Autoguiding...

In terms of the scope, at the moment I have the scope on the wedge and did a quick version of the ccd drift (faster slew speed, shorter exposure). This was very easy to do. The scope is now very close to polar alignment.
Next step is to update the tracking speed. At the moment it's not quite right.
Once this is done, I'll re-check the polar alignment more precisely.
Once these two are fully complete, I'll then train the PEC. I should then be ready for autoguiding. Just have to wait for some clear skies now.
Clear skies,

One point worth noting is that if you use PEC you have to make sure your exposure time is longer than the PEC latency.

Otherwise you get aggressive oscillation between the PEC and autoguider.

Later,

Jed.

Thanks Jed.
Perhaps I shouldl clarify: I wasn't planning to train the pec and try to autoguide at the same time. I was hoping to train the pec permanetly first. Then, once this was programmed into the autostar, I'd have the mount aligned & programmed as much as I could. Then, when it comes to imaging, I would autoguide the scope if still required.

Thanks Jed.
Perhaps I shouldl clarify: I wasn't planning to train the pec and try to autoguide at the same time. I was hoping to train the pec permanetly first. Then, once this was programmed into the autostar, I'd have the mount aligned & programmed as much as I could. Then, when it comes to imaging, I would autoguide the scope if still required.

Hi Michael,

This issue is when autoguding with active PEC (not training). You see the PEC corrections are always slightly later than the error that is being corrected. If you specifiy a intergration time smaller than the PEC latency you can get the autoguider trying to correct an error that PEC has already corrected and you get an overshoot.

Later,

Jed.

An interest point Jed.
Have you seen this happening with the ST4 or DSI ?

Hi Dave,

The general wisdom is to not use PEC unless the periodic error is quite large.

My GM-11 has quite small and slow periodic error so the ST4 does the job OK.

Later,

Jed.

Jed - just out of curiosity...

The AP1200 says that PEC should be used at all times to increase accuracy (though the mount is accurate to 5 arcsec). I think the PEC signals the mount to correct every 100ms. One tip I did see was that autoguiding corrections need only be set to every six seconds or so.

Do you think that autoguiding should be used without PEC in this case?

Cheers

Dave