|
I think Marc hit the nail on the head for you, be interested in knowing from that graph what is your imaging scale (how many arc seconds does each pixel / vertical bar represent), what did you set as minimum movement before a guide pulse is issued (pixels or arc seconds) and what you set your hysteresis value as (I generally go above 30% to try and cancel out seeing fluctuations).
Your RA looks reasonably good - I'd guess that is indicative of smooth gears and reasonable seeing, so yes DEC looks like the interplay of polar mis-alignment and backlash with the lag in PHD and your control system trying to overcome the drift.
It would be interesting if you switched the DEC routine from auto to North or South only - in one direction the mount should just drift off, in the other I would expect to see a similar but improved version of what you have posted above!
Matt
|