[vsnet-grb-info 7944] GRB 090530: RTT150 Optical Observation
GCN Circulars
gcncirc at capella.gsfc.nasa.gov
Thu Jun 4 02:47:31 JST 2009
TITLE: GCN CIRCULAR
NUMBER: 9487
SUBJECT: GRB 090530: RTT150 Optical Observation
DATE: 09/06/03 17:47:25 GMT
FROM: Solen Balman at METU <solen at astroa.physics.metu.edu.tr>
S. Balman (METU), M. Parmaksizoglu (TUG)
Z. Eker (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.)
I. Bikmaev, N. Sakhibullin (KSU/AST)
R. Burenin, M. Pavlinsky, R. Sunyaev (IKI),
report:
We observed the field of GRB 090530 (Swift trigger=353567,
Cannizzo et al.,2009 GCN Circ. 9438) with the Russian-Turkish 1.5-m telescope
(RTT150, Bakirlitepe, TUBITAK National Observatory, Turkey) on
30 May starting at 18:30:37.7 UT about 15.2 hours (0.633 d) after the burst
using the TFOSC CCD (burst detected at 03:18:18 UT with Swift Burst Alert
Telescope(BAT)).
Flewelling et al. 2009 GCN Circ. 9439 found the afterglow at
16.0 mag at 03:18:42.7 UT. Calibrating the data against the USNO star at
RA = 11:57:41.7, Dec = +26:35:43, Rossi et al. 2009 GCN Circ. 9458
obtain R = (22.2 +-0.2) mag 21.3 hrs after burst. They also found a
break in the optical light at around 22 ksec post-burst (see also
GCN Circ.9440-9443, 9450-9452, 959, 9466, 9478 for white light
and UV photometry).
We obtained one 900 sec exposure using the R band filter (Bessell filter).
We used the Swift XRT position derived by Breadmore at al. (2009)
GCN Circ. 9445 to locate the afterglow candidate. We were able see the
source, but unable to calculate a magnitude using PSF photometry with
DAOPHOT within MIDAS software performed on the 13.3 by 13.3 arcmin field
around the candidate. We find a frame upper limit of R = 21.1+/-0.5 mag
at 3 sigma and 21.9+/-0.5 mag at 2 sigma confidence level
calculated using the same USNO star mentioned in the above paragraph.
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