TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3939
SUBJECT: GRB050904: CrAO optical observations
DATE:    05/09/07 21:38:18 GMT
FROM:    Vasilij Rumjantsev at CrAO  <rum@crao.crimea.ua>

V.Rumyantsev (CrAO), V.Biryukov (SAI, MSU), A.Pozanenko
(IKI), M. Ibrahimov (MAO) on behalf of larger GRB follow up
collaboration report:

We observed the BAT and XRT   error boxes of GRB050904
(Swift # 153514; Cummings et al., GCN 3910) with 2.6m Shain
telescope (CrAO) on September 4 between (UT) 20:39 - 21:31
in R-band filter. The OT (Haislip et al., GCN 3913, D'Avanzo
et al. GCN 3921) is not detected in our combine image.
Preliminary estimation of  the limiting value of the
combined image based on USNO-A2.0 catalog is following

Mean time  Exposure Filter Magnitude
 (UT)        s

21:04      24x120    R      23.5

Combined image can be found in http://grb.rssi.ru/GRB050904.

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