Ernesto,

The "shadow of the nucleus" feature is generally much broader and has
been seen in many comets. C/2020 F3 (NEOWISE) showed it well. There are
plenty of examples in the archive for that comet and others:

https://britastro.org/cometobs/2020f3/thumbnails.html

This is a much thinner line that was a continuation of the anti-tail and
was most prominent at plane crossing so I think it is a different effect.

Nick.

On 19/10/2024 20:53, walcom77 wrote:
> Hi Richard, Nick
>
> That dark line was visible since at least the end of September in my
> images. I think it is what they often call in comet literature the
> "shadow of the nucleus".
>
> Clear Skies,
> Ernesto