TITLE: GCN CIRCULAR NUMBER: 30181 SUBJECT: GRB 210610B: iTelescope optical afterglow observations DATE: 21/06/10 23:16:52 GMT FROM: Filipp Dmitrievich Romanov at Amateur astronomer I observed the field of GRB 201223A (Page et al., GCN Circ. 30170) with remote telescope T18 (0.32-m f/8.0 reflector + CCD) of iTelescope.Net in observatory AstroCamp at Nerpio (Spain). Two images (with exposures 300 seconds, BINx1) were obtained with Astrodon luminance filter on 2021-06-10 since 21:40:19 UTC (1 hour 48 minutes 52 seconds after the trigger) and since 21:47:05 UTC (1 hour 55 minutes 38 seconds after the trigger). I clearly detected the optical afterglow with position: RA 16:15:40.38 Dec +14:23:56.5 (+/- 0.15"). The following magnitudes were measured from comparison to r magnitudes of nearby stars from Pan-STARRS DR1 catalogue (Chambers et al., 2016): 17.33 (+/- 0.033) and 17.281 (+/- 0.029). Magnitudes were not corrected for Galactic extinction. Stacked image available here: https://www.flickr.com/photos/filipp-romanov/51238249632