How faint can your scope go?

In Rat's post of 9/7/04, he remarked on his observation of the Ring Nebula:

snip
M57 (of course) - Ring Nebula - PN - LYR - Wow, This is too fun! I noticed
a couple of faint stars, coming in and out of view, lying just outside the
ring (in addition to the Mag 13 one that I usually see), I am going to
check later and see what Mag they were.
unsnip

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

"Martin R. Howell" wrote in message
.. .

In Rat's post of 9/7/04, he remarked on his observation of the Ring
Nebula:

snip
M57 (of course) - Ring Nebula - PN - LYR - Wow, This is too fun! I
noticed
a couple of faint stars, coming in and out of view, lying just outside
the
ring (in addition to the Mag 13 one that I usually see), I am going to
check later and see what Mag they were.
unsnip

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

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

There you go, that's exactly what I needed, thanks, Martin!

I think I got the 14.7 and the 15.3 opposite the mag 13, with the 8"
refractor.

The 15.3 was "gone" more than it was "there." The 14.7 was pretty evident the
whole time.

I'm going to need to look again tonight, as those are both past the supposed
limiting visual magnitude of the aperture.

Will report back...

I have posted an image
which labels the stars in the immediate area of Messier 57 with their
magnitudes on my website.

To see the image, go to http://home.earthlink.net/~martinhowell and click
on "Other stuff"



rat
~( );

email: remove 'et' from .com(et) in above email address

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/

**********************************************
* Attend the 11th Annual NEBRASKA STAR PARTY *
* July 18-23, 2004, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
**********************************************

"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

On Tue, 7 Sep 2004 21:22:35 -0700, Jan Owen wrote:


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...


Hi Jan,

The central star continues to elude me. There have been a few occasions
when I could, if I were less demanding of my observations, claim to have
seen the star. . .but truth be told, apparently my timing is off. Clear
and moonless skies with really quality seeing conditions are tough to come
by up here in Lake Stevens. Reducing the odds even more is the fact that
for more than 8 years, I have worked a 10:00 p.m. to 6:00 a.m. shift with
an obligatory 2 nights off per week. However, my friend Tom Wales has
located a really dark location about 45 miles away and we may go there next
week and, if so, I'll give it another shot.


Martin

I think I got the 14.7 and the 15.3 opposite the mag 13, with the 8"
refractor.


OK, I went out again tonight. With a 9mm Nagler (200x) I got the 14.3, and
there is an unlabeled star opposite the 15.3 - I got it, too. I didn't get the
15.3, too faint. but the 14.1 down and to the left of the 13.0 was pretty easy.
It looks like I am limited to around mag 14.3, not bad for an 8"er.
rat
~( );

email: remove 'et' from .com(et) in above email address

"Martin R. Howell" writes:

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.

Thanks for posting the labeled image. I know you intended this
exercise to be visual but, as a result of some recent experiments with
balancing my homebuild 10" Newtonian on a Vixen GP-DX mount for CCD
imaging, I had this 60 sec unguided exposure of M57 to compare
with. My results: anything above mag 17 is glaringly obvious, the 17.3
star is still easy, while the 17.7 one cannot for sure be
distinguished from the background noise.

pej
--
Per Erik Jorde

Martin Howell wrote:
[snip] 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"

Here's a link to photometry for the field stars around M57:
http://c3po.cochise.cc.az.us/astro/deepsky02.htm

It was compiled by USNO's Arne Henden using the 1.0-meter at the observatory's
Flagstaff station. A link directly to Henden's data file is embedded within the
above page. Folks can check Martin's artwork against this and also add more
star magnitudes as needed.

I use the trio of faint stars that point at the western edge of the Ring to
determine if conditions are right for seeing the ~15.2 magnitude central star.
When these have been visible in my 10-inch, the central star has been visible
intermittently as the seeing steadies. The 15.6 magnitude star 40 arcseconds
south of M57 is another useful benchmark.

M57 central star observation with 10-inch:
http://members.aol.com/billferris/m57.html

Regards,
Bill Ferris
"Cosmic Voyage: The Online Resource for Amateur Astronomers"
URL: http://www.cosmic-voyage.net
=============
Email: Remove "ic" from .comic above to respond

Martin R. Howell wrote:

On Tue, 7 Sep 2004 21:22:35 -0700, Jan Owen wrote:

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...

Hi Jan,

The central star continues to elude me. There have been a few occasions
when I could, if I were less demanding of my observations, claim to have
seen the star. . .but truth be told, apparently my timing is off. Clear
and moonless skies with really quality seeing conditions are tough to come
by up here in Lake Stevens. Reducing the odds even more is the fact that
for more than 8 years, I have worked a 10:00 p.m. to 6:00 a.m. shift with
an obligatory 2 nights off per week. However, my friend Tom Wales has
located a really dark location about 45 miles away and we may go there next
week and, if so, I'll give it another shot.

Martin

I've seen it clearly, with direct vision. But, it was through the FPOA's
30" scope... :-) I guess I don't stand a chance with my own 8". :-(

- Alex