Celestron AVX and PEC

[CSM]

Reading up on PEC, PECTool and Pempro.  With PECTool there is the advantage of saving the results of training runs to get an average PEC.  This is said to be of particular advantage for mounts with non-integer gear ratios.  As the AVX has integer gear ratios presumably a single run, if done properly, would be sufficient and last a long time?

[Oddsocks]

Where possible it is always an advantage to create a PEC correction curve using as many measurements as possible and averaged into a single curve, irrespective of the gear ratios used by the mount.

A single measurement can be biased by seeing, reaction time of the observer (if creating a curve visually), backlash, balance of the OTA, nearby ground vibration of the mount, gust of wind etc etc.

Once a good averaged PEC curve is created there is no reason why it should change over time except slowly in response to wear of the gear and worm.

I created a PEMPro curve for a Gemini G41 that lasted ten years and If I remember I averaged about twenty five to thirty individual curves that were guided by guide cam and OAG.

In imaging mode not all mounts respond well to a mixture of normal guiding via guide cam and PEC, some positively fight back at guide cam commands when PEC is enabled and these mounts work best with PEC disabled and just reliant on the guide cam input to correct periodic error and non periodic error, in my case with the G41 I found typical guiding error with PEC disabled was 2 arc sec and with PEC enabled 0.8 arc sec so it was worth while for my mount to use PEC full time when imaging, I can not say how the AVX will respond, you would need to carry out your own test to see which works best, with PEC and guiding or guiding only.

William.

[CSM]

Many thanks William.