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NGC7000 4-Panel Mosaic Defects Repair

Nimbus7
in PixInsight
I am trying to salvage this project as it was tedious to get to this point.  First of all when rechecking my master flats I cannot really correlate a match up to this issue in those.  Channel Extraction shows my issues in channels B,G.  Wavelet Extraction shows the problem in wavelets 3-8.  Looking for guidance to either remove or miinimize those issues.

Areas marked 1-3 have blue nebulosity that does not belong.  Area #4 is is showing  striations near the Pelican nebula which my guess is some reflection coming from the out of field Deneb.  I have also attached the starless version to show how pronounced this is.  Thanks for any assistance.

Comments

  • Nimbus7
    edited June 2023
    I did recheck my flat subs with a different stretch and I do see a pattern in one position on the left, so I am guessing this was likewise placed in a similar position in all four panels. And a further review shows a slight amount in the Red channel.   Nutz.
    NGC7000_FlatSub.jpg
    985 x 653 - 29K
  • BlockHeadBlockHead
    Hi Bill,

    Well... it appears then that ultimately this is a flat fielding issue with respect to the donuts. 
    It might be possible to use a correct technique that I demonstrate where you have one channel where the information is "good." 

    If we assume the Red channel is OK.. you would take the blue channel in a region around the issue:

    1. Create a preview of this region (say in the Blue data) and drag it out to make a new view. 
    2. Do the exact same thing from the Red (good) image. Same exact preview dragged out.
    3. Use Linear Fit with Blue as the reference and apply to the Red region.
    4. Substitute this region into the original Blue image. 

    It wouldn't be perfect... but it might work. 
    See:

    -the Blockhead
  • Nimbus7
    Will try your recommendations.  I did take another look in the Red channel with a different stretch and could see a much fainter amount.  But will try again just the same.

    Thanks,
    Bill
  • Nimbus7
    Enjoyed the Scattered Light tutorial and applied to these attachments.  Unfortunately my Red channel that I used still had some residual artifact, just the same I think it reduced the problem about 80%.  I wonder if perhaps I extracted the LUM if that would work better or make things worse.

    Next attempt will be to try and remove the reflection striations from Deneb near the Pelican. 

    Thanks for the help!
    Bill
    MosaicDefects_2.jpg
    1080 x 772 - 109K
  • BlockHeadBlockHead
    Yes...if the Linear FIt is good... putting the Lum in each of the channels should work. The nebula will be the correct color roughly. The stars...probably not since their will be a single scaling factor computed. It is worth a shot. 

    -the Blockhead
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