Here's a reduced PSD file with uncollapsed layers showing the basic processing flow for the
second comet shot C/2014 Q2.
The star mask was generated from the stars stack in Startools and saved as a 16bit TIFF files. One stack was registered on the stars so the comet's core and tail were trailing, then removed with the starmask.
The comet's tail and core were extracted from a stack registered on the comet nucleus, so the stars were trailing and rejected with a sigma algo. The program used to stack the subs and do the data rejection was CCD Stack.
The file is about 4MB. You can download it
here. It's saved in Photoshop CS6 format. If you have any issue opening it let me know and I can downgrade it to a lower versions of Photoshop.