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GCN Circular 35282

GRB 231205B: Zadko observatory - Gingin optical observations
2023-12-06T07:38:19Z (7 months ago)
Bruce Gendre at UVI <>
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B. Gendre, E. Moore, E. Van Dongen, F. Panther,
D. Coward, J. A. Moore (OzGrav-UWA), A. Klotz (IRAP-CNRS-OMP),
and P. Thierry (AGORA),

We imaged the field of GRB 231205B detected by SWIFT
(Evans et al., GCN 35269, trigger 1200812) with the
Zadko robotic telescope (D=100cm) located at Gingin, Australia.

The observations started 201.6s after the GRB trigger (126.1s
after the notice). The elevation of the field decreased from
25 degrees above horizon and weather conditions were poor,
with high altitude clouds.

The date of trigger : t0 = 2023-12-05T16:43:59.500

The first image is a 10.0s exposure in tracking mode. At the
position of the XRT afterglow (Osborne et al, GCN 35275), we
do not detect any OT with a limiting magnitude of:
t0+201.6s to t0+211.6s : R > 16.2

We co-added a series of exposures:
t0+217.3s to t0+344.2s : R > 17.2

Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction.

N.B. Galactic coordinates are lon=162.4895 lat=-22.7655
and the galactic extinction in R band is 0.3 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.

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