[vsnet-grb-info 28202] GRB 210619B: Abbey Ridge Observatory optical afterglow observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30305
SUBJECT: GRB 210619B: Abbey Ridge Observatory optical afterglow observation
DATE:    21/06/22 17:00:39 GMT
FROM:    Filipp Dmitrievich Romanov at Amateur astronomer  <filipp.romanov.27.04.1997 at gmail.com>

Filipp D. Romanov (Russia) and David J. Lane (Saint Mary's University,
Canada) report:

Filipp Romanov observed optical afterglow of GRB 210619B (D'Avanzo et
al., GCN Circ. 30261) remotely using 0.355-m f/6.2 Schmidt-Cassegrain
telescope of Abbey Ridge Observatory (it is owned by Dave Lane) in
Canada, on 2021-06-21.

Eight images (with exposures: 660, 840, 720, 840, 720, 720, 780 and
720 seconds) were obtained with Cousins R filter from 02:29:26 to
04:56:00 UTC. The optical afterglow (with UVOT position) is clearly
(SNR = 11) visible in the stacked image (mid time = 03:42:42 UTC, that
is 1.155 days after the trigger). Romanov measured its magnitude
comparing to transformed (using formula Rc=r’-0.22 from Dymock &
Miles, 2009) r' magnitudes of nearby stars from Pan-STARRS DR1
catalogue (Chambers et al., 2016). The measured magnitude = 20.0 +/-
0.2. Magnitude was not corrected for Galactic extinction.

Stacked image available here:
http://www.abbeyridgeobservatory.ca/images/GRB210619B.jpg