[vsnet-grb-info 1924] GRB 050803: RTT150 optical observations

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3763
SUBJECT: GRB 050803: RTT150 optical observations
DATE:    05/08/04 20:24:56 GMT
FROM:    Rodion Burenin at IKI, Moscow  <rodion at hea.iki.rssi.ru>

R. Burenin, A. Tkachenko, M. Pavlinsky, R. Sunyaev (IKI), 
I. Khamitov, Z. Aslan (TUG), U. Kiziloglu (METU), A. Alpar (SabUni),
I. Bikmaev, N. Sakhibullin (KSU/AST)

report:

We observed error box of GRB 050803 (GCN 3748) with Russian-Turkish
1.5-m telescope (RTT150, Bakyrlytepe, TUBITAK National Observatory,
Turkey). The observations were started at 20:00 UT, i.e. 0.77 hours
after the burst. We observed the field till the dawn, which occurs at
2:00 UT, Aug 4.

We made a set of 30--60s exposures in R. At the position of X-ray
afterglow we found the object mentioned in GCN 3753, as well as one
other fainter object at the edge of XRT error box, probably one of those
mentioned in GCN 3758.

The first object is definitely extended. It have R=~22.2 and is stable
within ~10\% during whole our observations and therefore can not be
proposed as possible OT candidate (GCN 3760). Brighter magnitude in GCN
3760 was obtained because the magnitude of their reference star is
measured with large error in USNO-B1.

Second object is close to the detection limit in our combined image,
which is R=~25.5, but is also extended.

Our finding chart can be found at:

http://hea.iki.rssi.ru/~rodion/050803/r.jpg

We also note, that there is nearby foreground galaxy group in the field.

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