SpaceGoat Any recommendations on a IOS app for autoguiding?
The iOS app does not do autoguiding. The tablet simply provides the display and parameter setup functions for ASIAIR's multistar centroid image capture and PHD2 backend. The autoguiding is done as an ad-hoc discrete feedback system in the ASIAIR processor.
Read here to see the GUI for ASIAIR's multi-star guiding:
https://www.yuque.com/zwopkb/asiair
See here to see what some of the parameters in PHD2 do:
https://openphdguiding.org/man-dev/Advanced_settings.htm
The Open PHD Guiding website above has many more documentation.
The Open PHD documentations describe what to do to calibrate the autoguiding. The guiding parameters are not dependent on iOS, but rather on your guide scope/camera's plate scale, the amount and precision of the guide pulses passed to your mount, the amount of torque and backlash from your mount (balance is only a problem if the mount's motor does not supply enough torque), and atmospheric turbulence ("seeing"). Although that last item is much mitigated by using measurements of the centroids of multiple stars ("multi-star guiding").
And finally some understanding of what a German mount's meridian flip does to the guide pulses before and after the meridian flip. There is plenty of documentation on the web on what a meridian flip does, all the way back to Fraunhofer's description of his original mount.
So, you cannot simply copy someone else's parameters in a monkey-see-monkey-do fashion. Even nightly variation in "seeing" will affect how well you can guide (and the need to back off the aggressiveness when seeing is poor from night to night, for example) and even the camera gain will depend on the astronomical transparency of the sky that changes with time and even direction.
Without autoguiding, tracking depends on the precise rate of your RA motor (the Perioidic Error of gears, for example), and the precision of the polar alignment. With autoguiding, the rate of the RA motor is no longer a factor (i.e., no translation term problem); however, image rotation will still occur with very long exposures, commensurate with the polar alignment accuracy.
Chen