Allow MetaGuide meridian flip by ignoring recalibration


I have a MetaGuide user who would like to use SGP for imaging and things are working well with regard to guiding, dithering, and autofocus, but there is a small issue with Meridian Flip.

I wrote MetaGuide so it would be easy for apps like SGP to do meridian flips by making sure I handled all the user setup issues within MG. So - you can point the scope anywhere in the sky and enable guiding - and it will be calibrated regardless of meridian, oag, guidescope - whatever. The user needs to set things up properly in MG for it to work - but once it is set up SGP doesn’t need to worry about it.

When SGP does a meridian flip it apparently asks the guide software to flip the calibration data - but MG will do all the right things by itself once it detects a meridian flip.

So can you please disable that check for calibration flip when guiding with MG and a merid flip happens?

Here is a section from the user’s log:

[06-19-19 23:46:19.539][DEBUG] [Pier Flip Thread] Meridian Flip: Telescope command to meridian flip has completed

[06-19-19 23:46:19.542][DEBUG] [Pier Flip Thread] Meridian Flip: Telescope has performed meridian flip

[06-19-19 23:46:19.542][DEBUG] [Pier Flip Thread] Meridian Flip: Flipping Auto Guider calibration data

[06-19-19 23:46:49.553][DEBUG] [Pier Flip Thread] Autoguider (MetaGuide) failed to flip calibration data!

[06-19-19 23:46:49.553][DEBUG] [Pier Flip Thread] Adding sequence level notification: Meridian Flip failed to flip calibration data!

Many thanks!


Frank, if MG don’t need to flip then could it accept the flip command and ignore it?

Hi Chris. Commands from SGP to MG are windows broadcast messages that are one-directional and have no response from MG. So the message here saying MG failed to flip didn’t involve a response or complaint from MG because MG doesn’t respond.

If possible, the code in SGP that says “ask the guide software to flip the calibration” should simply return and not do anything when MG is the guider.

As long as MG has an ascom connection to the mount it can always figure out what is needed for the calibration - once it is set up properly for the user’s equipment.

There are ways to do handshaking by monitoring UDP status broadcasts from MG but I don’t think it’s needed here.

As always I am happy to implement functionality that would help other apps work with MG - but my main approach is just to have MG figure things out on its own so the app has minimal work.

In this case - a meridian flip simply requires stopping guiding, removing the lock on the guidestar, performing the meridian flip, locking on the guidestar, and commencing guiding. The recalibration for the meridian flip and any change of declination is handled by MG.

It would also be possible change the rotator angle and tell MG about that - so recalibration isn’t needed for that either.

Anyway - in this case simply disabling the call to recalibrate after meridian flip, when MG is the guider, is all that is needed here.


Yes, I’ll disable this. Just to be clear we should never call that method?


Hi Jared-

Great! Yes - the method to recalibrate on meridian flip should never need to be called. MG doesn’t need to be told anything special about meridian flip. MG users should be able to set up MG so that the mount can point anywhere in the sky and immediately be able to guide there.

There is still the usual need to disable guiding during the slew - but that is no different from a normal slew between targets.

Thanks very much,


Hi Jared… Guylain here from BackyardEOS… I’m the user Frank is speaking of. I’m trying to use MetaGuide with SGP in my remote observatory in Chile and the meridian flip appears to be the only thing that is preventing me from using MG and SGP.

I would be greatful if this can be addressed. I’m also willing to test any beta you’d be ready to throw at me to get this working… you guys are almost there. If you can remove the flip of calibration data during the flip I think that would be it.

Thank you,