TITLE:   GCN CIRCULAR
NUMBER:  30364
SUBJECT: GRB 210702A: iTelescope optical afterglow observations
DATE:    21/07/03 11:42:59 GMT
FROM:    Filipp Dmitrievich Romanov at Amateur astronomer  <filipp.romanov.27.04.1997@gmail.com>

I observed the field of GRB 210702A (Lien et al., GCN Circ. 30351)
using remote telescope T17 (0.43-m f/6.8 reflector + CCD) of
iTelescope.Net in Siding Spring Observatory (Australia) on 2021-07-03.
Two images were obtained from 09:00:31 UTC and from 09:01:57 UTC with
Sloan I filter (60 seconds exposures, BINx1) and one image was
obtained from 09:04:38 UTC with Sloan R filter (300 seconds exposure,
BINx1).

I detected optical afterglow with UVOT position in stacked image with
SI filter (mid time = 09:01:44 UTC, that is 13h 54m 31s after the
trigger) and in the image with SR filter (mid time = 09:07:08 UTC,
that is 13h 59m 55s after the trigger) and measured the following
magnitudes from comparison to magnitudes of nearby stars from APASS
DR9 catalogue (Henden et al., 2016): 18.6 i' +/- 0.4 and 19.0 r' +/-
0.5.

Magnitudes were not corrected for Galactic extinction.

Images available here: https://www.flickr.com/photos/filipp-romanov/51286698321