If my understanding of the system is correct, the job of tracking the appropriate satellite is passed to the Arduino and this runs the steppers automonously from the rest of the system. I assume that this is performed by passing it a TLE and having a feed from the GPS receiver tell it earth location.
Q. Does the Arduino also know about sun position?
This could help in the alignment of the system, if we know lat/long/ele/time we know were the sun should be… and thus have a good way to set the azimuth at a location. (Elevation is a little easier to set with a buble level)
Maybe we could use some form of target sight to confirm that we’re correct, or even do it electronically. The solar community do sun trackers with 4 photo-diodes, if we just need azimuth we could do it with 2.
Also knowing sun position we could do sun advoidance, which would be very useful for any optical work.