GRB 070429A

A. de Ugarte Postigo, A.J. Castro-Tirado, M. Jelinek,
P. Kubanek, R. Cunniffe, S. Vitek, J. Gorosabel (IAA-CSIC),
I. Skillen (ING) L. Sabau-Graziati (INTA) report:

Robotic observations from the  0.6m BOOTES-IR telescope
in R and z bands started at 3:50 UT (3.25 hours after the
burst), as soon as the object became visible from the
observatory. No source is detected inside the XRT error
box.

We have observed the field of GRB 070429A with
the 4.2m WHT+LIRIS in J, H and K bands starting at
05:44:00 UT (4.148 hours after the burst). Preliminary
reduction of the K-band data shows a faint source at the
following coordinates (J2000 +/- 1"):

R.A.: 19:50:48.90
Dec.: -32:24:17.0

A finding chart can be found at:
http://www.iaa.es/~deugarte/GRBs/070429A/GRB070429A.gif

Further analysis to check variability and colour of this
source is ongoing.

J. Cannizzo (GSFC/UMBC), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
 J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
 H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL),
 A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS),
 M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC)
 on behalf of the Swift-BAT team:
  
 Using the data set from T-239.0 to T+963.1 sec from the recent telemetry
 downlink, we report further analysis of BAT GRB 070429
 (trigger #277571)  (Barthelmy, et al., GCN Circ. 6355
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 ).  The BAT
 ground-calculated position is RA, Dec = 297.695, -32.420 deg which is
    RA(J2000) = 19h 50m 46.9s
    Dec(J2000) = -32d 25' 12.1"
 with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment). 
 The partial coding was 68%.
  
 The masked weighted light curve shows a single somewhat broad peak,
 extending out to T+50 sec, followed by several smaller peaks.
 T90 (15-350 keV) is 163 +- 5sec (estimated error including systematics).
  
 The time-averaged spectrum from T-12.4 to T+178.0 is best fit by
 a simple power-law model.  The power law index of the time-averaged
 spectrum is 2.11 +- 0.27. The fluence in the 15-150 keV band is
 9.2 +- 1.4 x 10-07 erg/cm2. The 1-sec peak photon flux measured
 from T+3.99 sec in the 15-150 keV band is 0.4 +- 0.2 ph/cm2/sec. 
 All the quoted errors are at the 90% confidence level.

R.L.C. Starling, A.P. Beardmore, K.L. Page, P.A. Evans (U. Leicester) and 
J. Cannizzo (GSFC/UMBC) report on behalf of the Swift XRT team:

We have analysed Swift XRT data from the first orbit of Windowed Timing
mode and two subsequent orbits in Photon Counting (PC) mode for GRB
070429A (trigger 277571, Barthelmy et al. GCN Circ 6355
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 ).

Using 380s of overlapping XRT PC mode data and UVOT V-band data, we
obtain an astrometrically corrected (using the USNO-B1 catalogue) X-ray
position of RA, Dec (J2000) = 297.70333, -32.40497, which is
RA(J2000) =   19h 50m 48.80s
Dec(J2000) = -32d 24' 17.9"
with an estimated uncertainty of 2.4 arcsec (90% error radius).
This is 1.0 arcsec from the XRT position in GCN 6355
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  and
1
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 .6 arcsec from the possible K-band optical transient report by
de Ugarte Postigo et al. (GCN Circ 6361
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 ).

The lightcurve is well fitted by a broken power law with
alpha1=6.4+0.3/-0.4, Tbreak=235+2/-20 s and alpha2=3.2+0.3/-0.2.

The PC mode spectrum can be fit with a single absorbed power law. The
photon index is 1.8+0.4/-0.2 and the
absorption is centred at 1.3E21 cm^-2 but is poorly constrained. The
Galactic column towards this position is 0.9E21 cm^-2.
The 0.3-10 keV flux is 1.25E-11 erg/cm^2/s, corresponding to 0.11
cts/s.

We are now in a data gap for this source, whilst Swift is
observing GRB 070429B, so the current decay rate
is not known, hence we do not give a predicted count rate for 24hr.
Further Swift observations of this source are planned.

This circular is an official product of the Swift XRT team.

P. Schady (MSSL/PSU) and J. Cannizzo (GSFC/UMBC) report on behalf of 
the Swift UVOT team:

Swift/UVOT observed the field of GRB 070429A starting 211s after the 
BAT trigger. No new source is detected either within the refined XRT 
position (GCN 6363
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 ) or at the position reported by Ugarte Postigo et 
al. (GCN 6361
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 ) in any of the UVOT filters, in either single or co-added 
exposures. The 3-sigma upper limits for the co-added exposures in each 
filter are as follows:

Filter        T_mid       Exp.     Mag 3-sig UL
                      (s)           (s)
White       850          253      19.43
V               1104       903      19.75
B               1700       107      19.30
U               1598       117      18.96
UVW1      3535        259     19.19
UVM2       3951       333     19.61
UVW2      1659        117     19.07

where T_mid is the weighted mid time of the co-added images. The 
reported upper limits are uncorrected for the estimated Galactic 
reddening of E(B-V) = 0.17 mag.

P.A. Price (IfA, Hawaii) reports on behalf of a larger collaboration:

We observed the XRT position of GRB 070429A (GCN ##6355,6363) with the
Gemini North telescope + GMOS, commencing at 2007 Apr 29.58 UT (12.3
hours after the GRB).  Observations consisted of 2x180 sec integrations
in Sloan i' and 4x180 sec in Sloan z'.

The source identified by de Ugarte Postigo et al. (GCN #6361
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 ) is well
detected in these observations, though no statement as to its
variability can yet be made.  In addition, there is a fainter source
within the XRT error circle, at coordinates:

	19:50:48.77 -32:24:17.8 J2000

NIR imaging of this GRB has also been made, and will be reduced as
practical.  No further observations are planned.

We thank the Gemini North staff for helpful support of these quick
response observations.

R.L.C. Starling, P.A. Evans, K.L. Page and A. Beardmore (U. Leicester)
report on behalf of the Swift XRT team:

We have further analysed the Swift XRT data for GRB 070429A (Barthelmy 
et al., GCN Circ. 6355
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 ) out to 290 ks since the BAT trigger. 
The steep lightcurve decay reported in GCN Circ. 6363
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  has broken at 
T+1100 s to a slope of alpha~0.37. This plateau phase continues through 
the observations to date, out to about T0+290 ks, with a current count
rate of
~0.006 count/s corresponding to a flux of 1.8e-12 erg/cm^-2/s. Probable
X-ray flaring activity is seen during this phase.

The duration of the plateau phase is longer than that normally observed
in GRBs showing a similar phase (e.g. Nousek et al. 2006; O'Brien et al.
2006),
hence the source remains X-ray bright. 
Continuation of optical and infrared observations of GRB 070429A is
therefore
strongly encouraged. 

This circular is an official product of the Swift XRT team.