(a lot of A's, P's and C's in those acronyms)

I have recently started using Astro-Physics' new control program APCC, which adds many useful features and functions as a layer between their ASCOM driver and the scope itself.

Bob and Ray Gralak (author of APCC) have helped out with some of my questions, and Bob thought it would be good to reproduce some of that dialog here to help others -- plus I think there are still some unresolved issues.

APCC Pro version includes a pointing model, and its documentation warns about corrupting the model by doing syncs -- so my original question to Bob was

>Should I select “Disable auto-center (sync or re-slew)” in Preferences/General, since doing a sync after building the APCC model will invalidate it. But I would like ACP to do a re-center w/o sync – what determines when/if a sync vs. re-center is done?

> Bob: The driver should return false for Telescope.CanSync. If so, ACP will jog to center.

So I asked Ray Gralak if the AP driver will do that
>Ray: Unfortunately there is no option currently in the AP V2 driver to force CanSync to false. However, it should be ok if ACP syncs to JNow coordinates instead of the J2000.0 coordinates that most catalogs use. That is ACP must convert the Plate solved coordinates to "local apparent"

and to do that...

>Bob: ACP will sync to JNow if "scope needs local topocentric coordinates" is on, indicating that the scope uses JNow. It is undoubtedly on for your AP mount

This is great, because now I can both use the APCC pointing model and have ACP precisely center my target.

But there is at least one more issue -- APCC has features to create precise maps of horizon limits and most importantly meridian limits. The meridian limits allows you to map how far past the meridian you can track at any given declination. For many targets this will allow the scope to track for hours past the meridian without doing a flip. Additionally, again at certain declinations, you can start your imaging session with the scope pointing to a target in the east with the scope on the east side of the pier ("counterweight shaft up"), again allowing long imaging session with no flips.

I asked Bob if ACP will at some point support this and he said:
> Bob: If the flip settings in ACP are set to match the meridian limits in APCC, ACP will take full advantage of any "track past flip point" that is available to avoid waiting for flips. This is described in ACP Help, German mount info. It's also covered in "getting started" as well (by reference).

I am not sure that is the whole story, since the meridian limits feature in APCC is a map of allowable RA tracking as a function of declination, while the ACP setting is one limiting number that is used for all targets.
Do I misunderstand, Bob?


- Barry