TITLE:   GCN CIRCULAR
NUMBER:  23160
SUBJECT: GRB 180821A: iTelescope optical afterglow detection
DATE:    18/08/21 19:26:09 GMT
FROM:    Albert Kong at NTHU  <akhkong@gmail.com>

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

We observed the field of GRB 180821A (Tohuvavohu et al. GCN 23158)
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 2018-08-21 17:26:22 UT (46 min after the BAT
trigger). At the position of the Swift X-ray afterglow, an optical
source is marginally detected with a magnitude of 20.4 +/- 0.2. We
propose this source is the optical afterglow to GRB 180821A. Follow-up
observations are encouraged.