GRB 011212

GRB011212 (=XRF011212) (=H10001): An X-ray Flash/X-ray Rich GRB Detected by
HETE

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

N. Butler, G. Crew, J. Doty, G. Monnelly, G. Prigozhin, R. Vanderspek,
J. Villasenor, T. Cline, J.G. Jernigan, A. Levine, F. Martel,
E. Morgan, J. Braga, R. Manchanda, and G. Pizzichini, 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, T. Tavenner,
C. Graziani, and T. Donaghy, 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:

The HETE Fregate and WXM instruments have detected and localized a
burst at 14642.00 SOD {04:04:02.00} UT on 12 December.  The burst was
an untriggered event, and appears to be an X-ray rich GRB with a
duration of > 80 seconds.

In the Fregate 8-85 keV band, the statistical significance was 9.8
sigma. A total of 3724 counts were detected during that interval,
corresponding to a fluence of ~6.7 x 10-7 cm-2. The peak flux was
~1.8 x 10-8 ergs cm-2 s-1 (i.e., ~0.5 x Crab flux), assuming a
Crab-like spectrum. In the WXM 2-25 keV band, the statistical
significance was 6.9 sigma.

Based on the WXM data, the best fit location for GRB011019 is:

RA = 05h00m05s, Dec = +32o07'39"

with a total error radius of 11 arcminutes (90% confidence region).

The duration in the WXM 2-10 keV band was > 80 s. A total of ~3500
counts were detected during that interval.

Further refinement of the burst localization is in progress.

This message is quotable.

D.W. Fox and P.A. Price (Caltech) with S. Pravdo, E. Helin, K. Lawrence 
and M. Hicks (NEAT/Palomar) report on behalf of the larger
Caltech-NRAO-CARA GRB collaboration:

"We have observed the error box of the HETE GRB011212 (GCN #1194
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 ) with
the Palomar 48-inch telescope on 2001 December 13.15 UT.  Our 120s
exposure covers the entire HETE + RXTE/ASM joint error box to
approximately the DPOSS plate limit (r ~ 21 mag).  We detect only one
bright object not present on the DPOSS F-plate, which object we
identify as an asteroid based on its large proper motion on comparison
with an image taken 20 minutes later.  No other afterglow candidates
are identified within the error-circle.  Further observations are
planned."

This message may be cited.

A. Henden (USRA/USNO) reports on behalf of the USNO GRB team:

We have acquired BVRcIc all-sky photometry for
an 11x11 arcmin field that is approximately centered on
the joint HETE/RXTE_ASM error box for GRB011212 (GCN 1194
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 +alert)
with the USNOFS 1.0-m telescope on one photometric
(but poor seeing) night.  Stars brighter than
V=13.5 are saturated and should be used with care.
We have placed the photometric data on our anonymous ftp site:
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb011212.dat
The current photometry has a potential external zero-point
error of about two percent.  The astrometry in this file
is based on linear plate solutions with respect to USNO-A2.0.
The internal errors are less than 100mas.

Further calibration of this field will be performed if
an optical transient is discovered.

Here is a report of the optical observation of the field of GRB 011212:

GRB 011212: optical observation at Oslo

O. Trondal, Oslo, Norway, and H. Yamaoka, Kyushu Univ., report on
behalf of VSNET-GRB collaboration:

"The field of GRB 011212 (=H10001, GCN 1194
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 , 1196
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 ) is observed by O.
Trondal with 0.25-m F/4.2 telescope and CCD on Dec. 12.813 - 12.924
UT, i.e. 0.64 - 0.75 days after the burst.  The image almost coveres
the joint HETE/RXTE_ASM error box except a small Decl. > +32o17'00"
region.  The limiting magnitude of the combined (25 times 5 minutes)
image is rmag about 18.5.  We detect no afterglow candidate in the
error box."

