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THE ASTRONOMER Electronic Circular No 2382      2007 Oct 04 14.32UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise,  Basingstoke,
Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074
INTERNET: GUY@TAHQ.DEMON.CO.UK      Backup: gmh@wdcc1.bnsc.rl.ac.uk
WORLD WIDE WEB                         http://www.theastronomer.org
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GRB 071003: OA RE-BRIGHTENING AS SUPERNOVA?
H. Swan, University of Michigan et. al. report on GCN 6841 that the 
optical counterpart of GRB 071003 (cf TA E-Circular 2381) was recorded 
by the AEOS Burst Camera (ABC) on the AEOS telescope, located at the 
Maui Space Surveillance System on Haleakala. The
images are unfiltered 10s exposures which started ~9 minutes after the 
trigger and ended ~ 3 hours later.
They detect the OT first identified by W. Li (GCN 6838). A preliminary 
analysis gives a magnitude of approximately 16.04+/-0.01 at 7:40:55 UT.

W. Li on behalf of the KAIT GRB team report on GCN 6844 analysis of KAIT 
observations with selected KAIT unfiltered photometry:
t_start(s)     Exptime(s)     Mag     Mag(err)
  42            5.000        12.83   0.02
  67            5.000        13.56   0.03
249           20.000        14.82   0.03
431           20.000        15.89   0.06

C.Y. Shih, EAFON team reports on GCN 6846 details of R-band observations 
using Lulin 1-m telescope at 11:41:44 UT (about 4 hours after the 
burst). There is no optical afterglow emission
in their combined image with R<21.5 (3-sigma limit) derived from 
USNO-B1.0 red stars.

D.A.Perley et.al., University of Berkeley, relays on GCN 6847 that on 
the night of 2007-10-04 (UT) they imaged the field of GRB 071003 with 
Keck I + LRIS, in g+R filters simultaneously for 3 exposures of 300 
seconds, starting at 04:49 UT.
They detect at the position reported a bright source with an estimated 
magnitude of R~20, though photometry is complicated by the presence of 
the nearby 11th magnitude star.  The position is consistent within 0.3" 
of the KAIT detection, strongly suggesting that this is the same source. 
Given the rapid fading noted in earlier circulars and the limit of R > 
21 reported by Shih et al. this may suggest that the optical afterglow 
is re-brightening, either due to a late-time flare or a rising 
low-redshift supernova.
We also note what appears to be a faint, extended object approximately 
2" to the southwest of the afterglow (towards the bright star), which 
may be the host galaxy of this burst.

In response to TA E-Circular 2381, Peter Birtwhistle, Great Shefford, 
England reports that a stack of 29 x 10 second exposures (averaged 
rather than added together) taken on Oct 3, from 19:29:49 to 19:36:49 
shows only a hint of non-uniformity in the brightness at the object's 
position, the brightness of the pixel at the position indicated from 
E2381 is equivalent to the brightest pixel of a star of about mag +17.3 
R, but that is probably a negative upper limit rather than a detection.

Brendan Shaw and Dave Shave-Wall of Basingstoke, England report negative 
results on the evening of October 3 using a 0.40-m Schmidt-Cassegrain 
telescope.

Editor: Given the possibility of a re-brightening and subsequent 
supernova counterpart observers are encouraged to re-image the field at 
the earliest opportunity.

Guy M Hurst