GCN Circular 3864
Subject
GRB050820A: RTT150 optical observations
Event
Date
2005-08-24T12:26:30Z (20 years ago)
From
Irek Khamitov at TUG <irekk@tug.tug.tubitak.gov.tr>
I. Khamitov, Z. Aslan (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) on the nights of August 22 and 23 in B,Rc,Ic bands.
We made a series of exposures between UT 20:23 - 01:33, August 22/23,
and between UT 20:09-00:34, August 23/24, 2005. The afterglow is still
clearly detected in all bands. Using Henden's stars (GCN 3845) present
in the frames, we estimated the magnitudes as follow:
t-t0 Band mag merr exptime
(hours) (sec,total)
64.39 B 22.24 -/+ 0.06 7860
64.43 Rc 21.02 -/+ 0.03 3900
64.53 Ic 20.46 -/+ 0.05 3900
87.57 B 22.57 +/- 0.08 5400
87.72 Rc 21.30 +/- 0.04 2700
87.82 Ic 20.87 +/- 0.09 2700
We note that, on re-examining the co-added image for 21 Aug in B-band
(GCN 3853), we noticed that it included a cosmic ray event close to OT.
More careful calculation has resulted in a fainter value of B magnitude:
21.47 +/- 0.06 (40.93h after the trigger).
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