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Date: 16 Jul 2007 13:49:30
From: brucegooglegroups
Subject: finding the ring nebula
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I am trying to find the Ring nebula The distance between Sheliak and
the Ring seems to be 1 degree. How do I approximate this using a 4.5
Dob?
Thanks.
Bruce
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Date: 17 Jul 2007 19:24:56
From: Sam Wormley
Subject: Re: finding the ring nebula
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brucegooglegroups wrote:
> I am trying to find the Ring nebula The distance between Sheliak and
> the Ring seems to be 1 degree. How do I approximate this using a 4.5
> Dob?
Actually M57, Ring nebula, is about as easy as they come to find. If
you can see the two bottom bright stars which are fairly visible to
the unaided eye in moderately light polluted area. Center a Telrad
between them and you should have the ring in your field of view.
http://www.knoxvilleobservers.org/dsonline/tips/m57crt.html
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Date: 17 Jul 2007 18:30:27
From: brucegooglegroups
Subject: Re: finding the ring nebula
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On Jul 17, 4:38 am, Ernie Wright <ern...@comcast.net > wrote:
> brucegooglegroups wrote:
> > I am trying to find the Ring nebula The distance between Sheliak and
> > the Ring seems to be 1 degree. How do I approximate this using a 4.5
> > Dob?
>
> No one has mentioned this yet: You can estimate the field of view of an
> eyepiece with a pretty simple formula.
>
> Assuming you have the Orion SkyQuest 4.5-inch f/8 Dob, its focal length
> is 915mm, and it came with 25mm and 10mm Pl=F6ssl eyepieces, both of which
> have about a 50-degree *apparent* field of view. The magnification or
> power of the two eyepieces is
>
> 915 / 25 =3D 37x
> 915 / 10 =3D 92x
>
> The true field of view is the apparent field of view divided by the
> power.
>
> 50 / 37 =3D 1.4 degrees
> 50 / 92 =3D 0.5 degrees
>
> As a quick check, the Moon should fill the view in the 10mm eyepiece,
> while the view in the 25mm eyepiece will be about three Moons wide.
>
> So with the lower power 25mm eyepiece, you should be able to see both
> beta Lyrae (Sheliak) and M57 (the Ring Nebula) at the same time.
>
> But don't underestimate how difficult it will be for you to pick out the
> Ring at first. Although experienced observers describe it as bright and
> easy to find, it is neither when you're starting out. It'll look like a
> faint, out-of-focus star at low power, and you may not notice anything
> unusual about it.
>
> M57 was the first deep-sky object I looked for when I got my 8-inch Dob
> 10 years ago, and I think it took me 20 minutes to find it. I'm sure I
> scanned past it many times before I recognized it. (I can find it
> instantly in a 3-inch refractor now.)
>
> - Ernie http://home.comcast.net/~erniew
Thanks all for the suggestions.
Ernie- I appreciate your explaining how difficult it is find the ring
at the beginning.
The FOV is very important. I didn't realize that the Ring and Beta
Lyrae would fit into the same view. So it seems that I won't be able
to see the Ring Structure at low power- but it will look more like a
star... Where will it be in the eyepiece in relation to Beta Lyrae-
will it be on the Northern(bottom) part of the view?
Bruce
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Date: 17 Jul 2007 23:51:04
From: Ernie Wright
Subject: Re: finding the ring nebula
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brucegooglegroups wrote:
> Ernie- I appreciate your explaining how difficult it is find the ring
> at the beginning.
> The FOV is very important. I didn't realize that the Ring and Beta
> Lyrae would fit into the same view. So it seems that I won't be able
> to see the Ring Structure at low power- but it will look more like a
> star...
Like an out-of-focus star. A very small, ghostly, circular patch.
I located it tonight. No mean feat--there's a high haze where I am
(central Maryland), and the only two stars I can see naked eye are Vega
and Arcturus, so I had to star hop just to find beta Lyrae. I used a
32mm Televue Plössl in my 8-inch f/6 Dob, which should give the exact
same magnification and field of view as your 25mm.
Given the conditions, it was at the very edge of detectability in the
32mm. I could see it a little better in the 15mm.
> Where will it be in the eyepiece in relation to Beta Lyrae-
> will it be on the Northern(bottom) part of the view?
No, more like eastward and (probably) toward the top. The latter will
depend on what time you look.
