Crazy PHD graph

[lukebl]

I am having trials and tribulations with my old NEQ6 as discussed in another thread, and fear I may have irreparably damaged it.

Can anyone suggest what might be happening in this PHD Guiding graph here? As you can see, there is an oscillation over a period of about 12 minutes, which increases over time to a huge spike.

[david_taurus83]

Looks like periodic error. The spike could be a bit of dirt or damage on the worm. Apart from the spike it appears to guide quite well?

Edited May 18, 2020 by david_taurus83

[lukebl]

52 minutes ago, david_taurus83 said:

... Apart from the spike it appears to guide quite well?

No the guiding's terrible! As you see from this single 4 minute frame, the mount appears to jump periodically.

[david_taurus83]

Sorry, I looked at the total RMS error. The peaks look very bad and your sub says it all as well.

[david_taurus83]

Just looked at that other thread and you do seem to be having a bit of a mare with it currently! FWIW, my AZEQ6 developed a bit of rocking/backlash in the Dec axis after 6 months from new. I followed the AB guide on adjusting with the 2 work screws and it fixed it so the guide is not all that bad. Just need to use a bit of common sense when tightening things.

 

BTW, what is your pixel scale at 1.6m focal length?

[lukebl]

5 hours ago, david_taurus83 said:

BTW, what is your pixel scale at 1.6m focal length?

It's 0.58"/pixel. I know. Way oversampled!

[michael8554]

Okay, can't see the RA guide pulses, so can't tell if it's the mount moving first and then PHD2 correcting, or vice versa.

12 minutes is 1.5 x 8 min worm period, can't picture how that would happen.

Post a 12 minute Guide Assistant run, which will show the unguided RA behaviour.

Michael