Focus position versus temperature...and also side of pier?

[Tom Krajci]

See attached jpeg.

This is the analysis of focuser position/temperature from last night's log for the AAVSO Bright Star Monitor (BSM)...CGEM mount, 60mm Tak, MoonLite focuser.

Data was collected automatically using AcquireStar in FocusMax, with ACP Scheduler doing a focus run every hour for the entire night as it slewed everywhere...covering probably 150 targets..

I did not do a rigorous check to see what side of the meridian each focus run was performed...but the pattern seems to be that one side of the meridian gives a focus position different from the other side of the meridian...so based on that assumption is how I parsed the data set to east/west sides of the sky. (I know the first focus runs, at warmest temperature, were performed east of the meridian.)

...this may be an interesting trend that many GEM users discover about their rigs if they take enough data. But we can't answer that unless we get more data from more scopes and different types of mounts.

Anyway, I think I have a decent value for focus/temperature slope for this rig. (But does FocusMax allow me to enter a non-integer value into the temp/focus slope data entry box?)

Progress is made, but with some bumps along the way....

PS. Yet another reason to hate German mounts. I need to weld more forks. But yes, I also need to find and eliminate the flop/flexure/shift that the German mount exacerbates.