Meridian Flips, then goes back after first plate-solve of Centering

Hello everyone,

I’m very frustrated with the Meridian Flip procedure in SG Pro.

On the last two imaging sessions this is what happened:

Take a bunch of data and SG identifies that the flip is coming sooner than the duration of the next exposure and invites you to “do it now” or “wait it out”. I chose “do it now”.

So it does the flip just fine, and when it takes the first plate-solve image of the “re-center” routine after a flip I see my target in the frame but after solving the image, the mount now swings around all the way back to the pre-flipped position as if it’s trying to re-center it there, even though all it had to do was nudge the scope a couple arc-minutes after the flip and it would have been perfect.

So I aborted the flip after the scope was all the way back where it started, and did the flip manually by just using RA/DEC numbers which gets you fairly close although is time-consuming. After “reminder” plate-solve I tell it to Center the object and it goes back around to the preflipped position AGAIN!!! Unbelievable…

AstroPhysics AP1100GTO (less than a year old)
Running the APCC software of course ( I have custom Meridian limits set)
Plate Solve Software is Pinpoint with the UCA4 catalog (I believe)

Any ideas?

I have a camera rotator on this scope; could the ‘go back’ somehow be related to the reversal of the image for the first plate-solve? Do you think that if I rotate the camera 180° before the flip that SGPro would be ‘fooled’ into thinking it’s looking at the same piece of sky it was and just go ahead and touch it up? Centering works fine at the beginning of the session but after a flip, it’s Armageddon!!!

Bill Gwynne
Hilton Head South Carolina

This almost certainly means that your mount supports the explicit flip command but I honestly can’t remember how the AP mounts work. Logs would help here, but what it seems like is happening is that SGPro asks the flip question, performs an explicit flip, then during the centering routine, SGPro will issue a slew command to correct the framing position and then the mount is deciding this would best happen on the other side of the meridian. Unfortunately there is no sort of ASCOM control over a mount where we can say slew to these coordinates, but make sure to do it from this side of the meridian. Are there any AP specific settings that would prevent the mount from flipping back to a target when you flip early?