Directions can get confusing. North on the celestial sphere is the
direction toward Polaris, and east is in the direction of increasing
right ascension. In a Dob, the view is upside-down, but also rotated to
some extent, how much depending on the position of the focuser and on
how your brain perceives your orientation when you're looking through
it.
But as it happens, at about 11 PM local (daylight saving) time right
now, beta and gamma Lyrae, and M57, are on an almost perfectly vertical
line. If you center beta, then move the tube *down* about half the
field of view, M57 should be pretty nearly centered.
Also keep in mind, conditions can strongly affect the visibility of
extended objects like M57. If you're looking in humid, hazy, not-
really-dark conditions, even something considered bright and easy will
be tough, especially in smaller apertures.
- Ernie http://home.comcast.net/~erniew
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Date: 17 Jul 2007 04:55:19
From: Ben
Subject: Re: finding the ring nebula
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There's a chain of 9th mag stars between Beta and Gamma Lyrae.
Scan that chain untill you find a 9th mag star that looks "frumpy"
and then turn up the power on it.
Ben
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Date: 17 Jul 2007 04:38:42
From: Ernie Wright
Subject: Re: finding the ring nebula
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brucegooglegroups wrote:
> I am trying to find the Ring nebula The distance between Sheliak and
> the Ring seems to be 1 degree. How do I approximate this using a 4.5
> Dob?
No one has mentioned this yet: You can estimate the field of view of an
eyepiece with a pretty simple formula.
Assuming you have the Orion SkyQuest 4.5-inch f/8 Dob, its focal length
is 915mm, and it came with 25mm and 10mm Plössl eyepieces, both of which
have about a 50-degree *apparent* field of view. The magnification or
power of the two eyepieces is
915 / 25 = 37x
915 / 10 = 92x
The true field of view is the apparent field of view divided by the
power.
50 / 37 = 1.4 degrees
50 / 92 = 0.5 degrees
As a quick check, the Moon should fill the view in the 10mm eyepiece,
while the view in the 25mm eyepiece will be about three Moons wide.
So with the lower power 25mm eyepiece, you should be able to see both
beta Lyrae (Sheliak) and M57 (the Ring Nebula) at the same time.
But don't underestimate how difficult it will be for you to pick out the
Ring at first. Although experienced observers describe it as bright and
easy to find, it is neither when you're starting out. It'll look like a
faint, out-of-focus star at low power, and you may not notice anything
unusual about it.
M57 was the first deep-sky object I looked for when I got my 8-inch Dob
10 years ago, and I think it took me 20 minutes to find it. I'm sure I
scanned past it many times before I recognized it. (I can find it
instantly in a 3-inch refractor now.)
- Ernie http://home.comcast.net/~erniew
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Date: 16 Jul 2007 22:26:09
From: brucegooglegroups
Subject: Re: finding the ring nebula
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On Jul 16, 5:18 pm, Chris L Peterson <c...@alumni.caltech.edu > wrote:
> On Mon, 16 Jul 2007 13:49:30 -0700, brucegooglegroups
>
> <brucegooglegro...@hotmail.com> wrote:
> >I am trying to find the Ring nebula The distance between Sheliak and
> >the Ring seems to be 1 degree. How do I approximate this using a 4.5
> >Dob?
>
> Hi Bruce-
>
> I'm not a starhopper, so I'll leave it to others to give you some advice
> on methods of estimating distance and angle. But the Ring is one of the
> easiest objects to find, and is bright enough to see under almost any
> kind of skies. You should easily be able to move your scope back and
> forth between the two southern parallelogram stars of Lyra, Sheliak and
> Sulafat (the pair farthest from Vega). The Ring sits almost directly
> between the two. Start with your lowest magnification. It may first
> appear (especially at low magnification) as a sort of fuzzy star, but
> closer examination should show its ring structure, unless your skies are
> very bright.
>
> _________________________________________________
>
> Chris L Peterson
> Cloudbait Observatoryhttp://www.cloudbait.com
Hi All,
Thanks for your replies. I have been learning the constellations this
year, and I am trying to do more deep sky. The question is- am I
moving the telescope too much to find The ring?
I know where it is located. With the Dob, I haven't been looking at
the top of the view coming from Sheliak,( south) so perhaps I didn't
see it.
