I took photos of the optical afterglow of GRB 201223A ( https://gcn.gsfc.nasa.gov/gcn3/29158.gcn3 ) with a remote telescope T18 (iTelescope.Net). I will post the details here and in the GCN circulars later. Now I see that after me Martin Mobberley just finished photographing this with T18.
I have posted the results of my photometric measurements of the optical afterglow: https://gcn.gsfc.nasa.gov/gcn3/29165.gcn3
Stacked image (4x300 + 2x120 + 180 sec.) available here: https://www.flickr.com/photos/filipp-romanov/50753199496
Nice image, Filipp! Very few amateurs have imaged a GRB optical afterglow. You have to be ready and move to the field within minutes, and then usually only have an hour or two before the afterglow fades below most small-telescope limits. If you have access to a bigger telescope, such as something in the meter class, you can often follow afterglows for several days, as they fade rapidly at first and then fade more slowly after a day or so (meaning that you can stack lots of images to go faint enough).
There were a few very bright GRBs in the early days, in the 9th magnitude range, but I haven't heard of anything bright in a long while. Keep monitoring them - you rarely get to image something so distant in the universe!
Dear Arne, thank you for your kind words! It looks rather faint in the images, so the photometry error is large enough. So far, I have only some of points for shooting with remote telescopes, and use them for shooting such rare astronomical events. This is the second time I have been able to photograph the optical afterglow of a gamma-ray burst, the previous time (GRB 191221B) was a year ago: https://www.aavso.org/grb-191221b (it seems that images on the AAVSO forum have been deleted).
With best regards,