GRB 030429

D. A. Smith on behalf of the ROTSE collaboration reports:

The ROTSE-IIIa telescope at Siding Spring Observatory, NSW, responded
automatically to the HETE ground alert 2695, beginning its first image less
than seven seconds after the alert time stamp, or 1.87 hours after the burst
trigger.  The automated burst response sequence consisted of ten 5-s, ten 20-s,
and forty 60-s images.  No sources not already in the USNO catalog were found
within 1.5 error radii of the SXC burst location.  Typical limiting magnitudes
for these images were 17.3, 18.2, and 18.7, respectively.  These magnitudes are
unfiltered and calibrated against the USNO A2.0 catalog R-band.  We co-added
the first five sets of ten frames to push the limiting magnitudes to 18.8,
19.5, and 19.9, respectively.  No candidate counterpart sources were found near
the error box.

K. Hurley, on behalf of the Ulysses GRB team,

E. Mazets and S. Golenetskii, on behalf of the Konus-Wind GRB team, and

T. Cline, on behalf of the Ulysses and Konus GRB teams, report:

Ulysses and Konus-Wind  observed this GRB at 24688 seconds.  As
observed by Ulysses, it had a duration of approximately 5 seconds, a
25-100 keV fluence of approximately  1.5E-06 erg/cm2, and a peak flux
of approximately  7.4E-07 erg/cm2 s over 0.25 seconds.

We have triangulated it to a preliminary annulus centered  at RA,
Decl(2000)= 332.879, -37.786 degrees, whose radius is 49.400 +/-  0.042
degrees (3 sigma ).

This annulus may be constrained and/or improved, but as the event was
not observed by Mars Odyssey, a small error box cannot be derived for
it.

A. Gilmore and P. Kilmartin (U. Canterbury) and
A. Henden (USRA/USNO) report:

We have imaged part of the error circle for
the HETE burst GRB030429 (HETE trigger 2695)
with the Mt. John 0.6m telescope (unfiltered, using
Rc zeropoint) and the USNOFS 1.55m telescope (Rc filter).
We find one fading object that may be the
optical counterpart to GRB030429.  This object does
not appear on the DSS-2 red plate.  Its position, along
with one comparison star from USNO-A2.0, is

OT     12:13:07.50  -20:54:49.7  J2000  (err: +/- 0.3arcsec)
Star A 12:13:01.05  -20:56:06.6  Rc=12.6

where coordinates are based on USNO-A2.0.  A 4x4arcmin
R-band finding chart can be found at
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb030429r.jpg
The candidate is about 7arcsec southwest of a 19th magnitude
star.  Photometry of the candidate with respect to Star A,
starting about 3.5hrs after the burst, yields:

   UTmid    CRmag   CRerr
Apr 29.591  19.34  0.11
Apr 29.600  19.43  0.13
Apr 29.616  19.71  0.16
Apr 29.660  19.87  0.19

It has faded more than another magnitude by May 01.25.
The color of the candidate is blue, but accurate colors
will be posted after calibration reductions are complete.

These observations were made as part of the AAVSO GRB
Network, and supported by a grant from the Curry Foundation.

Johan P. U. Fynbo (U. of Aarhus), Jens Hjorth (U. of Copenhagen), 
Sylvio Klose (TLS Tautenburg), Javier Gorosabel (IAA-CSIC/STScI), 
Andrew Levan (U. of Leicester), Nial Tanvir (U. of Hertfordshire), 
report on behalf of the GRACE collaboration:

"We have observed the field of GRB 030429 (=HETE trigger 2695) on two 
epochs with the ESO VLT. Using ISAAC on UT1 we have obtained Js and Ks
observations and with FORS2 on UT2 we have obtained V, R and I
observations. Our observations were carried out on April 29.94 and 
April 30.20 UT, i.e. 12.6 and 18.1 hours after the burst. We confirm 
the fading of the afterglow candidate proposed by Gilmore et al. 
(GCN 2184
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 ). Between our two epochs the source has faded by 0.43 
magnitudes in the V band. In our second epoch image the magnitudes of 
the source are about R=22 and Ks=17.9 implying a decay slope close to
1. The source is located 1.2 arcsec from an extended source NW of 
the afterglow position. This source has magnitudes of about R=24
and Ks=18.2. Our absolute photometry is based on preliminary zeropoints 
and is hence subject to considerable uncertainties. 

