in PRISM v9 (and coming v10), we can add some marks on a CCD image after acquisittion. Thi is very useful for exemple on the guiding camera to mark the position of the slit or the optical fiber hole.
This is what I have done on my setup and it helps for centering a star on the hole before starting autoguiding:
The how to do it is indicated on PRISM forum (french but Google Translate should do the trick):
http://www.prism-astro.com/forum/viewto ... 6732#p6732
Here is a screen printout of my own configuration to do this:
Hope this helps...
Cordialement,
Olivier Thizy
http://observatoire-belle-etoile.blogspot.fr/