Bruce
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Date: 16 Jul 2007 19:08:20
From: Joe S.
Subject: Re: finding the ring nebula
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"brucegooglegroups" <brucegooglegroups@hotmail.com > wrote in message
news:1184624769.042645.37760@q75g2000hsh.googlegroups.com...
> On Jul 16, 5:18 pm, Chris L Peterson <c...@alumni.caltech.edu> wrote:
>> On Mon, 16 Jul 2007 13:49:30 -0700, brucegooglegroups
>>
>> <brucegooglegro...@hotmail.com> wrote:
>> >I am trying to find the Ring nebula The distance between Sheliak and
>> >the Ring seems to be 1 degree. How do I approximate this using a 4.5
>> >Dob?
>>
>> Hi Bruce-
>>
>> I'm not a starhopper, so I'll leave it to others to give you some advice
>> on methods of estimating distance and angle. But the Ring is one of the
>> easiest objects to find, and is bright enough to see under almost any
>> kind of skies. You should easily be able to move your scope back and
>> forth between the two southern parallelogram stars of Lyra, Sheliak and
>> Sulafat (the pair farthest from Vega). The Ring sits almost directly
>> between the two. Start with your lowest magnification. It may first
>> appear (especially at low magnification) as a sort of fuzzy star, but
>> closer examination should show its ring structure, unless your skies are
>> very bright.
>>
>> _________________________________________________
>>
>> Chris L Peterson
>> Cloudbait Observatoryhttp://www.cloudbait.com
>
> Hi All,
> Thanks for your replies. I have been learning the constellations this
> year, and I am trying to do more deep sky. The question is- am I
> moving the telescope too much to find The ring?
> I know where it is located. With the Dob, I haven't been looking at
> the top of the view coming from Sheliak,( south) so perhaps I didn't
> see it.
>
> Bruce
>
As others have suggested, start with your lowest power eyepiece. My lowest
power is a TeleVue 35mm Panoptic. On my scope, with 1500mm focal length,
that gives me 43X. At that magnification, Sheliak and Sulafat are on the
top and bottom edge of my FOV (well, one or the other is on the top or
bottom and the other is just barely out of the FOV) and the Ring is in the
middle. HOWEVER -- at 43X, the ring is TINY. It's a tiny, fuzzy thing that
upon further viewing appears perfectly round -- but -- it's still tiny.
One trick is to move the eyepiece slowly in and out of focus. The stars
will become fuzzy as they go out of focus, but, because the Ring is already
a faint fuzzy object, it will seem not to go out of focus.
When you think you have found the Ring, pop in a more powerful eyepiece -- I
go to an 18mm Radian at 83X and at that point the Ring starts to look like a
ring. At over 100X, the star in the center is obvious and the Ring is
clearly a ring.
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Date: 16 Jul 2007 22:07:33
From: Marty
Subject: Re: finding the ring nebula
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As others have pointed out, the ring will be pretty dinky in your low
power eyepiece, which is the best one to do your starhopping with. You
may well have seen it, thinking it was a star. Once you think you might
have it in your field of view, pop in the next higher power eyepiece,
and see if the "ring shape" or a tiny oval starts to appear.
This will all get easier the more you do it. Hang in there.
Marty
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Date: 16 Jul 2007 23:39:51
From: OG
Subject: Re: finding the ring nebula
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"brucegooglegroups" <brucegooglegroups@hotmail.com > wrote in message
news:1184624769.042645.37760@q75g2000hsh.googlegroups.com...
> On Jul 16, 5:18 pm, Chris L Peterson <c...@alumni.caltech.edu> wrote:
>> On Mon, 16 Jul 2007 13:49:30 -0700, brucegooglegroups
>>
>> <brucegooglegro...@hotmail.com> wrote:
>> >I am trying to find the Ring nebula The distance between Sheliak and
>> >the Ring seems to be 1 degree. How do I approximate this using a 4.5
>> >Dob?
>>
>> Hi Bruce-
>>
>> I'm not a starhopper, so I'll leave it to others to give you some advice
>> on methods of estimating distance and angle. But the Ring is one of the
>> easiest objects to find, and is bright enough to see under almost any
>> kind of skies. You should easily be able to move your scope back and
>> forth between the two southern parallelogram stars of Lyra, Sheliak and
>> Sulafat (the pair farthest from Vega). The Ring sits almost directly
>> between the two. Start with your lowest magnification. It may first
>> appear (especially at low magnification) as a sort of fuzzy star, but
>> closer examination should show its ring structure, unless your skies are
>> very bright.
