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Planetary Nebulae in a small scope


AndyWB
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Okay, so I'm a little puzzled by a couple of planetary nebulae - specifically, the Blinking Planetary (NGC 6826) and Cat's Eye Nebula (NGC 6543). I'm not entirely clear what I should expect to see in a 130mm scope.

I think that I've seen them; both seemed to be small discs of a kind of electric blue/green colour. I didn't get the blinking from the Blinking planetary, but it was pretty dark where I was. I did get the blinking effect previously on the Cat's Eye Nebula, though, under a moonlit sky. Both looked ... round. I didn't see any shells or anything.

I'm just a little puzzled, as images of these (and, indeed, lots of other planetaries) seem to have complex structures, and some of those (e.g. the Ring Nebula, or Dumbbell Nebula) are pretty visible. I understand that images of them will show vastly more detail, but Googling for sketches of these two seems to show more structure than I've seen, though with significantly larger scopes.

So I guess the question is, what should I expect to see of these in my scope? And is this a case of needing more aperture to pull out more detail than the disc-like appearance? Or have I actually seen something completely different? (That wouldn't be the first time!)

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Aperture is king ! You'll find the most glorious pictures of nebulae by Hubble. Visually you'll see the fluff of diffuse planetaries like M27 and M76, the ring of M57 and the blinking effect and blue colour of the disc like planetaries.

I've come to call the cat's eye, the cat's tiny fluff ball.

Really depends how you use your vision, I look either to one side or above then directly back to see the target briefly disappear.

I've seen this effect at x48, however good seeing conditions do help.

Basically at low magnification you're looking for anything non stellar. For instance at x48 Uranus is presently a non sparkling disc.

Have a shot at the Blue Snowball NGC 7662, well placed above Pegasus and just a stunning blue snowball. You'll then know what to expect !

Nick.

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Whilst some planetary nebulae are reasonable in size (M27 springs to mind) most are tiny. The blue snowball appears little bigger than a fuzzy (but beautifully blue) star, with the likes of M27 being little bigger at all. Try upping the power of your EPs to your 8 and 5mm BSTs... planetary nebs' stand up very well to high magnification.

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I've a telescope about your size and yes i've seen 6826 'blink' - it's like it disappears and appears with averted vision. Other than the showpiece ones - hardly more than stellar in a small scope in magnification below 50x. Fascinating things.

I can't remember which one it's either the Blue Snowball or Eskimo Nebula which are completely star like but when you hit about 90x suddenly jump out at you !

andrew

Edited by andrew63
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Okay, sounds like many of these are smaller than I'd realised - and that I might need to push the magnification a bit more. I think I'd expected something more obviously non-stellar at low magnification. I guess I'll have to revisit them!

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NGC 6543 is quite small even in 12'' Dob, you really need proper dark skies to be able to see more detail on high magnification.

Well, that's reassuring. I think I was getting confused because they are so small. One of the things I've learnt since I started this in March are that magnification is usually unimportant (except in some special cases), so I maybe didn't push the magnification enough.

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I found M27 for the first time recently having noticed it on the star map but never gone after it.

It's surprising how much it shows I thought, that was on a 6". I was even more surprised when I pointed the 14" at it. I'd never seen a picture of it before so didn't know what to expect. The name in my star atlas read 'Dumbell nebula' but what I saw was a large white puff fuzz with what looked like a darkened X in it. When I later looked it up on google I realised the dark X i saw was actually the dumbell effect for which the nebula has it's name and was pleased I managed to see this effect visually

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I saw M27 last night and even in the 5 inch scope ( same one as AndyW) I could make out a tiny little bit of detail ( no filters ) , I forgot what mag it was, whether I pushed it to the 8 or 15mm eyepiece, but I was stoked checking the attached picture afterwards I realised what I actually saw, it was the structure shown in red in that picture. The first time I ever saw that. Skies must be getting better :)

250px-M27_-_Dumbbell_Nebula.jpg

I've not been after many others so far, I would really need a better dark site I guess to chase the smaller ones, though had some very decent views of M57 too from my garden seeing the ring quite clearly.

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Well, that's reassuring. I think I was getting confused because they are so small. One of the things I've learnt since I started this in March are that magnification is usually unimportant (except in some special cases), so I maybe didn't push the magnification enough.

From my experience with planets, yes, magnification is not that important, but with small DSOs try to push as much magnification as you can until the view is nice and sharp.

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Planetary nebulae can be tough in small apertures because of the amount of power needed to resolve most of them well enough to be seen well.

There are a few large planetaries like the dumbbell, but on the whole, most are small.

This means most need high power to be seen well, smaller scopes struggle for light as we up the power, often resolution can come into it too., as many appear stellar in even quite substantial apertures.

I tend to check out planetaries details before hunting for them, paying careful attention to their size and mag.

Good hunting and clear skies :)

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