Robin, Yes you’re right about

Forums Comets Spectrum of Comet 46P/Wirtanen Robin, Yes you’re right about

Nick James

Robin, Yes you’re right about the nucleus diameter (I was thinking it was around the same as Rosetta’s actual target, 67P, but it is quite a bit smaller. Your calculation for the bare nucleus mag is pretty good. JPL Horizons gives a nuclear mag on Dec 9 of 12.85. I get mags of 11.91V, 11.30R in an 11 arcsec diameter aperture and the R profile is definitely broader than G close in (R is mainly dust, G is mainly gas). I think you are seeing the inner dense dust cloud around the nucleus which is probably around 1.5 mags brighter than the nucleus on its own.

This plot was obtained using a widefield system with a pixel size of 2.77 arcsec.