[vsnet-grb-info 2057] GRB050820A: RTT150 optical observations

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3896
SUBJECT: GRB050820A: RTT150 optical observations
DATE:    05/08/28 04:19:16 GMT
FROM:    Irek Khamitov at TUG  <irekk at tug.tug.tubitak.gov.tr>

Z. Aslan, I. Khamitov (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.),
I. Bikmaev, A. Galeev, N. Sakhibullin (KSU/AST),
R. Burenin, M. Pavlinsky, R. Sunyaev (IKI),

report:

     We have continued  observing the OT of GRB 050820A (GCN 3829) with
the Russian-Turkish 1.5-m telescope (Bakirlitepe, TUBITAK National 
Observatory, Turkey)  using TFOSC in R band.
      We made 5*300s exposures between UT 22:40 - 23:05, August 27.  Using
Henden's stars (GCN 3845) present in the frames, we estimated the 
magnitude of the co-added image as R=22.14+/-0.1 (184.25h after the 
trigger).
      The OT is fading with the same power-law decay. Using all the data 
obtained at the RTT150 (GCN3864, GCN3853) we estimated an alpha index of 
power-law decay of -1.06+/-0.03.

The JPG-image is available at:
http://www.tug.tubitak.gov.tr/~irekk/grb/grb050820a/grb050820A_050827r.JPG

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