I observed the optical afterglow of the extremely bright GRB 221009A = Swift J1913.1+1946 (Dichiara et al., ATel #15650) remotely using 0.61-m f/6.5 Corrected Dall-Kirkham telescope of Burke-Gaffney Observatory (Lane, 2018, RTSRE, 1, 119) on 2022-10-10. Twelve images with exposures of 300 seconds and Iс filter were obtained, midtime of the first image is 02:06:45 UTC (11h56m after the trigger), midtime of the last image is 03:09:02 UTC (12h58m after the trigger).
I clearly detected the afterglow and measured (aperture photometry, without deblending) following magnitudes of the afterglow from comparison to transformed (from Lupton 2005 formula) magnitudes of nearby stars from the Pan-STARRS DR1 catalogue (Chambers et al., 2016):
Time (UTC)//Ic magnitude//Error GRB221009A 20221010.0880 15.54I RFD 0.12 GRB221009A 20221010.0919 15.60I RFD 0.10 GRB221009A 20221010.0958 15.54I RFD 0.11 GRB221009A 20221010.0996 15.60I RFD 0.11 GRB221009A 20221010.1035 15.64I RFD 0.12 GRB221009A 20221010.1074 15.59I RFD 0.11 GRB221009A 20221010.1119 15.67I RFD 0.11 GRB221009A 20221010.1158 15.69I RFD 0.10 GRB221009A 20221010.1197 15.69I RFD 0.11 GRB221009A 20221010.1235 15.64I RFD 0.12 GRB221009A 20221010.1274 15.70I RFD 0.13 GRB221009A 20221010.1313 15.92I RFD 0.13
Magnitudes were not corrected for Galactic extinction.
FITS files available here: https://observatory.smu.ca/~bgo/sm/id.php?app=0&id=20769 and https://observatory.smu.ca/~bgo/sm/id.php?app=0&id=20770
Stacked image: https://observatory.smu.ca/~bgo/research/GRB_221009A.jpg