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GCN Circular 9956

Subject
GRB 090927: Zadko Telescope observations
Date
2009-09-27T20:29:05Z (14 years ago)
From
Alain Klotz at CESR-CNRS <Alain.Klotz@free.fr>
A. Klotz, T.P. Vaalsta, Liang Yan, and J. Zadko
report on behalf of the Zadko Telescope Team.

A. Klotz (CESR, OHP), T.P. Vaalsta, Liang Yan, J. Zadko,
H. Miao, J. Moore, K. Frost, D. Coward, A. Imerito,
D. Blair, R. Burman, P. Luckas, S. Gordon, A. Fletcher,
A. Ahmet, (University of Western Australia)
M. Todd, M. Zadnik (Curtin University)
M. Boer, M. Laas (OHP), P. Thierry (Airbus)

The 1.0m F/4 Zadko telescope started imaging
the field of GRB 090927 (trigger=370846, Grupe
et al., GCN 9945) 110 minutes after the Swift
trigger. A fading source was found within the
XRT error circle (GCN 9946, Gronwall et al.).
The field was observed for 50 minutes using a
preliminary version of a robotic observation
mode.

Preliminary photometry of unfiltered images
taken with an iKon DW436BV camera show the
following initial magnitudes of the optical
afterglow:

tmid(min) Exp. Time  R Magnitude
-------------------------------------
110           42s    >16
126          540s     19.8 +/- 0.5
158          360s     20.0 +/- 0.5

The fading seems to have low decay
which is encouraging to perform
spectrocopy in the next hours.
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