[g__day (Matthew)]

David,

Really - I would have thought regardless of which PEC capable mount one owns, your method of measuring tracking error, determining which component of tracking error was actually repetitive / peroidic error (versus random or seeing error), inverting the PE part of the tracking error to compensate would be largely mount independent. I presumed only the upload feature of the inversion tracking run would be mount dependent.

In answer to your queries, I run a Vixen Atlux mount with the SkySensor2000-PC hand controller v2.05 - generally comptuer controlled via ASCOM -> via a telescope hub under the control of MaxPoint, slaved to both The Sky6 Professional Edition and Cartes du Ciel, guided by PHD using a piggy-backed 80mm Megrez with a Meade DSI off my main OTA a C9.25 with a Canon 400D interfaced to a Meade Motorfocus controleld via a JMI USB link.

The Vixen Atlux has a (advertised) raw PE of around +/- 7 arc seconds peak to peak - so out of the box its exceptionally good. The Atlux is permanently mounted in an observatory. MaxPoint with 16 references tells me the mount is 2 arc seconds high and 1 arc minute East of SCP - will fix that later. I did a 20 minute guided shot of NGC 6093 last night with the primary OTA being a 9.25" SCT - so focal length 2.3 metres - into a Canon 400D DSLR - the stars were perfectly round! Pointing is also surperb - generally my gotos are spot on CCD chip, often dead centre over the entire sky. In 3 star align the mount will automatically account for SCP mis-alignment, position of the tube to account for the air's refractive index, and adjust both motors running to track exceptionally well.

The Vixen Atlux works by doing a PE training run - you have something adjust pointing for about 6-8 minutes (a full revolution of its gears) and it remembers the adjustments and simply loops them continually. The something I have at first used was a piggybacked Megrez 80mm refractor (focal length 500mm) into a Meade DSI into PHD v1.6.1 with a 2 second feedback loop, adjusting in RA only with pulses triggered by only a discreptionacy of over 0.90 pixels.

Hope this helps. Please do explain how type of PEC capable mount (assume GE) varies how you assess pointing error, determining repetitive error from seeing or random error, isolating this part of the curve, inverting it versus simply uploading it to your specific mount type?

Jase

Extremely helpful - thank you too!