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GCN Circular 3853

Subject

GRB050820A: RTT150 optical observations

Date

2005-08-22T12:40:21Z (19 years ago)

From

Irek Khamitov at TUG <irekk@tug.tug.tubitak.gov.tr>

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

report:

      We have observed the OT of GRB 050820A (GCN 3829Not found
 
 
) with the
Russian-Turkish 1.5-m telescope (Bakirlitepe, TUBITAK National
Observatory, Turkey) in two consequative nights .
      We made a series of exposures in Rc between UT 18:35 - 22:15, August 
20, 2005, and in BRcIc between UT 22:46-01:15, August 21/22, 2005. 
Moonlight produced variable background in all images for both nights. The 
afterglow is clearly detected in all bands. Using  Henden's stars (GCN 3845Not found
 
 
)
present in the frames,  we estimated the magnitudes as follow:

   t-t0 		Band 	mag      merr   exptime
(hours, midtime)                       (sec,total)
18.05 		Rc 	19.48 +/- 0.01   900
41.42 		Rc 	20.38 +/- 0.05   1800
40.93 		B 	21.00 +/- 0.06   1800
41.55 		Ic 	19.83 +/- 0.07   1800

    On the basis of our Rc data, we estimeted an alpha index of power-law
decay for the observed period as ~ -1.0.

The JPG-images  of BRcIc and color combined image are available at:

http://www.tug.tubitak.gov.tr/~irekk/grb/grb050820a/grb050820A_b.JPG
http://www.tug.tubitak.gov.tr/~irekk/grb/grb050820a/grb050820A_r.JPG
http://www.tug.tubitak.gov.tr/~irekk/grb/grb050820a/grb050820A_i.JPG
http://www.tug.tubitak.gov.tr/~irekk/grb/grb050820a/grb050820_bri.JPG

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