Mosaic Stars Issue
 
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2026-10-09 APP 2.0.0-beta48 has been released !

This is mainly a bug fix release for the reported bugs in beta47. In addition it has a significant User Interface performance improvement noticable when you need to process 1000s of images in APP.

2026-10-03 APP 2.0.0-beta47 has been released !

This is a very big release... many code optimizations/rewrites, many parts of APP are much faster and more precise, especially star analysis and registration are much faster ! Big mosaics will go much faster 🙂

And we introduce a new preview filter, which includes the new Adaptive Deep Sky Stretch and a General Levels Stretch, this has been long over due. The old preview filter (the panel on the right side to stretch and preview your data) has not been updated for a couple of years and it is a critical part of any APP session.

Adaptive Deep Sky Stretch or ADSS is a much more intuitive stretch algorithm. It is also color preserving (which is a great new addition in itself ! ) which means that the highlights are no longer bleached, color is maintained from the linear data while stretching. You can simply stretch your data using the sky background level and signal width sliders which work much easier and more intuitive. You no longer need to fiddle with the old complicated sliders with zoom buttons. All the zoom buttons for the sliders are made redundant. And you can enter slider values in the slider value fields yourself. I will make a youtube video in the coming days to explain and fully introduce ADSS. Once the video is ready, it will be highlighted on the forum.

RGB Combine upgrade !. The RGB Combine Tool has been rewritten mostly. The tool is faster and easier to use and most importantly, the Luminance slider to inject a luminance channel or channels into the RGB composite is now working correctly. It no longer bleaches the RGB colors. Combined with the new ADSS preview, you will get much better and easier great composites with great color! I will also explain this in a new youtube video.

Mosaic Stars Issue

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(@endeavor384)
Main Sequence Star
Joined: 6 years ago
Posts: 38
Topic starter  

Hello - I'm doing a 4-panel mosaic and having an issue with the overlapping stars. They're not properly aligning and creating double stars. I've done about 5 mosaics now and the last two have experienced this despite the same settings. Not sure what to really try changing to correct this one. 

 

Settings:

Tab 0: no changes

Tab 1: loaded lights, and existing master files: flats, darks, dark flats, badpixelmap

Tab 2: no changes

Tab 3: default @ 500 which is ballpark estimate what i'd guess to be involved in the overlap

Tab 4: Default with Quads, 1 start 5 stop scale, rest default too

Tab 5: default with regular, multiple-scale, bwmv, scale 1.0 and lanczos-3

Tab 6: Average, quality, checkmark for local normalization, filter = sigma rejection, kappa low = 6, kappa high = 3, 1st degree LNC 1 iteration, 10% MBB

 

Other than messing with the stars on Tab 3 I'm not sure what will help the algorithms better analyze and align the stars.

 

Not sure what other information would be helpful  other than the double stars are ONLY between panels 1 and 3 (side by side on top) and the stars are identical, just one with a slight gap until the other. As it moves way from the center of the 60% overlap area that I'm doing they improve until they align properly. 

 

Mark Carter

double stars

 



   
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(@wvreeven)
Quasar
Joined: 8 years ago
Posts: 2134
 

Hi Mark,

in tab 3 up the number of stars to 2500

in tab 4 use triangles

in tab 5 switch to advanced.

Let us know if that works. 

Wouter



   
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(@endeavor384)
Main Sequence Star
Joined: 6 years ago
Posts: 38
Topic starter  

@wvreeven gave that a shot, pretty much same results with the rest of the settings the same. I did double check the individual frames too to make sure I just didn't have a bad one I missed possibly but in the individual frames, stars look fine. Below is the image of panels 1 and 3 not aligning well, but then where panels 1 and 2 overlap perfectly fine.

good overlap

 

double stars

 



   
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(@endeavor384)
Main Sequence Star
Joined: 6 years ago
Posts: 38
Topic starter  

@wvreeven 

 

To shed light on my process as well, I'm using NINA with 60% mosaic overlap just to ensure there' plenty of alignment points as I had issues with anything less than 40% and I've done a few now with 50% and 60% overlap but for some reason my last mosaic had this similar issue on 2 of the overlaps but since I reduced stars so much you couldn't even notice it, but this one I didn't plan to do much star reduction and it will be very apparent.

 

I am using a newtonian reflector and ensuring that the camera sensor of my asi1600mm is as close as possible to the same degree angle as the other 2 panels. Nina manual rotator wont image until I'm within like 1 degree and I believe between these two frames there was bout .2 degrees difference since I do have to remove the camera to collimate it and it's nearly impossible to get the exact same camera angle when realigning. But I am planning to finish the 4th panel tonight and hopefully won't have this issue on those 2 overlaps.



   
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(@Anonymous 174)
Joined: 9 years ago
Posts: 5702
 

60% is not needed, 10% is already plenty. So if that doesn't work, something else must be up. I would also change the scale start and stop; start to 5, stop to 10, read the tooltips of those settings by hovering over them with the mouse, they might give you some clues as well as how to set them. Also use dynamic distortion correction, that may also cause misalignment when it's off and needed because of your optics.



   
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