[vsnet-grb-info 8526] GRB 091018: ROTSE-III Detection of Optical Counterpart
GCN Circulars
gcncirc at capella.gsfc.nasa.gov
Mon Oct 19 06:34:38 JST 2009
TITLE: GCN CIRCULAR
NUMBER: 10036
SUBJECT: GRB 091018: ROTSE-III Detection of Optical Counterpart
DATE: 09/10/18 21:34:32 GMT
FROM: Brad Schaefer at LSU <schaefer at grb.phys.lsu.edu>
B. E. Schaefer (Louisiana State) and S. B. Pandey (U Mich), report on
behalf of the ROTSE collaboration:
ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia,
responded to GRB 091018 (Swift trigger 373172, Stamatikos et al., GCN
10034). The first image was at 20:57:36.1 UT, 556.6 s after the burst
(11.1 s after the GCN notice time). The unfiltered images are calibrated
relative to USNO A2.0. We detect a new object, not visible in the DSS
(second epoch), with coordinates:
02:08:44.6 -57:32:53.6 (J2000),
with positional uncertainty of 1" or better
start UT mag mlim(of image)
----------------------------------
20:57:36.1 15.4 16.4
With this, we confirm the optical afterglow reported in GCN 10034 as a
UVOT detection. The source is rapidly fading. A jpeg image is available
at
http://www.rotse.net/images/gsb373172_3c01_img.jpg Note that the object
numbered 14 (in the lower of the two circles) is the candidate in
question.
Continuing observations are in progress.
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