Hi Nick,
A figure I have seen for the diameter of the nucleus is 1.2km so a quick back of envelope calculation using the brightness of the moon as a reference and assuming the same albedo suggests that the naked nucleus would have a brightness of ~ mag 12 currently.
(distance ratio)^2 ~1000. x (diameter ratio)^2 ~10^7 = 10^10 = ~ 25 mag + mag -13 = ~ mag 12
(corrected)
which is in the ball park of what I would have guestimated it to be from the guider image. I suspect you are right though and the nucleus is indeed hidden from view by dust.
That green channel profile includes a lot of Swan band emission. Here is a vertical slice through the spectrum in a region devoid of emission lines.
It is much narrower with the reflected/scattered component mostly confined close to the centre in a region with FWHM ~ 8arcsec. There is some spread, presumably dust, but approximately 30% of the total flux comes from a region similar in width to that produced by a star in the spectrograph which with my setup is typically ~5 arcsec FWHM (wider than a normal image due to astigmatism in the spectrograph optics and guiding errors)
Cheers
Robin