Sincerely Yours,
Hitoshi Yamaoka, Kyushu Univ., Japan
yamaoka@rc.kyushu-u.ac.jp

P.Saracco,S.Covino,G.Ghisellini,D.Fugazza (AO Brera),
N.Masetti,E.Palazzi(ITeSRe, CNR, Bologna), E.Pian (OA Trieste),
A.Antonelli,F.Fiore,G.L.Israel,L.Stella (OA Roma),
S.Desidera (OA Asiago),
on behalf of a larger collaboration, report:

We have acquired  1800s exposure(2 images, 900s each)
in the R-band of the ~8x8 arcmin field centered on the
error box  of the HETE GRB011212 (GCN #1194
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 ).
Observations have been carried out  on December 13.15
UT at the Mt. Ekar 1.8 m telescope under no good seeing
conditions, the measured FWHM being ~3 arcsec.
The nominal limiting magnitude reached in the combined
image is R~22.7 (5 sigmas within 3 arcsec aperture).
We  do not detect any object not present in the DSS plate,
with the exception of the asteroid previously quoted in
GCN #1196
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 .

This message may be cited

A.V. Sergeev, V.B.Petkov, V.Ya.Poddubny, N.V.Karpov, S.N.Karpov.
Centre  Astronomical and Medico-Ecological Researches of Academy of Sci.
Observatory at peak Terskol, Russia. 
 
 	We have observed the 8x9 arcmin box of the HETE GRB011212 
(GCN #1194
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 ) with the 2-m telescope of peak Terskol observatory  on
2001 December 12.85 UT. Our 4x300s  exposure were centered on coordinates
RA=05h00m05s   Dec = +32o07'39" . 
  The limiting magnitude of the image is Rmag about 21.5.  
 Visual comparison of the images with the DSS reveals   no other obvious
new objects, to a limiting magnitude of roughly R~19.5."

Further observations are planned.

This message may be cited.

-----------------------------------------------------------------------
Centre  Astronomical and Medico-Ecological Researches of Academy of Sci.
Observatory at peak Terskol, Russia.   terskol@burbonz.nalnet.ru
-----------------------------------------------------------------------
 
[GCN OPS NOTE:  This message was received at 09:02 UT, but it was not 
distributed because it was emailed to my personal account instead 
of the gcncirc account.]

K. Kinugasa, O. Hashimoto (Gunma Astronomical Observatory), E. Kambe
(National Defense Academy), Y. Urata, M. Kohama, K. Torii, N. Kawai,
A. Yoshida (RIKEN), and H. Yamaoka (Kyushu Univ.)
 
 We observed the central part of the error region of GRB011212 (GCN
#1194
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 ) with the Gunma Astronomical Observatory's 150-cm telescope.
Starting at 2001 December 12.547 UT, five 120-s exposures were made
(last two were affected by a cloud) in R band at a square region
within the four corners of (R.A., Dec.) = (04:59:35.5, +32:03:19),
(04:59:43.6, +32:13:52), (05:00:33.4, +32:12:09), and (05:00:25.3,
+32:01:36) (J2000). Five 120-s exposures were made at the same
position from 2001 December 13.545 UT as well as other two fields,
which covered the entire HETE + RXTE/ASM joint error region except for
a small southernmost part (Decl. < +31:57:20). Combined images of each
pointing were as deep as DPOSS plate limit. Comparison with the DPOSS
image did not show an optical afterglow candidate brighter than 20.5R
mag.

F.J. Vrba (USNO), A.A. Henden (USNO/USRA), and B. Canzian (USNO)
report on behalf of the USNO GRB team:

We used the USNO 1.3-m telescope to obtain Ic-band imaging at two
epochs of a 20(N-S)x40(E-W) arcmin field that is approximately centered 
on the joint HETE/RXTE_ASM error box for GRB011212 (GCN 1194
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 +alert).
The registration covers approximately 95% of the error box, with only
4 arcmin in declination of its southern tip missed. Observations
on both nights consisted of six 10 minute integrations using a Site
2Kx4K CCD and were calibrated photometrically using several stars
in the field from Henden (GCN 1198
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 ). Observations were obtained on
UT 2001 Dec 13.294-13.351 (1.125-1.182 days after the burst) with
the combined frames reaching a limiting magnitude of Ic < 21.6 and 
on UT 2001 Dec 14.207-14.281 (2.038-2.112 days after the burst) 
reaching a limiting magnitude of Ic < 21.9 (due to better seeing than 
on the previous night). The combined frames from each night were
blinked and the entire 20x40 arcmin FOV was searched with the result 
that no fading objects were found. 

