I have an Astro-Physics 1100GTO with encoders and was using SGP 18.104.22.168 when this occured. AP mounts allow you to “move” or shift the meridian several hours east to allow the mount to flip when going to the target earlier than normal. I did this. When clicking on “Slew to target” in the sequencer, it performed perfectly and slewed correctly for the start of my imaging run, where the scope ended up probably 20-30 degrees under the mount in the east, with the counterweights up in the west. This allows you to image across the sky with no flipping during the middle of the night in an imaging run.
Doing this got me right on target, but when I then hit “Center on Target” to confirm that I was exactly on the center of the field I wanted, the RA axis started moving off target, came back to level, paused for a second, and then the scope moved back under the mount to the same position it had started from…and was right back on target again. Worked fine and centered perfectly, but why the extra movement in RA instead of just moving like 50 or 100 pixels during the plate solving portion of the “Center on Target”? Is SGP initiating these moves? Is this a mount safety thing thats interacting in a weird way with SGP?