GCN Circular 7803
Subject
GRB080603B: RTT150 optical observations, break in light curves
Event
Date
2008-06-04T09:46:50Z (18 years ago)
From
Irek Khamitov at TUG <irekk@tug.tug.tubitak.gov.tr>
R. Zhuchkov, I.Bikmaev, N. Sakhibullin (KSU/AST),
I. Khamitov, Z. Eker (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.)
R. Burenin, M. Pavlinsky, R. Sunyaev (IKI),
report:
The optical counterpart (GCN7792, 7793, 7794, 7795, 7796, 7797, 7799)
of GRB 080603B (GCN 7794, SWIFT trigger=313087) was observed with
Russian-Turkish 1.5-m telescope (RTT150, Bakirlitepe, TUBITAK
National Observatory, Turkey), starting at 03 June, 20:55 UT,
i.e. ~1.3 hours after the burst, using Andor CCD.
A series of 70 frames with 60sec exposure in the R and V bands were taken
for a time span ~ 4.5 hours. The afterglow is clearly detected in all
images. Using RTT150 preliminary calibrated magnitudes for USNO-A2
1575-03195804 star R.A. = 11 46 09.53, Dec. = +68 01 51.3, V=14.2,
R=13.8 mag, the brightness of the OT was estimated on each frame.
V,R light curves are shown at:
http://www.tug.tubitak.gov.tr/~irekk/grb/grb080603B/GRB080603B_lc.jpg
Higher dispersion at (T-T0) > 4 hours must be due to high airmass
( Z ~ 65-70 degrees).
The VR-light curves are well fitted with two power law decay functions
with a break about 3 hours after the burst.
A power law decay indices were estimated in OT VR-light curves as follow:
before the break
alpha_R=-0.59+/-0.03
alpha_V=-0.60+/-0.03
after the break
alpha_R=-1.14+/-0.09
alpha_V=-1.03+/-0.07
The alpha indices before the break are in good agreement with Klotz et al.
(GCN7799) calculated for the time span between 1 and 4 hours after
the burst.
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