PIER-14 Repreocessed Veil Mosaic

Forgot to add - total of 3.6 hours Ha and 5.8 hours O3

Hi Richard, 

A wonderful result indeed viewed here on my tablet. Great processing, and I cannot see the join. I'll add my pennyworth or two about the new data a bit later. Maybe I'm just being far too picky.

Cheers,

Ray 

Hi old_eyes,

Very nice result.

If I can just point a few things:

- "When I did this, I got an image with a very clear red cast on one panel and a green cast on the other panel. Very obvious and I could not find a way to get rid of it." --> Did you try to use LinearFit on each panel? Sometimes it can help if there is issue like this. you can apply it on each mono masters or each HOO panels. You can also try DBE on each panel

- If you check closely the stars, you can see, mainly in the coners (but not only) the stars are elongated (due to tracking issues/tilt) and have color artefacts (greenish top left and reddish bottom right of each stars). You can improve it removing bad quality OIII frames but you can also do it using on your final Camera Raw inside Photoshop. There's a little tool called defringe.

Just a few tips! But very nice procesing and result btw :)

Hi old_eyes,

Very nice result.

 

If I can just point a few things:

- "When I did this, I got an image with a very clear red cast on one panel and a green cast on the other panel. Very obvious and I could not find a way to get rid of it." --> Did you try to use LinearFit on each panel? Sometimes it can help if there is issue like this. you can apply it on each mono masters or each HOO panels. You can also try DBE on each panel

 

- If you check closely the stars, you can see, mainly in the coners (but not only) the stars are elongated (due to tracking issues/tilt) and have color artefacts (greenish top left and reddish bottom right of each stars). You can improve it removing bad quality OIII frames but you can also do it using on your final Camera Raw inside Photoshop. There's a little tool called defringe.

 

Just a few tips! But very nice procesing and result btw :)

Thanks Manuel.

I Used DBE on the individual frames for each filter, as the first processing step.

I do dna-linearfit on panels before assembling into the mosaic.

The alternative route I used (assemble each panel in HOO and then merge the panels using PhotometricMosaic) worked OK. Not sure where the difference in background came from, but I could not get rid of it with any of the usual tools. I will just remember the alternative for next time I see that problem.

You are right, there are some tracking and alignment issues in the stars. I tried to use ChannelMatch to nudge the layers into better alignment, but no success. The shift is different across the field of view. It is probably related to the long-time between the initial collection and the supplementary O3, which included the recent maintenance visit. I am not sure it is possible to do anything about it at this stage (don't use PS so can't try the defringe tool), and at anything up to 1:1 scale on this resampled image it does not really notice. So if anyone is looking at the nebula, it is probably OK.

The more I looked at my first version, the more I felt it was too harsh. So, this is a softer version that does not blow out the highlights so much. I like this one better.

That's a feisty image you have there Richard :)

Steve