I take it you like the 9.25 ? Where would you rate it between a good C8 and a
C11, m603, mn66 ?
Jerry




David Knisely wrote:

Alex posted:

Hey, last Saturday I was convinced that I'm seeing spiral
structure in M51 in my 8". And that was under much less
than ideal conditions - not very good transparency and some
light pollution.

So, now I have to ask myself: Do I have really good eyes or
really good imagination? :-)

I think that you probably did see the sprial structure, as I have seen it in
my own 8 inch Newtonian on a number of occasions (from a dark sky site of
course). It isn't quite as obvious as the structure is in my 10 inch (where I
can see some of the individual arm segments or the larger star clouds), but
you can easily see it as more than just mottling. One night at my dark-sky
site, I stopped my 10 inch down to 94mm (3.7 inches) to see how M51's
appearance changed. M51 did not show clear spiral structure at that aperture,
but it did show sort of a diffuse irregular ring-like structure around the
brighter core which was distinct enough from the nuclear region to be quite
noticable. At 80mm, the galaxy looked like a circular fuzzy spot with maybe
just a hint of mottling, a small brighter core, and the companion galaxy next
to it. Below 80mm, all hints of mottling vanished. Last night, I had the
NexStar 9.25GPS on M51, and it was one of the finest views of the galaxy I
have ever had with such an aperture. The arms were dim but quite obvious, and
the galaxy took even 297x well, although it was better at 168x. The night was
good enough that I could even glimse the faint connection between M51 and its
companion, along with one of the tidal plumes. Clear skies to you.
--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

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