Hi!
I'm playing with comet processing with a number of subs of 46P/Wirtanen. I use a Canon 100D DSLR. I have calibrated the subs with flats, darks and biases. Star aligned and Comet alignment done. Following the process described here:
https://pixinsight.com/forum/index.php?topic=8161My problem relates to the subtraction of the comet from the subs. In producing an integration of the comet, I played with sigma (in ImageIntegration, Pixel Removal section) to get rid of the star trails. I produced one integration with sigma 2, and one with sigma 1.2. I think the 1.2-version is better.
But when I use the sigma 1.2-version in the next step, for subtraction, I can not get rid of the comet. However, if I use the sigma2-version, it vanished completely. See the attached image for a comparison. Upper row is the sigma 1.2-integration and one sub after using the sigma1.2-integration in the subtration (with comet alignment). Lower row is the sigma2-integration, and the same sub when using the sigma2-integration for subtraction.
Now, I cannot see any difference in thes two comet integrations, except for the removal of the star trails. Sigma was the only parameter I changed. So why does the work so differently? I have tried the sigma 1.2 with and without linear fit and normalization, and any values of rejection I can think of - to no avail.
The images are to be found in a dropbox foider:
https://www.dropbox.com/sh/tst9hd6ykqh2phc/AAB96y-TSaQi9tMzUefKA8xEa?dl=0So what am I missing here? Any ideas on this is warmly welcome!
Magnus
