Calibration Setting...
 
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Calibration Settings for Plane/Satellite Trails?  

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(@whixson)
Red Giant Customer
Joined: 7 months ago
Posts: 85
November 25, 2018 19:59  

What and where are the settings appropriate for dealing with airplane and satellite trails? Normally I have over 20 lights and darks. 

Wayne


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(@schurig)
Red Giant Customer
Joined: 2 years ago
Posts: 65
November 28, 2018 13:30  

Hello Wayne,

The good news is: airplane and satellite trails won't apprear on darks 🙂

And for the lights go like this: When using the outlier rejection filter (in combination with "average" when having approx. at least 20 frames), I always use the default, which is kappa 3 and iterations 1. I ALWAYS check the "create outlier rejection map" to see what pixels were rejected. If the final stack image still contains trails I increase the level of outlier rejection, either increasing iterations or lowering kappa to 2.5. But, I also review all singe frames before stacking and manually delete bad ones, e.g. when there is a heavy trail right through the object.

Kind regards, Stephan


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(@jtrezzo)
White Dwarf Customer
Joined: 1 year ago
Posts: 11
December 6, 2018 17:38  

I am having trouble with this as well. The geosynchronous satellites in Orion, since they are are on EVERY frame and right in the same location, they are not getting rejected. So far I have tried increasing iterations to 2 and lowering kappa to 2.5, but they are still showing up in the integration. 

What is the most aggressive I can get with these settings before damaging the rest of the image? I am using LN MAD winsor clipping, average integration, weights by quality, and have about 350 frames.

This post was modified 4 months ago 2 times by jtrezzo

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(@schurig)
Red Giant Customer
Joined: 2 years ago
Posts: 65
December 6, 2018 17:59  

How do they appear in the image? As as a spot? If they are in every frame at the same position you cannot use outlier rejection. You can use photoshop to erase them.

stephan

 


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(@jtrezzo)
White Dwarf Customer
Joined: 1 year ago
Posts: 11
December 6, 2018 21:11  

They are streaks across the top. See the heavily stretched image here. This was just the first 2.5 hours of data. They aren't the same in every frame by any means but they go right across the same general area and I'm guessing overlap in several frames. 

received 778913689120502


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(@schurig)
Red Giant Customer
Joined: 2 years ago
Posts: 65
December 7, 2018 09:02  

That's difficult. Try outlier rejection with different parameters (start with kappa 2,5 and decrease, increase iterations). But I think the trails cannot be eliminated completely when you describe them such present in every frame...


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(@vincent-mod)
Black Hole Moderator
Joined: 2 years ago
Posts: 303
December 19, 2018 02:43  

Yes that region of space is probably the worst concerning satellite trails. Most seem to be rejected I think, looking at the final stretch, but it might require some extra post-processing to get it completely gone, likely in another program. More aggressive dithering might help (I always do that especially on this region) as well as more aggressive rejection. If it hurts some details, but does remove the trails then that's the trade-off you will have to make given the data. If the date is dithered very well it might already improve.


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(@jtrezzo)
White Dwarf Customer
Joined: 1 year ago
Posts: 11
December 19, 2018 16:51  

Here is the final image. I took more frames (over 300 total) and got up to 6.5 hours and I did dither fairly aggressively every 5 frames. If you look really hard you can see a faint trail where the satellite path was worst, but it is significantly less prominent than the image posted above. So it seems just having more images helped here, as I did not change the settings for rejection.

 

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(@vincent-mod)
Black Hole Moderator
Joined: 2 years ago
Posts: 303
December 19, 2018 23:07  

Yes more images will give you more variation which is then averaged out better. I actually dither every frame for this object (set on High with Sequence Generator Pro), it really helped also with less images.

Very nice image btw, love the brown.

This post was modified 4 months ago by Vincent Groenewold - Moderator

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