Can guiding counteract bad polar allignment

[garethmob]

Hello guys

Just wondering can guiding on an imaging scope counteract bad polar allignment?

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[lensman57]

Hello guys

Just wondering can guiding on an imaging scope counteract bad polar allignment?

Sent from my iPhone using Tapatalk please ignore any spelling typo thingys

No, guiding is supposed to correct small errors in tracking due to several reasons, a slight error in PA is one of them but bad polar alignment is not. If you polar align  so you can have 60~ 120s unguided exposures with minimal trailing then guiding will probably cope up to 600~900 s expoure but it was not intended to cope with bad PA.

A.G

[Ant]

Yes it can, but only up to a point.

But even though the single star will be guided on, the whole FOV will end up with field rotation.ANT

[garethmob]

Thanks guys

i was looking at trying my best to get the PA spot on which gives me around 30 - 50 seconds in a 70mm scope and using a guide camera to try and take it to 5 minuits with the AT.    think my next thing to get is a nifty fifty  as well as guide camera mini scope to fit on the megres and i be ready

[ollypenrice]

The answer is, as the short thread as a whole concludes, is yes. But not indefinitely!!

Olly

[andrewluck]

As you're using an Astrotrac the answer is no because the AT only guides in RA. Thus it will correct for errors in tracking speed but not PA which results in DEC drift.

I was never convinced of the benefit of guiding with an AT as the periodic RA error was too small to be noticeable with the shorter focal lengths that you use on them. Keep working at finessing the PA though. On occasion I was able to get 10 minute exposures at 135mm.

Andrew

[psjshep]

The longer the guided image, the more it will show up any imperfect polar alignment - the chosen guide star will look nice & round, but rotation will ensure around it depending on how far out the alignment is