[vsnet-grb-info 28189] GRB 210619B: iTelescope optical afterglow observation

[GCN Circulars]

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  <filipp.romanov.27.04.1997 at gmail.com>

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