TITLE:   GCN CIRCULAR
NUMBER:  19410
SUBJECT: GRB 160509A Gemini North candidate afterglow
DATE:    16/05/09 17:08:50 GMT
FROM:    Nial Tanvir at U.Leicester  <nrt3@star.le.ac.uk>

A. J. Levan (U. Warwick), N. R. Tanvir (U. Leicester),
S. B. Cenko (NASA/GSFC), D. Perley (DARK) report on behalf
of a larger collaboration:

We observed the field of Fermi/LAT GRB 160509A
(Longo et al. GCN 19403) with the Gemini North telescope
on Mauna Kea, beginning at 14:45 UT during morning twilight,
approximately 5.75 hr post-burst.  Consistent with the
refined X-ray afterglow position reported by Kennea et al.
(GCN 19408) we detect a faint source with preliminary
magnitudes of r=23.52+/-0.15, z=21.35+/-0.30 (calibrated
via SDSS stars in the field).  We cannot make any statement
about the variability of this source at the present time.

The position of the source is 20:47:00.93 +76:06:29.2 (J2000),
accurate to about 0.5" in each coordinate.

The fairly red r-z colour could be explained if the burst
was at a high redshift of z=5-6, or alternatively at a 
more moderate redshift with some extinction in the host
galaxy.

We acknowledge the rapid response of the Gemini staff, in
obtaining these observations.