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.
Hi,
Last night I took in total 2h of L, R, G and B data of NGC 891. It turns out there is a magnitude 16.4 asteroid close to the galaxy. When I use LN MAD winsor clip with kappa 3.0 and iterations 1 then the asteroid shows up as a small line in the final stack. Even when I set kappa to 1.5 and iterations to 3 the asteroid isn't completely rejected. Should I increase iterations or lower kappa even more?
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Thanks, Wouter
Did you use dithering while capturing? That should help as well. If not, rejection is the only way and indeed you might want to try more aggressive settings as it's so bright. In such a case I would dial it up pretty extreme until it works and then go back to find a sweet spot.Â
I did use dithering while capturing but that won't help since all objects, including the moving object, are shifted over the same amount of pixels. OK thanks for the tip. Looks like APP treats sigma clipping in a much softer way than PixInsight, which is fine and just something I need to get used to.
A related question: I don't understand the effect of increasing the number of iterations versus lowering kappa. If I understand correctly then kappa is a measure for the level at which pixels are rejected and iterations simply the number of times that the clipping algorithm is used. What I wonder about is if there is a "golden rule" for what works best: only lowering kappa, only increasing the number of iterations or both. I am afraid the answer is "both" though 😉
You don't mention the number of subs for each stack in this situation and i think that is key here. The standard approach is to lower sigma, then increse the number of iterations. I get rid of satellite trails and asteroids in 6 sub average stacks with simple sigma clipping sigma=2 and it=1. You can also try to use median stacks.Â
In total 60 subs: 10 Red, 10 Green, 10 Blue and 30 Luminance. Thanks, I will try median stacks instead of average.
