Comet stacking & large scale rejection

[mash.m]

Hi,

i have a set of 110 Pictures taken from C2018/Y1 that move along ngc2903. light data: 30 seconds at iso 1600 taken with a cooled 6D on a 10" f4 Newton. i used this tutorial to use the Comet alignment tool:

http://pixinsight.com.ar/en/info/processing-examples/38/lovejoy-comet.html

but i Always have lots of artefacts left at the stacked Picture. i also tried to stack Frame 1,3,5...n and large scale rejection, but still the same, see attachment. Any hints?

Thanks, Markus

[dld]

I have similar problems while working with wider FOV images. Either a lot of stars remain at the comet integration or if I go too far with rejection, the comet does not get subtracted properly. Also the "stars" integration has a wilder background than a typical integration, which is hard to fix.

My feeling is that the normalization with LinearFit (during the CometAlignment comet subtraction phase) is inappropriate and a better solution must be found, probably using LocalNormalization, or a scaling based on a ROI utilizing the comet only and not the whole image. Why subtracting something from places where there is nothing to subtract?

Any advice will be welcome.