seaber I'm seeing numbers around 0.67 and then over the course of the night I'm seeing these numbers increase despite being under bortle 4 desert skies with crystal clear seeing....and steadily increase over the night [bolded emphases are mine - chen].
If you are using an ASIAIR, I would recommend stopping and then restarting the autoguiding once every hour or so. When I use an ASIAIR, I usually do that when I refocus my OTA (which I do every 1ºC of temperature change).
The reason is this: the adequate polar alignment numbers that you read about are associated with field rotation over a short exposure time, i.e.., field rotation over only 2 or 3 minutes. When you use multi-star guiding, you are averaging the centroid of multiple stars, and their relative position depends on field rotation over a much longer time, like over hours. (I had warned ZWO to look out for this when they were starting to implement multi-star guiding, and to use a very slow moving average to mutate the asterism; but as usual, it fell on deaf ears -- or, they simply don't even grok the problem).
Basically, over an hour or two of autoguiding, the asterism of stars used in auto-guiding has changed due to field rotation. dx and dy for one star is now different from dx and dy of another star (rotated from one another). Resetting guiding (stop and restart) will reestablish a new asterism (relative position of the multiple stars).
See if that makes the mount a bit more tolerable.
By the way, this problem does not exist with single star autoguiding.
Chen
