You're Barred

Kylie -> John, John->Kylie

Oooh! I see what you mean.

If you can polar align to this kind degree, you'll find even when autoguiding that your images will improve (the guiding corrections will be lower since the guider won't need to send corrections to the mount for both drift and PE).

Before there's a barrage of replies... Autoguiding does of course mainly help eliminate drift due to 'poor' polar alignment (and also, to an extent, non-orthogonality of your OTA on the mount). If your PE is high, it'll also help eliminate that too - though only for short exposures. I guess what I'm saying is that for long focal length deep sky imaging, you really need to nail polar alignment and reduce PE as much as you can to assist your guiding system.

Of course, your autoguiding system will also introduce potential errors if its a piggybacked system (orthogonality of the two light paths to each other and to the mount and flexure).

Am I rambling? :oops:

Dave

Nice image Dave, even despite the lack of exposure time! One thing I've always liked about this galaxy is that, even though it is a two-armed barred spiral, there looks like 3 spiral arms around the outside! You've almost captured them!

Seanie.

Hmm - didn't know that Seanie. I can certainly make out more than, what looks like, two spiral arms.

I checked some other images of 109 - this seems to be a very good amateur image: www.obspm.fr/messier/Pics/Jpg/m109pbl.jpg

It was taken with a 600mm (24") scope.

Cheers

Dave

Grand image Dave.
Dave G is right, we need a common shadded bar with which we all calibrate our monitors to, its become evident to me particularly over the last week or 2 that different people are using diffferent monitor brightness/contrast settings which is confusing.

Something like this perhaps:


You should see black on the left side, white at right and 19 shades of grey in between.