I just started do automatic meridian flips using APT. They've all worked out so far but they also have all been LRGB images. I've had the plate solver using 5 second exposures and that's been working so far.
Last night, I tried doing the Eagle Nebula using my HSO filters. Since my HSO exposures need more time than my LRGB subs, I upped the plate solver exposure time to 10 seconds. Everything worked reasonably well right up to when it did the flip and then tried to recenter the Eagle Nebula using the plate solver with 10 second exposures. Unfortunately, it just happened to be on the S2 filter. A 10 second exposure thru the S2 filter is basically blank. ASPS wasn't able to solve the position, APT cancelled the plan. I was able to switch to the L filter and do the plate solving, recalculate the number of remaining images, and restart things.
But that was at 1am and manually intervening in the flip kind of defeats the whole idea of an "automatic" meridian flip.
I could up the plate solving exposure time to 90-180 seconds. That probably would work no matter which filter happened to get selected. But that also wastes a bunch of time, especially if the L filter gets selected!
So is there a more elegant way to handle this kind of situation? I kind of wish APT allowed you to specify which filter to use when doing the plate solving exposures and then switch back to whatever is the next one in the plan. But I don't see anything like that.