Temperature shifts up are substantial so moving a couple hundred steps over a few degrees, seems normal.
Beginning of Pack 12 at 1:35 am
[9/16/2016 01:34:58] [DEBUG] [Sequence Thread] Set start frame temp to 9.32266666666667...
Beginning of Pack 15 at 1:35 am
[9/16/2016 03:28:26] [DEBUG] [Sequence Thread] Set start frame temp to 6.888...
Reason for posting the graphs was to illustrate the random nature and the effects of the Hot Column. Pack 12 normal and results were focused, Pack 13 normal and results were focused, Pack 14 - BOOM hot column, Pack 15 normal and results were focused.
Enabling Smart Focus does not help at all (my scope has an obstruction), especially when using 7 data points. If the AF doesnt get a line on the right, it backs out the focuser 3 spots further than the initial farthest position. When frames move so far out of focus, that stars are faint donuts, the chance of the HFR routine picking up on the hot column increases substantially.
I'll try increasing the number of AF points to 9 but have not had success with that in the past as it causes the problem to get worse, for the same reason above that those frames that are so far out of focus the AF routine can't pick up any of the faint donuts and just see's the hot column. 7 seems to be the happy medium in terms of how far out of focus it goes.
Again, using darks do not help, because the hot column is actually a stuck pixel that bleeds downward, so the intensity varies.
When all is well and good the AF works great. 7 data points does the trick and my 75 step step size brings me in and out out the CFZ no problem. A defect map would be the perfect solution I think.
I should add that the problem is much worse when using Narroband filters.