M16 Eagle nebula Hubble Palette

[Carole]

This is my last image from Kelling.

Ha 5 x 1200secs
Oiii 3 x 600secs binned x 2
Sii 3 x 600secs binned x 2
Atik314L, Skywatcher Ed120 and NEQ6
Captured in Artemis, stacked in AA and processed in Registar and Photoshop.

[MarkH]

Fantastic Carole, I wouldn't worry about the colour of background stars if you can get nebulosity colours like that.

[Carole]

Thank you Mark

Carole

[MarkS]

I love the Hubble palette on this target. 

However, there does appear to be some colour fringing on the contrasty parts, giving the impression that the layers are not properly aligned.

Mark

[Carole]

giving the impression that the layers are not properly aligned.

Yes Registar which is normally the ultimate weapon for doing this, did not align 100% accurately on this image, much of it was fine but there were some small areas where it did not.  I tried it more than once and there was no improvement, I therefore had to resort to some manual manipulation where it was more obvious. 

Carole

[MarkS]

Thinking about this, if you took it at Kelling then it must have been very low in the sky and so the subs likely contain distortion caused by atmospheric refraction.  Since the distortion is non-linear it can often be impossible to get complete registration right across the frame.  This is probably the problem you are seeing.

Mark

[Carole]

Thanks for the explanation Mark, it makes sense.

Carole

[MarkS]

You may find that if you crop the central region of each frame and register them then the central region may come out better.

Mark

[Carole]

You mean register it in sections and then do a mosaic? 

Yes might give that a try when I have some spare time.

Carole

[MarkS]

You mean register it in sections and then do a mosaic? 

Yes, but you might get away with just re-doing the central section (where it shows most) and overlaying it onto the original.