Finally got a chance to test the full system, after the refractor only system worked so well. I’m not out of the woods yet.First, after all the weight has been put back on the mount, the polar alignment has shifted again. This time it wants 5 ticks in Az and 9 ticks in Alt. So, it appears that the original PA wasn’t wrong – the PA changes with weighting down the mount. Don’t know why this is, Bisque seems quiet about this.
Second, I played with the idea of randomizing the order of points when doing the TPoint model. AAG mapper does the points in order, and they are quantized in Alt values. I exported the points into Excel and a) randomized the order, and b) varied the Alt so the points have more variety.
In 50 point runs, random points give the same polar alignment results compared to ordered points. However, you get longer slews on average, and much more large errors on the orthographic view. As a result, you get a bigger circle RMS value for the model. For example, ordered 50 point runs gave a supermodel with 20 arcseconds radius while randomized runs gave a radius of 28 arcseconds. When I ran the big model (374 points) I got a radius of 20 arcseconds instead of the earlier (November) 9.9 radius.
The points have a general NS line rather than being symmetric. Another odd feature, the dD versus n graph shows a linear trend upwards. PWallace notes the abnormalities, but doesn’t have a theory as to cause.
Also, the error buckets are in 20 as bins rather than 5, another reflection of the increased errors from randomizing the points. Note that the effect of randomization would be more pronounced in the bigger model, since the typical slews would be very short in the ordered case. Random slews jump all over the sky, and result in bigger errors. I suspect the randomized model is a better characterization of the scope since one often makes large slews to targets.
test images showed slight Dec drift in 10 minute exposures with ProTrack running. In the East and South ProTrack can almost eliminate the drift now, but not quite. The drift seems to be more pronounced in the West for some reason.