TITLE:   GCN CIRCULAR
NUMBER:  2341
SUBJECT: GRB021206 optical counterpart upper limit
DATE:    03/08/04 07:44:56 GMT
FROM:    Vladimir Sokolov at SAO RAS  <sokolov@sao.ru>

T. Fatkhullin reports on behalf of the SAO RAS follow-up team:

The field of GRB021206 (GCN #1727, see also Coburn & Boggs 2003, Nature, 423,
415) was observed with 6 meter telescope of SAO RAS. The observations were
carried out with SCORPIO instument (see the Web-page
http://www.sao.ru/hq/moisav/scorpio/scorpio.html)
on 26 July 2003 during late evening twilight. The 15 1-min R-band exposures
were obtained starting from UT 26.7556 to 26.7896 July 2003. The field was
centered on the radio transient positions (Frail, GCN #2280). Astrometry of
the exposures sum was made using USNO A2.0 stars and errors obtained are
0.6 arcsec in R.A and Dec. Within the astrometry error circle at the position
of radio transient we did not detect any obvious optical source down to about
R=24.8 (3 sigma). But from about 2 arcsec to the North-West an extended dim
emission are observed. We should note that due to highlights from very bright
star on the image we caution about reality of this extended emission.
Photometric calibration was performed relatively to SExtractor (Bertin &
Arnouts 1996, A&AS, 117, 393) photometry of unsaturated USNO stars in our
field of  view. The sum of exposures can be seen at our anonymous FTP-site
ftp://ftp.sao.ru/pub2/grb/GRB021206/

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