the time of our second epoch.

Further observations are planned.

G.Bourban, C.Vuissoz, F.Carrier, G.Burki and L.Weber (Geneva 
Observatory, Switzerland) report:


We have carried out optical observations of the 12'x 12' field centered 
on the error circle of HETE trigger #11568 (~93% of the whole 
uncertainty area provided by HETE/WXM) using the C2 CCD Camera mounted 
on the Swiss 1.2-meter telescope located at the ESO La Silla Observatory 
(Chile). The observations began on 2005 Feb 09 at 03:57:30 UT (129s 
after the alert sent by HETE team, i.e 2.43 h after the burst) and four 
different sets of measurements were performed during the night at 03:57 
UT, 04:57 UT, 06:07 UT and 07:12 UT (1.5 < Fz < 2.7). A total of 3 
R-filtered images with exposure time of 180s as well as 8 R-filtered 
480s exposures were obtained under good wheather conditions.

The division of these images as well as their comparison with the 
USNO-A2 catalog did not reveal any new or fainting source inside the 
field of view of the C2 camera, down to a limiting magnitude of R < 20.5.

This message may be cited.

Y. Yatsu, M. Arimoto and N. Kawai (Tokyo Tech) report on behalf of 
MITSUME collaboration, 

"We observed the field covering the entire error circle of GRB050209
(GCN 3013
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 , Kawai et al.) with the 50 cm Mitsume Telescope at Akeno,
Japan in I band starting at 10:07 UT for 25 min.

Co-adding 49 frames of 30 sec exposure, we detected no new objects
down to a limiting magnitude of I=18.6."

P. D'Avanzo, A. Melandri, S. Covino, E. Palazzi,  V. Testa, F.  
D'Alessio, D. Malesani, L. A. Antonelli, F.M. Zerbi, G. Tosti, A.  
Monfardini, L. Nicastro, G. Chincarini, M. Rodono', G. Cutispoto, E.  
Molinari, F. Vitali, on behalf of the REM/ROSS Team report:

"We imaged the field of GRB050209 (HETE 11568: Kawai et al, GCN 3013
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 )  
with the robotic 60cm REM telescope located in La Silla (Chile)  
starting observations 24 seconds just after received the trigger  
through GCN Notice.

Observations were performed in fully automated mode with the REM  
Optical Slitless Spectrograph (ROSS) in the V, R and I filters (REM IR  
camera was in manteinance). Oservation started on 2005 Feb 09.163 UT,  
approximately 2.4 h after the GRB. The field was imaged in each filter  
for a total exposure time of 400s, under good seeing conditions.

No new sources are detected within the HETE error circle by comparison  
with the Digitized Sky Survey, down to a limiting magnitude V=19.1,  
R=19.1, I=18.5 (5-sigma confidence).

This message is citeable."

GRB 050209(=U11568):  Duration and spectrum

D. Lamb, G. Ricker, J-L. Atteia, N. Kawai, and S. Woosley, on behalf of
the HETE Science Team;

T. Donaghy, E. Fenimore, M. Galassi, C. Graziani, M. Matsuoka,
Y. Nakagawa, T. Sakamoto, R. Sato, Y. Shirasaki, M. Suzuki,
T. Tamagawa, Y. Urata, T. Yamazaki, Y. Yamamoto, 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, and G. Pizzichini, 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:

The T_50 durations for GRB 050209 are approximately 16, 17, and 15 s in
the 6-40, 6-80 and 30-400 keV energy bands, respectively; the T_90 
durations for the burst are approximately 36, 41, and 46 s in the same
energy bands.

The spectrum of GRB 050209 evolves strongly from hard to soft during
the burst.  Ground analysis of the FREGATE and WXM spectral data show
that the average spectrum of the burst is adequately fit by a single
power-law with index alpha = - 1.7 � 0.07 in the 2-400 keV energy band,
implying that E_0 lies near or above 400 keV and E_peak lies above 120
keV.  The fluences in the 2-30 keV and 30-400 keV energy bands are 1 x
10-6 and 2 x 10-6 erg cm-2, respectively; the fluence in the 2-400 keV
energy band is therefore 3 x 10-6 erg cm-2.  The fluence ratio 
S(2-30 keV)/S(30-400 kev) = 0.33.  Technically, this makes GRB 050209 
an "X-ray rich" burst, despite the relatively high value of E_peak.  
This is due to the steepness of the low-energy power-law index alpha. 
Because we are only able to place a lower bound on E_peak, we can only
place a lower limit on the pseudo-redshift for this burst of about 2.

A light curve, skymap, and some spectral information for GRB 050209 are
provided at the following URL:

http://space.mit.edu/HETE/Bursts/GRB050209

This message may be cited.

Alain Klotz (CESR-OHP), and Michel Boer, (OHP) on behalf of the TAROT team
report:

"We imaged the entire field of GRB 050209 with the TAROT robotic telescope
located at the Calern observatory, France. Observations started 26 seconds
after the receipt of the GCN notice, i.e. approx. 2h25 after the event. The
position was at an elevation of 22 degrees above the western horizon. No new
source was detected after a comparison with the USNO A2-0 catalogue. From a
frame to frame study no decaying source was found. We co-added 84 30s
images: we reach a limiting R magnitude of 19.2. 

A summary of the data, as well as TAROT images can be found at the following
URL: http://www.cesr.fr/~klotz/grb050209/ "

This message is citable.