This chart plots the drift in RA during tracking relative to the star position in the first frame. PEC was automatically trained using an autoguider 4 times. This time I made sure to carefully align the camera to eliminate RA changes from affecting DEC. DEC drift as measured is zero, not affected by RA and indicating excellent polar alignment. RA is shown drifting further and further away from the starting point, around 16-18 arcseconds over 20 minutes. That comes out to less than 1 arcminute of drift per hour, I guess I can live with that...

Here's the real payoff. Very small deviations between frames. The chart below demonstrates that deviation between 10 second frames is now around 2 arcseconds max, and much less most of the time. This is goodness.