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[RCC] - Help with Rosetta Nebula

Pleiades Astrophoto PixInsight Processing Gradient Removal Request for feedback Help Needed
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Glenn Silverman avatar
Glenn Silverman avatar
Need help processing Rosetta Nebula taken with my new ZWO ASI2600MC Pro with an Optolong L-Enhance filter from a Bottle 7 site. The image is an integration of 35, 5-min subs, with darks, flats and bias frames.  Its been run through Pixinsight with curve and multiple dynamic background transformations. Nevertheless, I can't seem to make a dent on removing the bluish background gradient. I've even tried removing the gradient from both star and starless images after applying StarXTerminator. Is it hopeless, or is there anything I can try to at least reduce the background artifacts? There's also a redish glow in the central area of the image, which I believe is part of the larger NGC2237 DSO. But I can't seem to bring out any of the nebulosity there either. Any suggestions from experts here are appreciated.

https://astrob.in/txgoc8/0/
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Oscar avatar
Oscar avatar
Try increasing the Tolerance (in model parameters 1) to at least 2 in DBE. I noticed it works more aggressively. Also make sure to put enough Samples all around the nebulosity.
Nadir Astro avatar
Nadir Astro avatar
Glenn, I downloaded your JPEG file and cropped it using DynamicCrop in order to get rid of the darkened corners, then used DBE with tolerance 2 and samples of 100-200 and image now looks much better.
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Joe Linington avatar
Joe Linington avatar
Use an image editing program, mask the rosette and use a curve to reduce the blue channel. PI is good but it isn’t the best tool for everything.
Glenn Silverman avatar
Glenn Silverman avatar
Try increasing the Tolerance (in model parameters 1) to at least 2 in DBE. I noticed it works more aggressively. Also make sure to put enough Samples all around the nebulosity.

Your suggestion worked! Thanks,

Glenn
Oscar avatar
Oscar avatar
@Glenn Silverman No problem.
I had only 3-4 days of Pixinsight experience, and it was only by luck that I discovered the Tolerance thing (it helped to remove complex gradients on my images too).

CS
messierman3000
Glenn Silverman avatar
Glenn Silverman avatar
@Glenn Silverman No problem.
I had only 3-4 days of Pixinsight experience, and it was only by luck that I discovered the Tolerance thing (it helped to remove complex gradients on my images too).

CS
messierman3000

I works like a charm.  Thanks for the tip.

Glenn
Glenn Silverman avatar
Glenn Silverman avatar
Now, if I only knew how to reduce the number of stars.

Glenn
Joe Linington avatar
Joe Linington avatar
Starnet++.
pil0t1 avatar
pil0t1 avatar
Something is off in your setup; I had the same setup (2600mc, l-enhance, Redcat 51v2) and shot almost the same frame just last month; the dark band on the right side of the image shouldn't be there. Can you share your light/flat frames (dark/bias doesn't matter much with that camera)? I bet there is something off in your imaging train. 

Let's assume calibration frames are done right and your imaging train is all in good shape. What I would suggest is to use `dynamic background extraction` with about 60ish points making sure none falls over any star or nebulosity, and see the result. You can play with tolerance and see if that helps, but again, I found it more important to have all samples on the background, not stars.


Here is the star reduction script I use, along with the youtube link

https://www.amazon.ca/clouddrive/share/t37K5QLnJq5H7yU9fJq6gpmc8oe823hM0snoi9WUa4J
https://www.youtube.com/watch?v=4rhvHEBmjcM
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