Hi all,
we try to resubmit an e-mail we sent yesterday afternoon to this list
(but it didn't show up yet). Sorry if it will turn out a double
posting.
Cheers,
Giovanni and Ernesto

***************************************************

---------- Forwarded message ----------
From: walcom77 <walcom77@...>
Date: Jan 26, 2007 4:47 PM
Subject: C/2006 P1 (McNaught)
To: comets-ml@yahoogroups.com
Dears all,

We would like to comment about the results of our observations of
C/2006 P1 (McNaught), obtained remotely (near Melbourne, Australia).

On 2007, Jan. 23.43, 25.44 and 26.43 we imaged this comet through a
0.32m, f/9 Ritchey-Chretien reflector + CCD + Red filter (pixel scale
1.3 "/px, FWHM of the field stars almost 2.5"). We detected the
presence of three concentric parabolic shells on the sunward side of
the inner coma (their brightness decreases significantly from the
innermost to the outermost). We measured their offsets from the
central condensation as: 7", 17" and 27" +/- 3", respectively.
An image is available here:

http://tinyurl.com/yrn2p2


Images obtained on 2007, Jan 24.44 by A. Rosner through a 0.09m, f/4.6
refractor + CCD, reveals the presence of a real antitail, placed
inside (sunward) of the comet orbit, whose lenght (perpendicular to
the line of sight) has been estimated to be almost 1.61 Million Km;
assuming that its grains has been emitted at perihelion, their average
speed turns out to be about 1.6 Km/sec. This feature is striking
similar to that observed on C/1962 C1 (Seki-Lines) in April 1962. An
image of this feature is available here:

http://tinyurl.com/22pby7


For comparison, this is an archive image of comet Seki-Lines, where
a similar strucure is readily visible:

http://tinyurl.com/2767ec


Cheers,
G. Sostero, E. Guido (Remanzacco Obs., CARA)

http://www.afamweb.com
http://cara.uai.it