Now that 12P has gone from our northern skies (although see below) I
would like to use the same techniques to monitor the near nucleus
brightness of C/2023 A3 (Tsuchinshan-ATLAS) over the next few months.
I've set up a web page with details here:

https://britastro.org/section_news_item/c-2023-a3-observing-campaign

This uses exactly the same Astrometrica settings that were used for 12P
so setup should be reasonably straightforward.

It would be really good to keep our 12P lightcurve going post-perihelion
so if you have access to telescopes in the southern hemisphere please
continue to image this comet and report your measurements to me.

Nick.