Seems the illusion of the tail extending to the Milky Way on 18 January was not
an illusion. Better data from Lester Barnes of Sth Aust shows the faint
extension more clearly, detectable length around 37 degrees. Image reproduced
with permission, 8 x 3 minutes with 24mm lens at F2, using Astro 40D at ISO
1600, circa 12:00 UT:
http://i727.photobucket.com/albums/ww271/Rob_Kau/Lester18Jan2012.jpg

The tail has not been detected coming through the MW in a couple of attempts but
it would have to be detectable for well over 60 degrees for that to happen.
Given its drop off in faintness you'd have to think that is unlikely.
Detectable tail length is not changing much because the comet 'head' is keeping
a relatively stable distance back to the MW as it moves. So this exercise of
deep wide inverted shots is not telling us much more information about the long
tail, other than that it remains detectable.

Cheers -

Rob Kaufman
Bright, Victoria, Australia