TITLE: GCN CIRCULAR NUMBER: 30228 SUBJECT: GRB 210610B: optical observations from Burke-Gaffney Observatory and Abbey Ridge Observatory DATE: 21/06/13 00:40:00 GMT FROM: Filipp Dmitrievich Romanov at Amateur astronomer Filipp D. Romanov (Russia) and David J. Lane (Saint Mary's University, Canada) report: Filipp Romanov observed optical afterglow of GRB 210610B (Page et al., GCN Circ. 30170) remotely using telescopes: 0.61-m f/6.5 Corrected Dall-Kirkham of Burke-Gaffney Observatory (BGO, Dave Lane is Observatory Director) and 0.355-m f/6.2 Schmidt-Cassegrain of Abbey Ridge Observatory (ARO, it is owned by D. Lane) on 2021-06-11. Two images (with exposures 240 and 300 seconds) were obtained on BGO with Sloan i' filter; on ARO were obtained two clear (unfiltered) images (with exposures 840 and 900 seconds) and two images (with exposures 900 and 840 seconds) with Cousins R filter. F. Romanov measured following magnitudes of afterglow from comparison to i' magnitudes of nearby stars from the SDSS Photometric Catalogue DR12 (Alam et al., 2015) for BGO images and from r' magnitudes for ARO unfiltered images; from comparison to R magnitudes of nearby stars from USNO-A2.0 catalogue (Monet et al., 1998) for ARO Rc images: UTC midtime of exposure T_mid-T0, h Magnitude Mag. error ------------------------------------------------------- 02:07:55 6.27 17.45 i' 0.12 02:09:15 6.30 17.64 r' 0.03 02:14:20 6.38 17.61 i' 0.08 02:27:12 6.60 17.36 Rc 0.05 02:44:54 6.89 17.78 r' 0.08 03:03:24 7.20 17.50 Rc 0.08 ------------------------------------------------------- Magnitudes were not corrected for Galactic extinction. Images available here: http://www.ap.smu.ca/~bgo/sm/id.php?app=0&id=15162 http://aro.abbeyridgeobservatory.ca/sm/id.php?app=0&id=3325 http://www.ap.smu.ca/~bgo/sm/id.php?app=0&id=15163 http://aro.abbeyridgeobservatory.ca/sm/id.php?app=0&id=3326 http://aro.abbeyridgeobservatory.ca/sm/id.php?app=0&id=3327 http://aro.abbeyridgeobservatory.ca/sm/id.php?app=0&id=3328