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Star Halo Help

Tim Dowling
in PixInsight
I'm having trouble finding a PI tutorial that will help me figure out how to get rid of the star halos in my OIII data. I don't think they are actually star halos but rather something to do with the way the light goes through my lens (Rokinon 135mm) as they don't exist in my Ha and SII data. I see there is a tutorial in Horizons, but I don't want to spend money on that without know that's what will fix my issue. Any help is appreciate. Attached is the (very quickly) stretched OIII data (integrated only) as well as a screenshot from PI of one of the offending stars. Thanks in advance.

Tim

Comments

  • BlockHeadBlockHead
    Wow... well on the good side...they are actually symmetric and not unattractive. But yes, it does put an equipment signature on the image. I agree with you that an Iris will do this as far the lines are concerned. (Is your f-stop all the way open? The circular bit...I am not certain there is a whole lot you can do. I get the star pattern on my images as well. 

    If it really bothers you, you can "steal" the stars from the filter bands that do not show the effect. Either use those stars...or fix the bright ones. 

    Finally.. you could also make the acquisition of RGB stars part of your endeavor. 
    These are the two suggestions I have... substitution or throw out the stars entirely and get broadband stars.

    As a practical thing- I would create the narrowband nebula images from *starless* images..and just just add back the stars from one of the "good" bands or RGB stars.

    -the Blockhead
  • Tim Dowling
    I do go starless for all of the processing. However, StarXterminator leaves the halos behind thus my problem. I get these not so attractive blue donuts when I put everything back together (attached). Would either of your suggestions help with that? And yes, f/2.8 which is just one stop from wide open. Any thoughts as to why it's just with one filter? Thanks.

    Tim
    Screenshot 2023-09-06 at 7.54.38 PM 1.png
    576 x 492 - 461K
  • BlockHeadBlockHead
    SXT leaves halos in Ha? 

    I would guess this is an issue in shorter wavelengths due to the coatings on the lens.

    Going to RGB stars *might* help... but you still might have this stuff. This is an acquisition problem that is likely going to be difficult to find a processing solution to.

    -the Blockhead
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