TITLE:   GCN CIRCULAR
NUMBER:  23475
SUBJECT: GRB 181201A: iTelescope optical afterglow detection
DATE:    18/12/01 15:48:16 GMT
FROM:    Albert Kong at NTHU  <akhkong@gmail.com>

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

We observed the field of GRB 181201A (Mereghetti et al. GCN 23469)
with the T31 0.5m telescope of iTelescope.Net in Siding Spring,
Australia. The observation was done with the R-band filter beginning
at 2018-12-01 10:56:18 UT (8.3 hours after the INTEGRAL trigger) for
300 sec. At the position of the Swift X-ray afterglow (Mereghetti et
al. GCN 23471; Page et al. GCN 23474), an optical transient is clearly
detected with a R magnitude of 16.68 +/- 0.03 by comparing with the
USNO-B1 catalogue. The position is also consistent with the optical
transient detected by Podesta et al. (GCN 23470) 18 sec after the
trigger. Given the fading of the optical brightness, this transient is
the optical afterglow of GRB 181201A.