Comet processing: freezing comet, stars and h-alpha nebulosity

[esordini]

Dear all,
I have taken a good number of frames (45 to be precise) of comet 21P (Giacobini-Zinner) that's zipping through constellation Auriga these days.

Twofold problem: the comet is moving fast AND through an area of the sky quite rich in nice h-alpha nebulosity. My (very ambitious, turns out) processing goal would be to produce a final image where everything (comet, h-alpha nebulae and stars) is clearly visible and "frozen".

After much fiddling with CometAlignment and ImageIntegration, I came up with two frames, one with the comet clearly visible and a little residue of the background stuff (stars, h-alpha nebulas, etc.), and one with the background stuff clearly visible but the comet badly mangled (see attachment).

So my question is: is there a way to achieve the desired result in Pixinsight using these two frames? Or do I really have to start over again? Been banging my head over and over again but to no avail.

Thanks in advance
Emmanuele

[alex.vasenin]

I'm not an expert, but I think your second image (which is supposed to be stars-only) could be improved. Usually the workflow is:
1. Register subs on stars (StarAlignment)
2. Register subs on comet (CometAlignment)
3. Integrate comet (ImageIntegration, checking large scale pixel rejection high will help with stars residuals)
4. Subtract comet master from star aligned subs (CometAlignment. have you missed this? if comet residual is high check nucleus offsets)
5. Integrate stars-only images (ImageIntegration)
6. (optional) You can make a third CometAlignmet/ImageIntegration pass to subtract stars from subs and get cleaner comet master

P.S. I actually processing the same thing now