Pacman Nebula


Full automation of LRGB HaSIIOIII acquisition of the Pacman Nebula. Processed in PixInsight. Over 40 hours exposure with 250mm f/8 RCT (QSI683 and Astrodon filters). The NB stacks had the stars removed and were combined with the HST palette. RGB stars were added in afterwards. I still have a little work to do on it to prevent dark halos around some stars.


Very nice! Looks a little bit soft maybe?


yes, I know what you mean. It’s bizarre. In PI it had more bite and more dynamic presentation, when I exported it to a TIFF, it seems to lose something. I’ll have to check whether I messed up in the final stages. It is not the scope, otherwise it would not be resolving those central stars (which I have deliberately softened to give a more natural look with a 12-pixel convolution.


Pretty nice image, yea a little soft maybe. Good colors though.


Very nice blending of the colors. Nice saturation and contrast, too. I agree it looks maybe a little soft, but I prefer that to being oversharpened.


OK, OK, I get it. B minus

I’ll try and do better.


No no, it looks good and is definitely something to be proud of! Way better than a B minus. I just was trying to give constructive criticism. My intention was not to discourage you.


Don’t worry, it is the English sense of humor :wink:
I think I’m going to have another go at processing: I think my CCD has developed more hot pixels since I last took dark frames, the PI LHE tool seems to have created dark patches around stars. I decided to remove stars before stretching the nebulosity, but that has caused other problems, making it look patchy. I’m going to do it the conventional way, with deconvolve on the normal image. It should then sharpen up better. After spending hours on something, you desensitize on what you see. When you come back to it the next morning…ugghh.


The flatness and the ringing are symptoms of overdoing the noise reduction :slight_smile:


The RGB nebulosity had heavy noise reduction but the luminance for the nebulosity only has MURE - but I do not think I sharpened it enough. I have come to realize that the default screen size in PI gives the impression of sharpness due to reduced scale, but you have to double check at 1:1. I should have a new version in the next few days after I have revised my calibration files.


Fjew, you take it up well. :slight_smile: I’m a scientist by trade and giving and receiving criticism is like second nature, I always see it as a positive.


Sometimes it takes someone to vocalize, what you are already thinking unconsciously, to bring it to the front of the mind.


a bit better - still need to work on blending the stars…


Now you done it! I like the dreamy look better, but this is great for stark realism. And it kind of grows on me. - JRC


I figured a new way of blending stars. I reduced the RGB star image to stars only on a very dark background and peak values about 0.8. I then created a new image = (RGBstar * RGBstar) + NebImage. I didn’t need any mask. This blends the diffuse star boundaries better, according to their brightness, rather than fiddle endlessly with soft-edged masks.

I have had a spell of good weather and I’m 20 hours into the next image - SGP (beta 3) continues to purr along while I’m sleeping. I cannot ask for better than that. Now I have to wait for the two weeks of lunacy to die down while the neighbors get over celebrating a bunch of Catholics trying to blow up the houses of Parliament…


Super! Better and better! I like the way that the Boks seem to hang out in 3D.
You should see this on my 55” 4D TV.

I have macphun Aurora HDR 2018. Just running it with the Realistic & Balanced preset at 70% makes it look like a laser etching.


Holiday season and more time to consider my processing options. This time, processed nebulosity without stars and took my processed star image, removed the residual layer and used an expression in the form $T +(Star^1.5)/1.2 to blend in the stars. They do not have little halos around them anymore. I also remembered to change the color mode to sRGB before uploading to forum.