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Star defects

Posted: Sun Nov 17, 2013 12:12 pm
by StefanT
Ivo,

I'm not sure, whether this is a ST-bug or not. Quite often stars in my images have coloured "edges" and/or "holes" as you can see in the following cropped image:
Image after initial auto-dev
Image after initial auto-dev
StarDefect-ST.jpg (281.6 KiB) Viewed 5550 times
If I take a look at the original FTS, the holes and edges are not there:

Star defects - Part2

Posted: Sun Nov 17, 2013 12:31 pm
by StefanT
FITS-Image as seen in FITS-Work
FITS-Image as seen in FITS-Work
NoStarDefect-FitsWork.jpg (156.63 KiB) Viewed 5549 times
This is how it looks in FITSWork. I don't have the slightest idea what goes wrong :confusion-shrug: - any idea?

The original file is available here
https://www.dropbox.com/s/9y5369fjirv5v ... ctTest.fit

Please excuse the bad image quality an the heavy CAs - I'm using old M42 lenses at the moment....
Thanks in advance - let me know if I can be of any help

Stefan

Re: Star defects

Posted: Sun Nov 17, 2013 10:54 pm
by admin
While I'm not sure how to replicate this, looking at the data, it seems that what appears to be saturated in the source image is not, in fact, completely saturated. There is color information there that can be recovered (and StarTools does so, while other software will happily destroy/desaturate it). The color information that is there seems to be anomalous though, possibly caused by misalignment, the chromatic abrration or somethingthat went wrong during stacking.
StarDefectTest.jpg
StarDefectTest.jpg (9.46 KiB) Viewed 5540 times
If you want to though, you can white out or overexpose the star cores by various means.

Re: Star defects

Posted: Tue Nov 19, 2013 6:19 pm
by StefanT
Thanks, Ivo! I'll keep on investigating...