We note that the source is located 1.2 arcmin from the center of and
is hence formally outside the 90% SXC error-circle.

We acknowledge excellent support from the Paranal staff, in 
particular Cedric Ledoux, Rachel Johnson, Poshak Gandhi and Elena
Mason."

V.Rumyantsev (CrAO), A.Pozanenko (IKI) report:

We have imaged the error box of the HETE GRB030429 (HETE trigger 2695) with
AT-64 telescope of CrAO. Several unfiltered images with exposures of 120 s
were obtained in Apr. 29 between (UT) 18:19 and 20:57.  The OT found by
A.Gilmore at al. (GCN 2184
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 ) is marginally visible in co-added image. The
midtime of the co-added image (39x120 s) is Apr. 29.820. Due to short focal length 
of AT-64 (F=900mm, F/1.4)  the OT appears to be in the wing of the star

USNO A2.0  675-11945727
RA =12 13 07.92
DEC=-20 54 45.3
R=17.90  B=20.50

Star 1 in the image at
http://grb.rssi.ru/GRB030429/030429_030429_at64.gif

The limiting magnitude of the  image calibrated with USNO A2.0 catalog
R-band is 20.7, so we can estimate the OT magnitude as brighter as R=20.7m.
Our estimation is consistent with OT decay slope 2 which implies the
observation by  A.Gilmore at al. (GCN 2184
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 ).

Detailed calibration and PSF analysis is in a progress.

S. Nishiyama, D. Baba, T. Nagata (Nagoya U.), N. Matsunaga (U. of Tokyo),
and IRSF/SIRIUS team (Nagoya U., NAOJ), N. Kawai (Tokyo Tech), N. Tanvir
(U. of Hertfordshire) report:

We observed the SXC error box of GRB 030429 (HETE alert 2695) with the
Simultaneous three-color InfraRed Imager for Unbiased Survey (SIRIUS) on
the Nagoya-SAAO 1.4m telescope (IRSF).  For the afterglow candidate
proposed by Gilmore et al. (GCN 2184
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 ), we get the J H Ks magnitudes at 4
epochs begining 6.6 hrs after the burst:

   UTmid     J     H     Ks
Apr 29.727  18.8  17.8  17.0
Apr 29.873  19.2  18.3  17.5
Apr 30.005  18.9  18.1  17.4
----------------------------
Apr 30.768  19.0  18.4  17.8

We estimate the uncertainty in the magnitudes is about 0.2 mag. The Ks
magnitude seems to be consistent with that at April 30.20 reported by
Fynbo et al. (GCN 2185
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 ).  These observations confirm the fading
behaviour, but they were made under non-photometric conditions, and
the effect of the nearby NW source (GCN 2185
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 ) makes the photometry
less reliable, suggesting the results should be treated with caution.

This message may be cited.

Michael Weidinger, Johan P. U. Fynbo (U. of Aarhus), Jens Hjorth 
(U. of Copenhagen), Javier Gorosabel (IAA-CSIC/STScI), Paul Vreeswijk 
(ESO Chile), Sylvio Klose (TLS Tautenburg) report on behalf of the 
GRACE collaboration:

"We have observed the field of GRB 030429 (=HETE trigger 2695) around
May 2.2 UT with the ESO VLT. Using FORS1 on UT1 we have obtained a 
spectrum of the optical afterglow (GCN 2184
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 ) covering 3800 - 8000 
Angstrom. In the spectrum we identify a strong damped Ly-alpha line 
around 4442 Angstrom. This implies a lower limit of z=2.65 to the 
redshift of GRB 030429. The absence of Ly-alpha forest absorption on 
the red side of the line and the seemingly very large column density 
of the line renders a higher redshift very unlikely and we therefore 
conclude that z=2.65 is the redshift of GRB 030429. 

We acknowledge excellent support from Cedric Ledoux, Rachel Johnson, 
Poshak Gandhi and Elena Mason at the Paranal Observatory."

