TITLE:   GCN CIRCULAR
NUMBER:  13250
SUBJECT: GRB 120422A: Zadko observatory - Gingin optical observations
DATE:    12/04/22 20:14:59 GMT
FROM:    Alain Klotz at CESR-CNRS  <Alain.Klotz@free.fr>

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

We imaged the field of GRB 120422A detected by SWIFT
(trigger 520658) with the Zadko robotic telescope (D=100cm)
located at the observatory - Gingin, Australia.

The observations started 3.6h and finished 4.8h
after the GRB trigger.

Weather conditions were good but a poor seeing
of 3.5 arcsec does not allow to separate the
GRB afterglow (Cucchiara et al. GCNC 13245) and
the SDSS galaxy J090738.51+140108.3.

We added the r, g, i SDSS images to create an
equivalent of the Zadko unfiltered image.
The star R=16.37 at ra=136.9080750 dec=+14.0119528
J2000 was used as reference. The flux ratio
of the reference star and the galaxy shows that an
additional component at R=21.1 should be present
in the galaxy on the Zadko image.

start   end     Rmag  dmag filter
   (h)   (h)
   3.6   4.8     21.1  0.2  CR