TITLE: GCN CIRCULAR NUMBER: 30292 SUBJECT: GRB 210619B: iTelescope optical afterglow observation DATE: 21/06/21 14:08:05 GMT FROM: Filipp Dmitrievich Romanov at Amateur astronomer I observed the field of GRB 210619B (D'Avanzo et al., GCN Circ. 30261) using remote telescope T18 (0.32-m f/8.0 reflector + CCD) of iTelescope.Net in observatory AstroCamp at Nerpio (Spain). Five images (with exposures 300 seconds, BINx1) were obtained with Astrodon luminance filter on 2021-06-20 from 23:06:46 to 23:36:44 UTC (until the roof was closed due to poor weather). I detected faint (SNR ~ 3) optical afterglow with UVOT position in stacked image (mid time = 23:21:43 UTC, that is 0.974 days after the trigger) and measured its magnitude from comparison to r' magnitudes of nearby stars from Pan-STARRS DR1 catalogue (Chambers et al., 2016): 20.5 +/- 0.4. Magnitude was not corrected for Galactic extinction. Stacked image available here: https://www.flickr.com/photos/filipp-romanov/51261591951