"David Knisely" wrote in message
news
Jan Owen posted:

On nights of exceptional seeing conditions, why not fully dark adapt

your

eyes and see just how faint your scope can go? I have posted an
image
which labels the stars in the immediate area of Messier 57 with
their
magnitudes on my website. My 12.5 inch dob has revealed the 14.7

magnitude

star and using averted vision I can sometimes convince myself that
the
neighboring 15.3 magnitude star is hinting at its presence.

To see the image, go to http://home.earthlink.net/~martinhowell and

click

on "Other stuff"


Martin


...and the central star???

-- Jan Owen

The Central star is about magnitude 15.0, but it takes high power and
*very*
stable seeing to pick it up. Seeing variations can make its tiny Airy
disk
blend into the glow in the interior of the ring. It tends to vanish
unless
the seeing is rock-solid, and often is observed to 'flash' on and off
with
seeing variations. I have seen it in a NexStar 9.25GPS, but it was
*very*
marginal. It should be not terribly difficult in a 12 inch, but again,
if the
seeing isn't very good, it won't be visible in any aperture. Clear
skies to you.
--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/


Yes, the central star tends to both seeing and aperture dependent.

I have seen it in a number of different scopes, but never in anything
below 10", and most often above 12.5", so you are doing something right
with that SCT. And we do have some decent seeing here in Arizona...

But because 12.5" is right at the edge of being able to see it more often,
that's why I was curious as to Martin's experiences. He has bracketed it
in his other observations, if, again, somewhat marginally,
magnitude-wise, so I thought I would ask whether he's seen the central
star with the same scope...

--
Jan Owen

To reach me directly, remove the Z, if one appears in my e-mail address...
Latitude: 33.662
Longitude: -112.3272