[vsnet-grb-info 21009] GRB 180809A: iTelescope optical limit

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23107
SUBJECT: GRB 180809A: iTelescope optical limit
DATE:    18/08/09 21:38:39 GMT
FROM:    Albert Kong at NTHU  <akhkong at gmail.com>

A.K.H. Kong (NTHU, Taiwan) reports

We observed the field of GRB 180809A (Yatabe et al. GCN 23103) with
the T30 0.51m telescope of iTelescope.Net in Siding Spring, Australia.
The observation was done with a luminance filter (400-700 nm)
beginning at 2018-08-09 12:51:14 UT (73 min after the trigger) for 300
sec. At the position of the proposed X-ray afterglow (D'Elia et al.
GCN 23106), we do not detect any optical emission with a detection
limit of about 20 mag by comparing with the Gaia DR2 catalogue.