Comet Stacking Options
Here is a brief summary of what you can expect from the different stacking options applied to comet images.

This is the result of the three stacking methods that will be available in the next release of DeepSkyStacker.

The results were obtained from a stack of 8 images of SWAN, 9 dark frames and 7 bias frame and most unfortunately not flat frames.

Mouse over the text to see the different results

Standard stacking The comet position is ignored. The comet is fuzzy and the stars have no trail. Comet stacking : star trails The comet position is used, so that the image is aligned on the comet. Star positions are used to compensate any field rotation. Comet and stars stacking : "star freeze effect" The comet position is used. A first stack is created to extract the comet from the background (special algorithm here). Then a second stack is created to freeze the star (the comet is subtracted from each calibrated and registered light frame before stacking it). Last, the final image is obtained by inserting the comet back in the image.   Although you will need to show DeepSkyStacker where the comet is in each light frame (new user interface here), everything else is automatic.

Call for images
This is only a very small stack and I really need other comet images in order to test the process further.
If you have a medium to large (more than 10) set of RAW images (along with dark, bias and flat frames) I would be really grateful if you can send them to me.

Thanks in advance.