E. Berger (Caltech) and D. A. Frail (NRAO) report on behalf of a larger
collaboration:

"We observed the error circle of GRB 030429 (HETE trigger 2695) with the
VLA on 2003, May 2.10 UT at 8.46 GHz.  No sources are detected within the
error circle down to a 3-sigma limit of 0.18 mJy.  In particular, we do
not detect a radio source at the position of the optical counterpart
detected by Gilmore et al. (GCN 2184
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 )."

This message may be cited.

I. Khamitov (TUG), I.Bikmaev (KSU), M.Parmaksizoglu (TUG);
N. Sakhibullin, V. Suleymanov (KSU);
R. Burenin, R. Sunyaev, D. Denissenko, M. Pavlinsky, O. Terekhov, A.
Tkachenko, M.Gilfanov (IKI);
Z. Aslan, O.Golbasi (TUG);
U. Kiziloglu, A. Alpar, A. Baykal (METU);

report:

   We have observed the GRB 030429 optical afterglow (HETE trigger 
2695) with the 1.5-m Russian-Turkish Telescope RTT150 at TUG.

   A set of 10 exposures by 5 min. duration each  with Rc Bessell 
filter has been obtained on the night May 02/03, 2003, under good photometric 
conditions. Inspite of that TO was observered on large zenith distance, 
the seeing was stable and about 1.8 arcsec. We used TE Andor CCD with 
Marcony back-illuminated 2048 x 2048 chip (binned 2*2) cooled to -60C temperature.
   Aperture photometry was done according to Landolt stars observered 
at the same night.
   On combined (50 min) image there are two extended sources at the 
position of TO as noted in Fyndo at al. (GCN 2185
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 ). The brightness of the sources 
are close and Rc=23.5+/-0.5. Photometry was done without color term correction.
The bright source on about 7 arcsec northeast of TO is not a star-like 
source. Combined image and part of finding chart from Gilmore at al. (GCN 
2184
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 ) can be found at
http://www.tug.tubitak.gov.tr/gozlemler/GRB030429.jpg
 

This message may be cited.

J. Doty, R. Vanderspek, N. Butler, G. Crew, J. Villasenor, G. Monnelly,
T. Cline, J. G. Jernigan, A. Levine, F. Martel, E. Morgan, G.
Prigozhin, G. Azzibrouck, J. Braga, R. Manchanda, and G. Pizzichini, on
behalf of the HETE Operations and HETE Optical-SXC Teams;

Y. Shirasaki, C. Graziani, T. Donaghy, M. Matsuoka, M. Suzuki, T.
Tamagawa, K. Torii, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi,
T. Tavenner, Y. Nakagawa, D. Takahashi, R. Satoh, and Y. Urata, on
behalf of the HETE WXM Team;

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

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

write:

At 10:42:22.68 UTC (38542.68 s UT) on 29 April 2003, the HETE FREGATE,
WXM, and SXC instruments detected event H2695, a long GRB.

The burst triggered FREGATE in the 30-400 keV energy band.  No
real-time localization was sent to the GCN, since the weak fluence of
the burst in the WXM energy band resulted in a location that did not
meet the criteria for automatic propagation, and which was, in fact,
incorrect.

Ground analysis of the WXM data produced a localization that was
reported in a GCN Notice at 12:34:28 UT, 112 minutes after the burst.
The WXM ground localization SNR was 6.  The localization can be
expressed as a 90% confidence rectangle, whose center is at:

WXM-Ground: R.A. = 12h 13m 18s, Dec. = -20d 51' 09" (J2000),

and whose corners lie at:

R.A. =  12h 13m 32s, Dec. = -21d 01' 55"
R.A. =  12h 12m 50s, Dec. = -20d 59' 56"
R.A. =  12h 13m 03s, Dec. = -20d 40' 26"
R.A. =  12h 13m 46s, Dec. = -20d 42' 22" (J2000).

Ground analysis of the SXC data produced a localization that was
reported in the same GCN notice.  The SXC ground localization SNR was
6.  The localization can be expressed as a 90% confidence circle that
is 2 arcminutes in radius and is centered at:

R.A. = 12h 13m 06s, Dec. = -20d 56' 00" (J2000).