The GRB position (at l ~ 172 deg, b ~ -6 deg) is a region of
moderately high Galactic extinction, with E(B-V) ranging from 0.71 to
0.84 at the center and corners of the error box based on the dust maps
of Schlegel et al. (ApJ, 500, 525). Assuming a normal extinction law,
this implies a range of A_I of about 1.4-1.6 mag. Our observations
thus place an apparent upper limit of Ic > 21.6 or an extinction-corrected 
limit of Ic > 20.0-20.2 at 1.125-1.182 days after the burst for an
Ic-band counterpart to GRB011212.

These results may be cited.

GRB011212: Optical Observations

A. Dullighan, G. Monnelly, G. Ricker, R. Vanderspek, N. Morgan (MIT);
and D. Tholen (U.Hawaii)

write:

We have observed the error box of the HETE GRB011212 (GCN #1194
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 ) with
the Baade 6.5m telescope at Magellan on 2001 December 14.17 UT (Epoch
1) and December 15.17 UT (Epoch 2) using the MagIC CCD detector.
Twelve 360s R-band exposures were used to mosaic the entire HETE and
RXTE/ASM joint error box on each night.  Both nights had a seeing of
0.7" with a limiting magnitude of 24.5, except for the last half of
the second night when the seeing decreased slowly to 1.3", with a
limiting magnitude of 24.0 on the last frame.  Third epoch
observations were made with the University of Hawaii 2.2m telescope on
Mauna Kea on 2002 February 16.33 and 17.38 UT.  Three frames were used
to mosaic the error box each with three 600s VR-band exposures under
conditions of 1.3" seeing, giving a limiting magnitude of 24.5 after
summing.

Aperture photometry was performed on all objects detected in the
Epoch 1 images and then again at the same positions in the later
epochs.  The absolute magnitude of each source was calculated using a
nearby USNO catalog star: for each source, the same calibration star
was used in all epochs, and the quoted error in the magnitude does not
include the uncertainty in the magnitude of the calibration star.
Comparison with Epoch 3 is complicated by the fact that it is in
VR-band, whereas Epochs 1 and 2 are in R-band.  Four sources were
determined to have faded between both Epochs 1 and 2 and between
Epochs 1 and 3.  Their positions and magnitudes are listed below.
Sources 2, 3, and 4 faded to near the detection limit in Epoch 2, and
to below the detection limit in Epoch 3.  The observed fading and
upper limits are consistent with a temporal power law decay index
between -1 and -2, except for source 1 in Epoch 3, but this flattening
of the decay could be due to an underlying galaxy.

grb event: 2001 December 12.1695 UT
Epoch 1:   2001 December 14.17	2.0 days after
Epoch 2:   2001 December 15.17 	3.0 days
Epoch 3:   2002 February 16.33 	66.2 days
            2002 February 17.38 	67.2 days

Fading Sources
     RA       Dec        Epoch 1 m(R)    Epoch 2 m(R)     Epoch 3 m(VR)
1  4:59:58.1 +32:02:57  23.14 +/- 0.12  23.89 +/- 0.22   24.08 +/-0.24
2  4:59:59.4 +32:03:43  23.80 +/- 0.18  24.65 +/- 0.39    > 24.5
3  4:59:59.0 +32:09:04  23.75 +/- 0.18  24.80 +/- 0.48    > 24.5
4  4:59:39.5 +32:08:34  23.38 +/- 0.12  24.41 +/- 0.38    > 24.5

Finder charts have been prepared of the four sources from the Epoch 1
observations at http://space.mit.edu/HETE/Bursts/GRB011212.  The
charts contain the source, marked by crosshairs, a bright star (B)
from the USNO catalogue, and a constant star (C) of comparible
magnitude to the source.  The charts have a width and height of 33
arcseconds in RA and Dec.  North is up and East is to the left.

Source#    m(R)               Star B m(R)	 Star C m(R)
  1         23.14 +/- 0.12     18.8(USNO)	 23.65 +/- 0.15
  2         23.80 +/- 0.18     16.9(USNO)	 23.59 +/- 0.15
  3         23.75 +/- 0.18     14.4(USNO)	 23.48 +/- 0.14
  4         23.38 +/- 0.12     16.8(USNO)	 23.11 +/- 0.09


  This message may be cited.