Which stacking algorithm to use ?

[rotatux]

Hello,

I just had a tough time learning to use my new planetary stacking software, cvastroalign (I only work under Linux). Though I didn't understand all options at first, I made my way through by testing and repeated processing of my first jupiter movies.

Still, from the available stacking options "Sigma clipping" [+ Average] and "Sigma clipping median", I wonder which one should be used (I already ruled out pure average, knowing the advantage of sigma clipping).

I have tried Sigma+Average on half of my frames, and have the impression that it gives a result more easily processed with wavelets afterwards, but leaves a somewhat wide "undefined" circle at the edge of the disk, which after wavelets or unsharp mask turns into a distinctive processing artifact. OTOH I tried Sigma+Median on my other half frames, then the edge artifact I got after wavelets was more thin and/or softer, but finding acceptable wavelets settings was much more difficult. I have also compared one frame with both Average and Median and additionnally to the above, noted the disk is noticeably smaller with median (which correlates the wide edges of Average).

IIRC my maths, the median converges faster to its target but has limited precision, while the average is slower to converge but gives greater precision proportionally to the number of frames. So I guess I should only use Median when a low number of good frames are available. However the pros/cons of each let me split-minded...

Advice / Opinions ? e.g. What are you using in Windows-only Registax and why ?