(The GCN Notice incorrectly reported the radius as 1 arcminute due to
operator error.)

The T_90 duration of the burst in the 30-400 keV band was > 14 s.

A light curve and skymap for GRB030429 is provided at the following
URL:

http://space.mit.edu/HETE/Bursts/GRB030429

I. Khamitov (TUG), I.Bikmaev (KSU), M.Parmaksizoglu (TUG);
N. Sakhibullin, V. Suleymanov (KSU);
R. Burenin, R. Sunyaev, D. Denissenko, M. Pavlinsky, O. Terekhov, A.
Tkachenko, M.Gilfanov (IKI);
Z. Aslan, O.Golbasi (TUG);
U. Kiziloglu, A. Alpar, A. Baykal (METU);

The correct reference in GCN 2208
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  is
Fynbo et al. (GCN 2185
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 ).

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

We have acquired BVRcIc all-sky photometry for
a 11x11 arcmin field centered about 3arcmin from the coordinates
of the optical transient (Gilmore et al. GCN 2184
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 )
for the HETE burst GRB030429 (H2695; Doty et al. GCN 2211
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 )
with the USNOFS 1.0-m telescope on two marginal nights.
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/grb030429.dat
The astrometry in this file is based on linear plate solutions
with respect to UCAC2.  The external errors are less than 100mas.
Due to the high airmass and drifting smoke from prescribed
forest fires, the external photometric error is larger
for B and Ic than normal; approximately 0.05mag.  We will
acquire additional photometry in the next week or so to
improve these errors.  We will also reposition to center
the optical transient.

As always, you should check the dates on the .dat file prior to
final publication to get the latest photometry.  There is
a README file on the ftp directory to give you information
about the procedures used to calibrate these fields.

Michael Weidinger, Johan P. U. Fynbo (U. of Aarhus), Jens Hjorth 
(U. of Copenhagen), Javier Gorosabel (IAA-CSIC/STScI), Sylvio Klose 
(TLS Tautenburg), Nial Tanvir (U. of Hertfordshire) report on behalf of the 
GRACE collaboration:

"Further analysis of the VLT spectra of the afterglow of GRB 030429 
(GCN 2184
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 ) and the neighbor galaxy at a separation of 1.2 arcsec from the 
afterglow (GCN 2185
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 , 2196
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 ) has led to the following conclusions. Based on 
absorption lines due to HI, OI, SiII, and CII we infer a redshift of 
z=2.6564+/-0.0008 for GRB 030429. Based on a single, weak emission line in 
the spectrum of the neighbor galaxy, which we interpret as [OII], and weak 
Calcium H and K absorption we infer a redshift of z=0.841+/-0.001 for the 
galaxy. This is consistent with the redshift of an absorption line in the 
spectrum of the afterglow if interpreted as MgII. This galaxy is therefore 
not the host galaxy of the GRB. In deep images obtained with the VLT/FORS2 
on May 5 the afterglow is only barely detected. We do not find any evidence 
for a host galaxy at the position of the afterglow to R>25. The separation 
between the position of the afterglow and the z=0.841 neighbor galaxy of 1.2 
arcsec is comparable to the Einstein radius for a massive galaxy at that 
redshift. Gravitational lensing could therefore affect the appearance of 
GRB 030429.

We acknowledge excellent support from the Paranal Observatory staff."

V.Rumyantsev (CrAO), V.Biryukov (SAI, MSU), A.Pozanenko (IKI) report:

We have performed PSF analysis of combined  image of the OT found by A.
Gilmore (GCN 2184
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 ). The unfiltered image was obtained on Apr. 29 between
(UT) 18:19 and 20:57 (GCN 2190
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 ). Based on field photometry (R-band) by
A.Henden (GCN 2214
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 ) we estimate brightness of the OT:

Mid.Time     exposure  mag (Unfiltered)
  (UT)         sec

Apr.29.820   39x120    20.20 +/-0.15

This brightness estimation is consistent with OT decay slope ~ 1 reported by
J.Fynbo (GCN 2185
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 ).

(We gratefully acknowledge the notion of J.Fynbo regarding the slope decay
reported in our GCN 2190
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 . Due to typo the slope decay was erroneously
calculated as 2)