Quote:
Originally Posted by rat156
Hi John,
Great image.
You can't remove the background stars as you don't have enough delay between exposures. When I do this I usually take a series of LRGB frames, each with a 30 s delay. So that means for 60 s exposures it's at least 6 minutes (closer to 7 in reality with CCD download times) between each L (or R or G or B) exposure. That way when you align on the comet the separate images of the stars don't overlap, hence they can be sigma rejected and median combined out (mostly) of the image.
Attached is a bit of a non-rejected sum of the same comet, just showing the stars, you can see the pattern (also that one of my Luminance frames is out of alignment!).
I really like your image, the tail is so pronounced that the star trails don't matter.
Cheers
Stuart
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Hi Stuart,
I tried an assembly of exposures 6 minutes apart (every other sub), with the same result. Then tried exposures 12 minutes apart to insure there was a significant gap between the stars. No rejection. Hmmm. OK, I'll do more reading on this. It would seem simple enough as I see many of these done on the web and posted here, and there is a lot of ion tail streamer detail that should pop in a starless image.
j