[vsnet-grb-info 1912] GRB050802: CrAO optical observations

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3744
SUBJECT: GRB050802: CrAO optical observations 
DATE:    05/08/03 11:02:17 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

E. Pavlenko, Yu. Efimov, A. Shlyapnikov, A. Baklanov(CrAO), A.Pozanenko
(IKI), M. Ibrahimov (MAO) on behalf of larger GRB follow up collaboration
report:

We observed the error box of   GRB050802 (Band et al., GCN 3734) with 2.6m
Shain telescope (CrAO) on August 2 between (UT) 18:46 - 20:40. OT found by
McGowan et al. (GCN 3739) is clearly detected. Preliminary VRI photometry is
following:

Mean time  Exposure Filter Magnitude
 (UT)        s

18:54       60       V      20.6
20:27      2x60      V      21.1
18:48       60       R      20.6
20:36      2x60      R      21.0
18:56       60       I      20.2
20:39      2x60      I      20.6

with a typical error of 0.1m.

Comparing decay index of fading light curve in V between magnitudes obtained
in UVOT observation (McGowan et al. GCN 3739) and our first observation in
18:54, and decay index obtained based on our observations we suggest that
the break of OT light curve occurs between (UT) 19:00 - 20:40. Detailed
analysis is underway.

Finding chart of the OT in V band can be found in
http://grb.rssi.ru/GRB050902.

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