Hallo Paul,
I’m working on a better fix for solving M13 and other global clusters images. The problem is definitely related to the Gaia star database used. It contains several hunderds of M13 center stars at distances of a few arc seconds spoiling pattern match. These stars you can’t image easily from Earth.
The fix seems to work but I’m interested in more M13 (and/or M15, M3) images for testing preferable in RAW of FITs format. The exposure time a few seconds up to maybe 20 seconds. If you could provide me with some samples that would help with further testing.
Cheers, Han