Lovejoy - reprocess

[fwm891]

Been trying to get a starry background along with a 'fixed' comet image and really failed before - this ones not too bad but there are still a few artefacts around to be sorted:

[astrodam]

Nice image Francis,

What method did you use achieve this image?  I have only been able to get a sharp comet Lovejoy with trailing stars using DSS. 

[stargazerslivingroom]

Lovely, Francis. I can only think it's very difficult to keep the stars round as the comet moves but I think you've nailed it with this one.

The colour really makes it for me.

Excellent.

Steve

[tingting44]

really, really nice mate! i cant wait to image my 1st comet, when i get some time off work and when the skies are clear,

[sologuitarist61]

Excellent image!

[fwm891]

Nice image Francis,

What method did you use achieve this image?  I have only been able to get a sharp comet Lovejoy with trailing stars using DSS. 

Thanks All for the comments.

Damien,

I've had to approach this by building two images: one stack of the sub exposures of the star background and let the comet blur (not too bad as the comet didn't move very far during the session), then a second using the same subs where I've registered the comet head manually and let the stars trail. Both used a Median stacking mode to reduce the intensity of the stars. Both the stacking sessions were done in AstroArt 5.0 using the preprocessing routines.

Then when I had the two images I placed one over the other in PS and registered them both.

For the stars I selected the layer with the stars and blurred comet selected one star then asked PS to select 'similar' so all the stars were selected. I then enlarged the selection by 5 pixels and feathered the selection by 3 pixels. Copied this selection and pasted into a new layer.

There were a couple of bits of the comet that had pasted over with the stars so those were removed with the eraser. Next I went to the comet layer and made a feathered selection (40 pixels) around the comet head and tail, copied that and pasted that into a new layer.

With the dropper tool I selected the background colour and pasted that into a new layer under the other two. Then played with levels until I got a good match across the star and comet layer with the background.

Merged the 3 layers and further adjusted with levels and curves. Final image cropped and saved.

[astrodam]

Thanks All for the comments.

Damien,

I've had to approach this by building two images: one stack of the sub exposures of the star background and let the comet blur (not too bad as the comet didn't move very far during the session), then a second using the same subs where I've registered the comet head manually and let the stars trail. Both used a Median stacking mode to reduce the intensity of the stars. Both the stacking sessions were done in AstroArt 5.0 using the preprocessing routines.

Then when I had the two images I placed one over the other in PS and registered them both.

For the stars I selected the layer with the stars and blurred comet selected one star then asked PS to select 'similar' so all the stars were selected. I then enlarged the selection by 5 pixels and feathered the selection by 3 pixels. Copied this selection and pasted into a new layer.

There were a couple of bits of the comet that had pasted over with the stars so those were removed with the eraser. Next I went to the comet layer and made a feathered selection (40 pixels) around the comet head and tail, copied that and pasted that into a new layer.

With the dropper tool I selected the background colour and pasted that into a new layer under the other two. Then played with levels until I got a good match across the star and comet layer with the background.

Merged the 3 layers and further adjusted with levels and curves. Final image cropped and saved.

Thanks for the info Francis, I'm still on my way up the AP slope so any tips are most welcome. 

I'll see if I can do what you've explained using the software I have so far (DSS, GIMP2) with my last set of Lovejoy data.

All the best