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Cosmic Challenge: Ring Nebula Central Star and Galaxy IC 1296

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#1 PhilH

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Posted 01 September 2020 - 05:08 AM

As we say goodbye to summer and get ready to welcome in autumn, I thought I would offer not one, but two challenges this month to bridge the seasonal change. Both appear right next to each other in our sky but are millions of light years apart. And both require all the aperture you can throw at them to be seen.

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#2 MikiSJ

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Posted 01 September 2020 - 07:19 PM

I once viewed the Ring, on a moonless night, through the Great Lick Refractor, a 36" doublet. Even with the huge aperture and knowing what I was trying to see the central star eluded me and the two fellow astronomers I was with at the time.

 

IMO, with most amateur kits, visually see seeing the central star is not going to happen.


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#3 KTAZ

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Posted 01 September 2020 - 07:34 PM

I viewed this little gem from a dark sky site (B3) in June with my C9.25. My notes from that nights session:

 

"Rapidly becoming one of my favorites. In the 40mm it's just a little ring, but is clearly a star that has blown off it's hydrogen layer. Nice view in the 25mm, but degrades with the 13.8. Neither eyepiece would reveal the central star." 

 

And believe me, I looked for it!


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#4 David Knisely

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Posted 01 September 2020 - 10:27 PM

 I guess this item has popped up yet again when talking about the potentially "difficult".  The Central Star of M57 is visible in instruments *smaller* than 15 to 18 inches, but it requires certain conditions be met (and not necessarily the darkest skies are needed).  The star itself is around magnitude 15.2, which, under outstanding conditions might be reachable in an eight inch scope (although with many things astronomical, the larger the aperture, the better).  The smallest aperture I have seen the central star in was my 9.25 inch SCT, although it was pretty marginal in that instrument.  I recall my first serious attempt to see the central star in a truly large scope when I was an undergraduate at the University of Nebraska using their 30 inch Classical Cassegrain at Behlen Observatory near Mead, Nebraska.  I had previously failed to see it in 10 and 12.5 inch scopes during some of our club star parties over the years, so I thought that the 30 inch should do the trick, if seeing the darn thing was possible at all.  When I got my turn at the big scope, I didn't see the star, and mentioned it aloud in the dome to Dr. Don Taylor, who was running the scope at the time.  Taylor stated bluntly that he hadn't even seen it in the 90 inch at Steward Observatory on Kitt Peak!  From that point on, I considered the star a virtual impossibility in any amateur instrument.  Claims made by smaller apertures I also considered "illusions" caused by the glowing interior of the Ring, which at low power can induce a sort of "false" central star effect (one reason I discount observations of the star at powers much under 300x).

 

However, years later, I was proven quite wrong one evening at our club observing site (Zenith Limiting Magnitude 6.6 or so).  One of our new members had moved up from Texas, and had a new 20 inch f/5 Obsession.  He mentioned about having the central star in his scope, so like a skeptic, I went up the ladder to take a look in and disprove what he was claiming.  He was running some ridiculous power well over 400x, but what I saw just stunned me and also quickly solved the mystery.  The central star was quite prominently visible with direct vision for a number of seconds, but suddenly, it winked out, as if someone had just shut the darn thing off with a switch!  Then, a few moments later, it reappeared at its full brightness just as suddenly as it had vanished.  It kept up this perplexing "flashing" behavior for a while until I noticed that the diffraction disk of the 13th magnitude star east of the Ring got bigger and more diffuse when the star was not visible, but shrunk down to its tiny disk when the star popped out.  I also saw it in a nearby Sky Designs 17.5 inch, and the central star behaved in exactly the same way.  It was not visible at powers much under 300x, but once the power got high enough, it was not all that difficult.  The higher magnification may serve to help reduce the effects of the glowing center, but if the seeing is less than perfect, the star's diffraction disk will blur to a point where it completely blends into the glowing background nebulosity.  If seeing is not first rate or the power isn't high enough, you will *never* see the central star in ANY aperture.  You also have to often watch for quite a while and wait for those brief moments when the seeing settles down enough to make the star visible.  Once I understood that, after a number of tries, I succeeded in sighting the star in my 10 inch f/5.6 Newtonian, although again, often it appears faintly only for a few brief moment before vanishing.  One night, I had been working double stars from my mildly light polluted (ZLM 5.4) driveway in my town of 12,800, and was using my 9.25 inch SCT at some pretty high powers (my 5-8mm Speers Waler at the 5mm setting, or about 470x)  I had forgotten to replace that eyepiece with a lower power one and just commanded the NexStar 9.25 to go to M57 just for a final look at the end of the observing session.  Once the slew was completed, I took a look in and was astounded.  There, right in the middle of the ring was the faint glimmer of the central star, just shining there steadily with averted vision.  After a couple of seconds, the "star" must have sensed I was looking at it and it must have said to itself, "I have been SEEN!", whereupon, it promptly vanished :-).  I watched for quite a while after that, and once or twice, I saw it come on and then almost instantly go out, but it was never visible for much more than half a second or so.  Again, observing at high power (more than 300x) and observing the nebula for and extended period of time to catch those moments when the seeing becomes really stable are the keys to success in viewing M57's central star.

