Strange goings on with my guiding, need explanation…

[Stuart1971]

So I have my mount pretty well polar aligned on a permanent pier, it’s within 3 arc mins, I purposely did not get it any better as the DEC axis has backlash, it an older EQ8, and it allows the DEC to drift slightly and so I just guide in one direction, which pretty much makes the backlash issue moot. But tonight all was well, getting good sub 0.5rms, and the DEC was drifting slightly as usual with a small correction pulses about every 1-2 mins….

Then for no reason the DEC dropped and was no longer drifting and so no guide commands issues and was pretty much perfect below 0.2 rms on the DEC axis, now this has carried on for over 50 mins as I write this, still no guide corrections in Dec and absolutely no drift, which makes no sense, how can it just suddenly not be drifting at all….? The PA has not been altered in months…

RA is just acting like it alway does, a bit up and down and an RMS on the RA of around 0.35…

I am not complaining as it’s a good thing, but also can’t explain it…..Any thought on how this could happen….??

 

[kens]

One possibility: As you know the PA error can be broken down into an Alt and Az related component with the Alt component dominating near the horizon and the Az compnent dominating near the meridian. If one causes drift south and the other north then in between there is a crossover point where there is little or not drift. With the mount rotating you will encounter that point somewhere during the evening.

 

[ollypenrice]

On 19/03/2022 at 01:17, kens said:

One possibility: As you know the PA error can be broken down into an Alt and Az related component with the Alt component dominating near the horizon and the Az compnent dominating near the meridian. If one causes drift south and the other north then in between there is a crossover point where there is little or not drift. With the mount rotating you will encounter that point somewhere during the evening.

 

Shrewd!

😁lly