M13 - Arc of light - Fixed using EZ Selective Rejection method (Paul H)

M13 - Arc of light - Fixed using EZ Selective Rejection method

My best friend and imaging buddy meteoritehunterjim and I have close to identical systems. Both are OPT's 10" RC with Optec TCF 2" focuser and the Astro-Physics CCDT67 - 0.67x Reducer. We both recently imaged M13 and we both wound up with this nasty arc running through our images.

We're at a loss as to the actual cause and if any of you know what is causing this please let us know.

Today I started searching for ways to eliminate the arc and I stumbled upon Adam Block's amazing YouTube called EZ Selective Rejection in PixInsight. Adam does a great job of explaining (as always) so I'm not going to even try to explain the steps.

The video is located here --> https://www.youtube.com/watch?v=ZZVJKo47Ctk

The arc is not in all of my subs so Adam's Selective Rejection works. The arc was in 141 out of 153 subs. Because I only had 12 subs without the arc the background in the selected area was noisy and I used the selected area GAME script mask and then MLT Linear Noise Reduction to get the two backgrounds to match as closely as I could.

SoCal Astrophotography
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Status	Basic failed
Started	...
Astrometry.net job	4655224
PixInsight job	n/a
PixInsight queue size	n/a
PixInsight stage	n/a

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