 

As for IC 1296, the first time I saw it was at the Nebraska Star Party in Dave Hamilton's 12 inch Portaball, but all I can get of it in my 10 inch Newtonian is just a hint of a fuzzy patch.  In a 24 inch Obsession however, it was full of faint but easily visible spiral structure at high power.  Clear skies to you.


Edited by David Knisely, 02 September 2020 - 02:29 AM.

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#5 Special Ed

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Posted 02 September 2020 - 08:53 AM

Phil,

 

Great challenge for folks to try.  waytogo.gif   I can confirm what David said above.  I looked for the central star with my C14 at 261x under good seeing conditions and transparency and with M57 almost at the zenith and could not detect the central star.  The Ring Nebula looked like this:

 

https://www.cloudyni...0-m57-20100831/

 

Three nights later, with the same scope and conditions but using 391x, this time I detected the central star:

 

https://www.cloudyni...1-m57-20100902/

 

I didn't know to look for IC 1296 but I will next time!  Thanks, Phil.  smile.gif


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#6 wargrafix

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Posted 02 September 2020 - 01:06 PM

I have seen it pretty definitively with my C9.25.

 

Conditions were excellent transparency (No Saharan Dust). While my location is bortle 6, to my west is very dark skies.

 

It was during rainy season so the seeing was particularly excellent. The central star was very apparent. I had to use averted vision at times. No luck with the galaxy on visual.


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#7 Achernar

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Posted 02 September 2020 - 04:47 PM

I have seen the central star a couple of times with my 15-inch Dob, and even a 10-inch Dob once under skies that were hardly ideal thanks to light pollution and the haze that hangs over the Gulf Coast. However, the seeing became very steady, and when it's gets very steady, the star became remarkably easy to see when the magnification's high enough. When it declined, the star vanished as though it never was there. I have looked for IC-1296, and only suspected that I spotted it once.

 

Taras


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#8 John O'Hara

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Posted 06 September 2020 - 06:56 AM

I confess to never having seen it in any of my scopes, which top out at 12.5", but I've not tried with really high magnification under good seeing.  Where I live, in Northwestern Pennsylvania, we're so often under the jet stream.  I've always been intrigued that Walter Scott Houston wrote that the 12" Porter Turret telescope at Stellafane often showed it when larger scopes failed.

 

I'm heading up to Cherry Springs State Park in Pennsylvania on 9/11 and staying until 9/20.  Maybe one of those nights will cooperate.


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#9 Astro-Master

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Posted 06 September 2020 - 04:48 PM

I've seen the central star many times in my 18" Obsession at 350x or more, and believe good seeing is more important than transparency or a dark sky.  It goes without saying that observing it when its near the meridian will help.

 

When you can see the 16th magnitude star just west of the ring nebula at 300x or more you have a chance to see the central star.  Most of the time you'll get few pops for a split second, its like its winking at you.  

 

On the nights when the seeing gets really good I've used 1,000x, and the central star becomes visible with direct vision for several seconds.

 

Once when helping my friend set up his servo-cat drive on his 20" Obsession in his back yard in the city, (Bortle 7 zone) we wanted to test his drive with high power. 

 

M57 was high overhead, the transparency was average, but the seeing that night was extraordinary.  I used my TV 3-6mm zoom and at 3mm, (846x) the central star was visible.  My friend wanted to test the drive at extreme power, so I used my TV Big Barlow and an extension tube between the barlow and the 3-6 zoom for a power of around 2,100x.

 

I almost fell off the ladder, there were two stars visible, the central star and a slightly fainter star nearby.  Both stars were visible 100% of the time with direct vision, it was an amazing site I'll never forget.


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#10 Phillip Creed

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Posted 11 September 2020 - 02:47 PM

IC 1296 is a good visual challenge being easy to locate but hard to detect.  I've gotten it with an 8" reflector under Bortle Class 4 skies that was flocked to maximize contrast.  Everything had to come together--clean mirror, clean eyepieces, good transparency, dark sky and I used an observing hood.

Best reserved for larger apertures, yes, but it was one of those "not that I SHOULD, but wondering if I COULD" kind of deals on the nights I went for it.

Clear Skies,
Phil


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#11 pbealo

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Posted 12 September 2020 - 09:22 AM

Phil,

Just thinking about your points on transparency and sky brightness.

 

Some years ago I did some reading and research on "Concurrent Photon Amplification" in silver halide photography. See: https://apps.dtic.mi...s/ADA151831.pdf . I am wondering if the eye works similarly (though non-integrating!), Do all the photons need to come from the star? Can some from background sky brightness boost the total sufficiently to allow the star to be seen?


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#12 Achernar

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Posted 20 September 2020 - 06:13 PM

IC 1296 is a good visual challenge being easy to locate but hard to detect.  I've gotten it with an 8" reflector under Bortle Class 4 skies that was flocked to maximize contrast.  Everything had to come together--clean mirror, clean eyepieces, good transparency, dark sky and I used an observing hood.

Best reserved for larger apertures, yes, but it was one of those "not that I SHOULD, but wondering if I COULD" kind of deals on the nights I went for it.

Clear Skies,
Phil

You succeeded where I failed with a telescope with almost twice the aperture, and thus seeing IC-1296 with an 8-inch is a real accomplishment.

 

Taras


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