Author Topic: Comet processing  (Read 1013 times)

Offline Gilbert

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Comet processing
« on: 2020 January 29 05:37:09 »
Hallo!

I am new to this forum and relatively new to Pixinsight, and I am just trying to reprocess some comet data according to the recipes by Warren A Keller in his book.

I have registered all subexposures and performed the Comet Alignment. Then I try to use Image Integration to the comet aligned files. In order to optimize star rejection, I have lowered the clipping factor for high pixel values to 0.000, all other parameters are left unchanged. Now the problem is as follows: If I choose a region of interest, everything works fine; most of the star trails are smeared out and the comet is nicely pictured. However, when I apply the same process to the whole picture, the resulting image is extremely bright (also the background). Applying STF to this image causes the STF sliders for RGB to jump to the right (approx. to 80 % position!) and the star trails as well as the comet appear much to bright and noisy. The problem does not occur, if I use a region of interest which is smaller than the whole image by just 10 (!) pixels.

I would be grateful to learn how I could successfully apply the process working fine on a region of interest nearly as large as the original image to the whole image...

Best regards
Gilbert

Offline John_Gill

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Re: Comet processing
« Reply #1 on: 2020 January 29 06:18:53 »
HI,

Have a look at this tutorial https://www.harrysastroshed.com

john
APM 107/700 apo on CGX mount
ZWO Optics - Autoguiding
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... when there are no clouds ...

Offline Gilbert

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Re: Comet processing
« Reply #2 on: 2020 January 30 00:52:03 »
Hi, John!

Thank you for your hint. I know this video and they use the same procedure. My problem is that the Image Integration of the comet-aligned subframes yields a much too bright result while using the same process for a region of interest which is some pixels smaller than the whole area works fine.

Kind regards,
Gilbert

Offline Gilbert

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Re: Comet processing
« Reply #3 on: 2020 January 30 06:38:57 »
Hallo everybody!

I meanwhile could fix the problem by replacing "Normalization: Additive with scaling" by "Normalization: Additive". Thus, the resulting comet image as of proper darkness/brightness and the stars were smeared out because of having reduced Sigma high to 0.000.

Best regards and Clear skies!

Gilbert