John Bortle's comments (below) are borne out as seen visually at 1702UT this
evening (Jan 6th):

C/2006P1 (McNaught)
2007 Jan. 6.71 m1=0.0, Dia=2.0', DC=8, Tail=25' in PA
035deg...11x80B...Richard Miles (Dorset, England)

The coma is a further magnitude brighter compared with 24 hours ago and may
very well already have attained a negative magnitude. The tail had more of
a hollow fan-like appearance bright along the two outer edges than previous.
The coma is now visible through even substantial cloud and when clear the
comet can just be seen with the naked eye at the start of civil twilight
(Sun at -6 deg altitude).

The comet has generally been 4 magnitudes brighter than the m1 ephemeris
prediction of the MPC for a few weeks now, whereas that difference may have
now increased to about 5.0 magnitudes.

Richard Miles
Golden Hill Observatory

----- Original Message -----
From: "cnj999" <jbortle@...>
To: <comets-ml@yahoogroups.com>
Sent: Saturday, January 06, 2007 4:31 PM
Subject: [comets-ml] Re: C/2006 P1.


>I call particular attention to the Jager/Rhemann images of January 5th,
> where the enlarged pictures clearly showing a classic "shadow of the
> nucleus" down the center of Comet McNaught's inner tail. To my
> knowledge, this is the first comet to display this wonderful feature in
> some time (a classic feature in many past Great Comets). Over the next
> few days, I would anticipate that this apparent dark "void" will also
> become a distinct visual feature of the comet when viewed with optical
> aid in the evening twilight.
>
> JBortle