[vsnet-grb-info 19315] Swift Trigger 748858: Zadko observatory - Gingin optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21012
SUBJECT: Swift Trigger 748858: Zadko observatory - Gingin optical observations
DATE:    17/04/19 13:33:13 GMT
FROM:    Alain Klotz at IRAP-CNRS-OMP  <Alain.Klotz at free.fr>

A. Klotz, D. Turpin (IRAP-CNRS-OMP), D. Macpherson (UWA/ICRAR), D. 
Coward (UWA),
M. Boer, (UNS-CNRS-OCA), Gendre B. (UVI - Etelman Obs.),
A. Williams (PO-UWA), R. Martin (PO-UWA)
report:

We imaged the field of the trigger 748858 detected by SWIFT
with the Zadko robotic telescope (D=100cm)
located at the observatory - Gingin, Australia.

The observations started 4.25h after the GRB trigger.
The elevation of the field increased from
18 degrees above horizon and weather conditions
were good.

We co-added a two series of exposures:
t0+4.25h to t0+4.40h : Rlim = 20.1
t0+4.65h to t0+5.22h : Rlim = 20.3

No source exhibit a variation flux compatible with
a GRB afterglow. All sources detected by Zadko are
presents in the DR9 SDSS-III image.

Magnitudes were estimated with the nearby NOMAD1 stars
and are not corrected for galactic dust extinction.