M108 - Galaxy in Ursa Major

Eamonn,

I can rule out processing artifacts. Have a look at this

www.webtreatz.com/1frame.jpg

This is a section from one single frame. As I mentioned, I tried to identify something in the light path causing this. Perhaps a spider web thread. However I rotated the camera and found this anomaly recurring in exactly the same place with respect to the galaxy, i.e. it rotated with the galaxy.

Maybe a streak on the lens?

Maybe a streak on the lens?

No - Every part of the lens contributes to every part of the image, so a localised smear on the lens will impart a slight blur to the overall image *unless* the smear is at the focal point of one element of the optical train. A smear on the CCD window might have this effect.

If it's rotating with the galaxy when the camera is rotated then the artifact is not in the camera so it must either be in another part of the optical train... or in the sky! Re-imaging with another camera will answer that one.

Phil.

Very nice Mate some great detail and a load of galexies in there to.

Dave and Phil,

Some interesting observations re the 'galaxy's tangential streak'. Let us know when you have diagnosed the problem.

Eamonn A

If it's rotating with the galaxy when the camera is rotated then the artifact is not in the camera so it must either be in another part of the optical train... or in the sky! Re-imaging with another camera will answer that one.

Phil.

Correction - Reimaging with the same camera in a different telescope will answer this question (whether the streak is in the telescope optical train (excluding the camera) or in the sky!)

Phil.