>>
>> _________________________________________________
>>
>> Chris L Peterson
>> Cloudbait Observatoryhttp://www.cloudbait.com
>
> Hi All,
> Thanks for your replies. I have been learning the constellations this
> year, and I am trying to do more deep sky. The question is- am I
> moving the telescope too much to find The ring?
> I know where it is located. With the Dob, I haven't been looking at
> the top of the view coming from Sheliak,( south) so perhaps I didn't
> see it.
>
> Bruce
I'd recommend starting with your very lowest magnification eyepiece so that
you can see Beta and Gamma Lyrae in the field of view. If you can't get them
both in view at the same time, move the scope around so that both stars are
about the same amount 'out' of view.
Then pop in a middling power eyepiece and the Ring should be somewhere near
the centre of the FOV. Two tricks can help pick it out from the other stars
. . .
Adjust the focus just either side of 'sharp' - stars will vary in
appearance, but the ring (being an extended object) will show less obvious
change as you adjust the focus.
If that doesn't work, get your focus as sharp as possible and give the scope
a little tap, just enough to jiggle the stars in the eyepiece. I don't know
about anyone else, but my eye/brain can pick out a clear difference how the
motion is in perceived for point objects and extended objects.
Once you've pinned it, get it centred and move to a higher power eyepiece.
The latter is also useful for faint extended objects.
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Date: 16 Jul 2007 21:18:59
From: Chris L Peterson
Subject: Re: finding the ring nebula
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On Mon, 16 Jul 2007 13:49:30 -0700, brucegooglegroups
<brucegooglegroups@hotmail.com > wrote:
>I am trying to find the Ring nebula The distance between Sheliak and
>the Ring seems to be 1 degree. How do I approximate this using a 4.5
>Dob?
Hi Bruce-
I'm not a starhopper, so I'll leave it to others to give you some advice
on methods of estimating distance and angle. But the Ring is one of the
easiest objects to find, and is bright enough to see under almost any
kind of skies. You should easily be able to move your scope back and
forth between the two southern parallelogram stars of Lyra, Sheliak and
Sulafat (the pair farthest from Vega). The Ring sits almost directly
between the two. Start with your lowest magnification. It may first
appear (especially at low magnification) as a sort of fuzzy star, but
closer examination should show its ring structure, unless your skies are
very bright.
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
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Date: 16 Jul 2007 21:14:12
From:
Subject: Re: finding the ring nebula
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On Jul 16, 1:49 pm, brucegooglegroups <brucegooglegro...@hotmail.com >
wrote:
> I am trying to find the Ring nebula The distance between Sheliak and
> the Ring seems to be 1 degree. How do I approximate this using a 4.5
> Dob?
Here's some practical advice. During daylight hours enlist a friend to
hold a confectioner's powdered sugar coated doughnut against a
cooperating neighbor's exterior house wall which you painted flat
black. This kindly neighbor should live between 300 and 400 feet from
your scope and that newly painted black wall should be clearly in
sight. Now, with your daylight adapted eyes, center that doughnut in
your telescope's finder device and peer through the eyepiece of your
telescope. Look at the doughnut. Study it carefully. Take an afocal
photo or two of it if you are so moved. Eat the doughnut. Then, when
night falls, direct the telescope to the area between Beta Lyrae and
Gamma Lyrae and slowly sweep the region until you see something that
looks familiar. Voila!! Messier 57.
--
Martin R. Howell
Moderated sci.astro.amateur
www.moderatedsciastroamateur.org
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Date: 16 Jul 2007 23:59:08
From: I.N. Galidakis
Subject: Re: finding the ring nebula
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brucegooglegroups wrote:
> I am trying to find the Ring nebula The distance between Sheliak and
> the Ring seems to be 1 degree. How do I approximate this using a 4.5
> Dob?
> Thanks.
Just point your finder exactly to the middle of the line joining Sheliak and
Sulafat. Using low magnification (25-35x) the ring should fall right in your
field of view.
> Bruce
--
I.N. Galidakis --- http://ioannis.virtualcomposer2000.com/
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