Best use of APCC meridian feature

I just acquired an AP1100.
APCC has a lot of feature to avoid meridian flips.
Does any of meridian features in APCC work with Voyager ?
Or are these APCC features not supported in Voyager and best avoided?

(Is it worth taking the time to setting up the meridian limits in APCC ?
The features sound very cool but I don’t want to waist time on something that can’t work with Voyager.)



I’ve had an 1100GTO since they were first launched. I use APCC and its meridian horizon control capabilities extensively. With Voyager.
Since you just acquired the mount, I’d suggest you learn how to use it and APCC first, particularly defining both meridian and horizon limits. Once those work and you are familiar with what to expect, integrating with Voyager could not be easier. See my previous threads about APCC and the Sequence/Meridian Flip wiki page:

Feel free to PM me.

Hello Max,

Voyager doesn’t support APCC meridian features (and at now we can’t implements it because implementation starting writing additional code in APCC side). Anyway avoid meridian flip is not a choice that Voyager have done but you can manage external meridian flip if occurred outside Voyager, but when is timing to do flip Voyager will do flip for you if configured.

All the best
Leonardo Orazi


If I may; APCC handles meridian and horizon limits if properly configured. My settings in Sequence/Meridian Flip are as shown in the picture below. When Voyager instructs a GoTo, the command goes through the AP ASCOM driver, through APCC, to the mount. If the target is appropriately located, my mount will slew to a CW up position and start imaging like this from the East without needing a flip. It will also track past the meridian up until the meridian horizon (defined in APCC) when it will flip or before if a GoTo is instructed. I have managed my AP mount like this for over 5 years now without a single pier crash.
I am aware that neither Ray Gralak nor AP recommend running APCC and its meridian limits unattended. That is why I suggested to Max to become familiar with his mount and APCC before leaving them on their own. What I do above I do assuming full responsibility for my actions…! :crazy_face:

Hello Roberto,

you are welcome … i just answered in official way because we doesn’t support APCC meridian communication (actually are reserved to SGP).

We have added the external meridian flag you used above to allow situation lke the one you have showed to us. But this is a border line use of Voyager and the flag are reported in red to mean can cause damage to your setup.

Voyager when you use manage meridian in sequence check the pier side to understand if something is changed and anyway check the HA … so if is time to do the meridian flip will ask for it , if the mount report again to be before meridian Voyager retry for 5 time before declare Sequence aborted for error. If APPC can get back to Voyager the right data (and seems this happen from your experience) all work fine and you can manage your meridian externally how you want.

But like Voyager developer i cannot tell to user to do this.

Like astrophotographer, if you all allow me, i dont find problematic do the meridian change when is the right time … but i know some one think different also for logistic reason.

Normalize all the mounts from various brands is not simple … we must be really simple in way to think inside Voyager. Depending from code written from external company is one of the bigger point of failure in automation.

Thanks for your report.

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Great summary. I agree with your approach as developer. Users should take full responsibility if developer doesn’t recommend a certain feature (Ray, AP, you) and I do but it should be noted.

Thanks Roberto,

i add that some users that doesn’t use guide have removed totaly the meridian manage in Voyager sequence and leave the mount running the auto flip … just lost the actual sub running during meridian goto.

All the best

Ray should add support to APCC to communicate the Meridian settings to Voyager. To accomplish this, enough users would need to ask for it.

I’m happy to aid in this discussion on the AP forum but people will need to chime in to gain critical mass.

Voyager isn’t so famous or have all this reputation to obtain this. Manipulate meridian must have a really good reason in my opinion , isn’t a common thing

He did add a ReST API to APCC so it might already be something that can be polled. I’ll ask.

I am on the list I will ask too

Ray says the limit can be polled from the v2 driver.

Yes, there is a way for applications to poll the meridian delay through the ASCOM driver. This should work with or without APCC
(e.g. it can be used with the driver). The command to get the meridian delay in the ASCOM interface function would look something
like this:

MeridianLimitString = Telescope.CommandString(“GM”);

Where “Telescope” is the ASCOM COM interop instance. The value returned is an hour angle string in the format “HH:MM:SS.s#” without
quotes (Hours, minutes, seconds, with a terminating “#” character). A positive value means the mount’s flip point is shifted east.

For this to work the mount firmware requires version “S” of the software if GTOCP3, or any GTOCP4. The version can be read with the
“V” command like this:

VersionString = Telescope.CommandString(“V”);

Sounds interesting
It is up to Leo
I think it would a nice feature to add


But this value is related to APCC setting or the HA in ascom driver?

It’s the ASCOM driver, as delays can be set in the driver too. The driver would provide the delay response with or without APCC.

This is already managed for AP mount … After setting the driver AP with delay just use LST from mount and valorize ap meridian delay field in Voyager. At your own risk.

All the best

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Awesome Leo. I’ll test this out.


I hope you share the steps if this tests out ok. Screen shots of your setup would be helpful


As Leo mentioned, APCC meridian limits are not officially supported by Voyager.

However I followed the instruction by Roberto and I found that Voyager works really well with APCC meridian limits. I ran simulated runs inside for few days and did actual imaging for three nights and it worked perfectly as expected.

Here are my settings in APCC.

If the target is within the east limit, APCC will do the meridian flip in advance for slew requests even though the target is still in the eastern sky.
If the mount hits the west limit after passing the meridian, APCC will flip the mount.
This is done because “Flip” scope is chosen in the action when limit reached drop down list.

In Voyager’s mount setup

For my case I set meridian cross delay by mount to a larger value than the longest west limit in APCC because APCC will flip the mount when the mount reaches the west limit for given declination.

In the sequence meridian tab

You need to check Abort exposure if meridian flip occurs outside voyager and force execute meridian flip operations.

There are two things that you need to be aware of.
If the mount flips when the west limit reaches, you will lose the current sub in progress.
If you use RoboStar focusing and the pier side is west, APCC may flip the mount even though the focus star is on the east (before meridian) if the star is within the east limit.

Most of time I choose a target which can be started with a meridian advance so those two limitations don’t really bother me.

Try this at your own risk but as long as you set the meridian limits correctly and initializes the mount properly, I think Voyager and APCC combination will work without any issue.

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