GCN Circular 2011

GRB 030329: Optical pre-Imaging

C. Blake (Princeton) and J. S. Bloom (CfA) report:

"Using a signal-to-noise weighted stack of 50 NEAT images (taken from
1997-2002), we do not detect a counterpart at the position of the
transient afterglow of GRB 030329 (Price & Peterson; GCN #1985). The
images were acquired by R. Bambery, S. Pravdo, M. Hicks, and K. Lawrence
(Near-Earth Asteroid Tracking Project, Jet Propulsion Laboratory). We
therefore estimate the upper limit to the brightness of any host galaxy as
R=23.1 (2 sigma) or R=22.5 (3 sigma).  This result is consistent with the
somewhat more shallow limits reported in Wood-Vasey et al. (GCN #1998).
The absence of a host to such magnitude levels suggests a redshift of z >~
0.2, despite the extreme brightness of the early afterglow.

Within 7.5 arcseconds of the position of the OT, we find two sources
that are marginally detected (at the R=22.5 mag level):

------------------------------------------------------------------
      RA(J2000)       DEC                  Source-->OT
-------------------------------------------------------------------
 A: 10:44:49.776, +21:31:16.49    3.54" East, 1.66" North  d=3.91"
 B: 10:44:50.065  +21:31:10.77   -0.49" East, 7.38" North, d=7.40"

Positional errors relative to the USNO-B1.0 catalog are 0.5". These
sources are shown in an image linked from the webpage given below.
Photometric calibration of the stacked image was performed using the
USNO-B1.0 catalog. Some photometric secondary stars in the field are
listed below:

   RA(J2000)  DEC              R        B
		  	      mag      mag
-----------------------------------------------------
10:44:55.17 +21:28:11.3      17.69     18.48
10:44:43.40 +21:27:58.4      18.41     19.46
10:44:44.06 +21:27:18.5      18.52     20.47
10:44:53.61 +21:30:11.6      17.45     18.41
10:45:04.39 +21:29:56.1      18.22     20.37
10:44:55.67 +21:31:22.2      19.08     19.95
10:44:54.97 +21:31:42.7      18.51     20.36
10:44:48.68 +21:31:39.8      18.95     19.30
10:44:42.00 +21:32:31.7      15.08     18.18
10:44:50.44 +21:32:05.8      16.61     17.99
10:44:59.44 +21:31:43.9      18.07     19.84
-------------------------------------------------------

Finally, we note an object at (J2000) 10:44:55 +21:31:05.9, which
appeared in the DSS-II image, and is listed in the USNO-B1.0 as being
R=19.60, was detected at only R=21.9 in our stacked image."

A stacked image from NEAT that includes the WCS in the header may be
found at:
        http://astro.princeton.edu/~cblake/030329.html

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