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NGC 6572 - weird

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#1 astro4565

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Posted 31 October 2013 - 05:01 PM

Anybody observe NGC 6572 in Ophuichus? I observed it last Saturday night and it seemed to be pulsating back and forth in brightness.It was like an irregular variable star with a greenish hue.

#2 EJN

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Posted 31 October 2013 - 06:51 PM

What you probably saw was the "blinking" effect when you move your eye, like
NGC 6826, the "blinking" planetary in Cygnus, the most well known example.

#3 Bill Weir

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Posted 31 October 2013 - 08:52 PM

It's not really the best time of the year to be observing this little planetary. How high in the sky was it when you observed it? I know I'm further north than you but by this time of the year it's alot closer to the SW horizon. I'm guessing atmospheric distortion coupled with poor seeing created the pulsation effect. Next year when NGC 6572 is higher in the sky, close to the meridian observe it and I think you won't see the pulsing.

This is what I think. Besides that, NGC 6572 is a fabulous onject to observe. The colour is beautiful.

Bill

#4 youngamateur42

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Posted 31 October 2013 - 09:51 PM

I saw this planetary last year with my dad's XX14g from a red zone. It was very green colored, with a relatively bright central star, easy with direct vision. Very cool object, but very small and the color makes it really stand out. Steve Coe has a sketch of this object, he'll probably chime in here

#5 astro4565

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Posted 31 October 2013 - 10:53 PM

I wondered if it was atmospheric distortion. Normally, I view this object in the summer when it is higher but we had an early monsoon season this summer and rain in September so I was late observing this object. In 2003, I viewed this object with the Lowell Observatory 24" refractor and have been hooked on this planetary ever since.

It has never had a blinking effect. I think you get that with smaller aperature. I used my 15" Obsession telescope.

Next year, I'm going up to an 8000 foot observing site before the monsoon season.

#6 IVM

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Posted 01 November 2013 - 10:19 AM

I saw it with my 7" and 16" scopes and did not notice any blinking effect. The blue color was beautiful and bright though.

#7 astro4565

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Posted 01 November 2013 - 10:26 AM

You saw that as blue? It looked deep green to me. NGC 6543 looked turquoise and NGC 7662 was definitely blue. I guess that is why viewing planetary nebulae is so interesting.

#8 IVM

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Posted 01 November 2013 - 12:48 PM

I noticed the difference between our descriptions. It seems to be common though that the perception of the typical planetary nebula color (around 500 nm wavelength, i.e. technically turquoise) is individual and depends on the specific planetary as well. This one was distinctly blue to me, but I do see some other planetaries as green. Although the saturation does, the hue of a specific planetary for me does not seem to depend on aperture or magnification.

#9 stevecoe

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Posted 01 November 2013 - 02:23 PM

Howdy all;

Here is an observation with my old 13 inch Newtonian.

NGC 6572 13" f/5.6 Cherry Rd Seeing=6, Transparency=7 Bright, pretty large, elongated 1.5X1 in PA 135 using 220X. The central star is held steady in good seeing conditions. Other times the center will just brighten up somewhat. The noteworthy aspect of this gem is its' color. In every scope I have ever owned, from an 8" to an 18" this is the greenest nebula I have ever seen! This guy is as green as an Irishman's coat on St. Patrick's day. Alright, alright, it is as green as lime Jello.

Clear skies;
Steve Coe

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#10 Keith Rivich

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Posted 09 November 2013 - 11:29 AM

Great discussion! Years ago we nicknamed 6572 the "blue racquetball" due to its resemblance to its bigger cousin 7662. As you can imagine this started a big debate as some of saw it as green and others as blue, with a few in betweens thrown in.
On a clear night with 6572 overhead we did an experiment with 30 or so college kids that came out for a night of observing. Using a 12.5 f/5 we asked the group to look at the planetary and note it's color, but not to reveal their observation. After all were through they wrote done the color they saw. Of the 30, 20 saw it as greenish and 10 bluish. Most interesting of all is all of the girls (8) we're in the blue!

I see as bright green at low power and slightly more blue at higher powers. Interesting little object, this is why I do astronomy!

#11 uwe_glahn

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Posted 09 November 2013 - 12:13 PM

The color perception at this PN is very different. I remember back when I saw this PN cyan to green with a 20" Dob. A month later we tried it with a 10" SC under bad conditions and all 6 observers saw the PN in a light blue. Don't ask me why. Later I revisit the PN with my 27" and a saw it again intensive cyan to green, even with 586x (AP 1,2mm).

But I never saw the CS, even not with 27" under nearly perfect conditions (transparency and seeing). You can easily mix up the "false CS" with the very bright center of the PN.

27", 837x, no filter, NELM 7m+, Seeing II
Posted Image
inverted version

#12 Sasa

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Posted 09 November 2013 - 02:42 PM

NGC6572 is very nice planetary, interesting even in small telescopes:

Posted Image

Never noticed blinking on this planetary either.

#13 Asbytec

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Posted 09 November 2013 - 10:03 PM

Alex, amazing. I'm getting that itch, again. Where's Pete?

#14 azure1961p

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Posted 10 November 2013 - 09:32 AM

I'll take a look at this next year as its too low in the west at nightfall to see with any clarity. Looks like a nice one - just to low for now. I believe this one is in my list of bright shall summer planetaries. The OP no doubt was seeing the scintillation effects of low altitude on a small object.



Pete

#15 sgottlieb

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Posted 07 December 2013 - 02:35 AM

The color perception at this PN is very different. I remember back when I saw this PN cyan to green with a 20" Dob. A month later we tried it with a 10" SC under bad conditions and all 6 observers saw the PN in a light blue. Don't ask me why. Later I revisit the PN with my 27" and a saw it again intensive cyan to green, even with 586x (AP 1,2mm).


Uwe, I've noted this color change also, and in the same observation!

18" (8/2/05): at 225x I noticed an interesting color effect; although the color was a quite prominent bluish-green, while staring at the center the planetary decreased in size and the color changed to a deep emerald green.






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