I am getting a Strange Intermittent Artifact on some of my M42 subs, and I am soliciting PI processing work arounds to salvage otherwise goods subs, probably using PixelMath. This artifact is just in a small portion of the frame. My problem is that M42 is only visible for at most 3 hours (w/ tall trees to East and my house to the West), and this time of the year it is seldom clear. I have not had a clear night in a month and the next week is bad. My main problem is my Red filter as only 36/70 subs are good, yielding only 72mins and most of the dust is in Red. My Blue and Green both have 70+ good subs, so I can use only the non-aberrated subs.
The OTA is an A-P 110GTX w/ 110FF and the camera is a QHY600M. These artifacts are on some calibrated subs, but not on others. All subs are using the same flats/darks. The flats were captured on earlier sessions, but the OTA has remained, undisturbed on the mount on the interim. The problem does not seem to be the flats, as in subsequent nights the problems is there for ~ an hour and then everything is fine for the balance of the evening. Then the problem reoccurs the next night in a similar manner. The artifact seems like some light has been moved to the left, leaving a shadow to the right. The artifact is on all filters within the aberrant timeframes. It seems like something on the sensor glass (more than a dust spot and elongated) that appears and then disappears.
Here is a starless RGB combine, with the artifact being above the Running Man, showing a ~vertical dark gouge with extra light to the left.
I have masters with and without the aberrant subs included. I was thinking about masking an ellipse (GAME) around the problem area, using starless inputs, and adjusting the large set's (w/ aberration) master's masked area using the smaller set's $T/med($T) of the same masked area.
If I had only the larger master (w/ aberration), I have in the past used the following PixelMath to dilute the problems of a moving spot:
iif($T<med($T)-x,max($T,avg($T,med($T)+y)),iif($T>med($T)+x,min($T,avg($T,med($T)-y)),$T))
with x and y being PM symbols that have small input values. You can assume x=0 and y=0 as a 1st approximation.
Any ideas on the PM solution or cause?
Edited by SilverLitz, 21 January 2025 - 01:25 PM.