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Cosmic Challenge: IC 5217, the Little Saturn Nebula


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Cosmic Challenge:
IC 5217, the Little Saturn Nebula

 

September 2022

Phil Harrington

This month's suggested aperture range:

6- to 9.25-inch (15-24 cm) telescopes

 

 

 

Target

Type

RA

DEC

Constellation

Magnitude

Size

IC 5217

Planetary nebula

22h 23.9m

+50° 58.0'

Lacerta

11.3

7"

 

 

As we transition from summer to autumn, let's try our luck with a taxing planetary nebula in an equally taxing constellation. IC 5217 lies among the faint stars of Lacerta the Lizard. Locating the nebula is a big part of the challenge because of its dim surroundings.

 

Its dimness and remote position likely led to the Herschels missing it as they surveyed the skies. It evaded detection until Williamina Fleming discovered it in 1904 while examining stellar emission line spectrum on a photographic plate taken at Harvard College Observatory.

 

 

Above: Late evening star map showing the location of this month's Cosmic Challenge.

 

Credit: Map adapted from Star Watch by Phil Harrington

 

Above: Finder chart for this month's Cosmic Challenge.

 

Credit: Chart adapted from Cosmic Challenge by Phil Harrington
Click on the chart to open a printable PDF version in a new window

 

 

To spot IC 5217, use a technique offered many years ago by Walter Scott Houston in his Deep-Sky Wonders column. Begin by finding a four-star keystone asterism formed by Alpha (α), Beta (β), and 4 Lacertae, as well as 5.4-magnitude SAO 34143, about 18° east-northeast of Deneb [Alpha (α) Cygni]. The keystone measures about 3° across, small enough to fit into just about any finderscope. IC 5217 is located slightly northeast of the center of the keystone, in the same low-power field as the very red 6.5-magnitude star SAO 34425. The planetary is nestled just 3' west of a slender isosceles triangle of 11th- and 12th-magnitude stars.

 

Since IC 5217 shines only at magnitude 11.3 and measures just 7 arc-seconds across, an eyepiece switch will be needed to pick it out once its field is centered in view. Through my 6-inch Schmidt-Cassegrain telescope at 96x, the planetary was disguised as a star-like point. Increasing magnification to 240x, however, expanded the nebula's disk enough to identify it positively from the surrounding field. It appears grayish at this aperture and round. Try blinking the field with an O-III filter to enhance the nebula's disk.

 

Above: Sketch of IC 5217 as seen through the author's 6-inch (15-cm) Schmidt-Cassegrain at 240x.

 

The planetary takes on a faint bluish tint through 12-inch and larger telescopes. But there is little hope of seeing the central star since it shines at magnitude 15.5. In fact, the central star remains unseen through even the largest amateur telescopes because of the nebula's brightness. At magnifications around 400x or higher, those same instruments, however, hint at this planetary's bipolar structure. Some describe it as a Figure 8.

 

IC 5127 is nicknamed the Little Saturn Nebula owing to its resemblance to the Saturn Nebula (NGC 7009) in Aquarius, when viewed through the largest backyard instruments and crazy high magnification. With steady seeing and viewing it at over 700x, observers have mentioned that the elliptical inner disk is surrounded by fainter extensions that are reminiscent of Saturn's rings, hence the nickname. (Although NGC 6886 in Sagitta is also sometimes given the same nickname.)

 

In his post of 16 August 2018, Iain Petrie (CN'er iainp) from St Neots, Cambridgeshire, UK, remarked that IC 5217 "seemed very small to me, and it took 900 magnification to see its elongation and the difference between the brighter core and the fainter shell." Photographs reveal a bright equatorial ring and fainter bipolar lobes that extend north and south. Take a look at his very impressive sketch below!

 

Above: Magnificent sketch of IC 5217 as seen through Iain Petrie's (CN'er iainp) 20-inch (51-cm) reflector at 900x.

 

Finally, for those interested in the astrophysical aspects of this month's challenge, I would recommend reading IC 5217 as a Double-Shell, Point-Symmetric Planetary Nebula with a Very Narrow Waist by L. F. Miranda, S. Ayala, R. Vázquez, and P. F. Guillén [Astronomy and Astrophysics, 456, 591597 (2006)].

 

Have a favorite challenge object of your own?  I'd love to hear about it, as well as how you did with this month's test.  Contact me through my website or post to this month's discussion forum.

 

Until next month, remember that half of the fun is the thrill of the chase.  Game on!



About the Author:

Phil Harrington writes the monthly Binocular Universe column in Astronomy magazine and is the author of 9 books on astronomy.  Visit his web site at www.philharrington.net to learn more.

Phil Harrington's Cosmic Challenge is copyright 2022 by Philip S. Harrington.  All rights reserved.  No reproduction, in whole or in part, beyond single copies for use by an individual, is permitted without written permission of the copyright holder.

 


  • okiestarman56, John O'Hara, Starman2021 and 1 other like this


3 Comments

Small, but memorable. A nice challenge as I recall. Unfortunately, I could not make out any resemblance to its name sake. For those who haven't seen it, go see it. 

 

https://www.cloudyni...7#entry11471112

These little planetary's can be frustrating and a filter slide can really help. Unfortunately, the scope I was using last night, my 12.5 inch, is not equipped with one.

 

Last night I found myself back out n the high desert after my neighbor had his car totalled when he was rear ended. The moon set about 11 pm and IC 5217 was well positioned according to SkySafari. Phil is definitely right, finding it was a big part of the challenge. 

 

I used my star hopping tricks including first identifying the magnitude 6 cluster NGC 7243 to be sure I was in the right region. It happened to line up nicely with IC5217 for star hopping.  Splitting 4 Lac and Alpha Lac in my 50 mm RACI finder put me very close.

 

Attached Image: Screenshot_20220903-064021.png

 

But actually identifying 5217 in the star field was the challenge. I knew I was close and I'd observered some unique chains in the area in the main scope at 93x so I went back to Sky Safari, found I was very close and working between SkySafari and the scope, I was able to identify a short path to an oval asterism with 5217 as a member. 

 

Attached Image: Screenshot_20220903-065428.png

 

(Rotated 180° to match the Newtonian view)

 

Increasing the magnification, I was able to distinguish IC5217 as a non stellar object. It tried blinking it manually, holding the filter up to eyepiece with little luck. The seeing was so-so but I was able to get occasional glimpses of detail at 600x and 850x. It appeared to be slightly elongated with possibly a glimpse of a central star.

 

I'll be returning under better seeing with a larger scope.  These small planetary's are probably my least favorite deep sky objects, they're hard to find and identify and there's not a lot to be seen.

 

But last night, IC 5217 was a perfect fit and definitely qualified as the highlight of the night.

 

Thank you Phil once again for a memorable object and a memorable evening.

 

Jon

 

 

    • Dave Mitsky, PhilH, Asbytec and 2 others like this

These small planetary's are probably my least favorite deep sky objects, they're hard to find and identify and there's not a lot to be seen.

 

But last night, IC 5217 was a perfect fit and definitely qualified as the highlight of the night.

 

Thank you Phil once again for a memorable object and a memorable evening.

 

Jon

Hi Jon, I enjoy trying to see these little planetary nebulae. They are difficult, to be sure, but also interesting objects in their own right. I suspect a more than a few are out of reach for my aperture, some I have attempted were just not visible. But not all of them. I was pleased with IC 5217 even though I never got a glimpse of its apparent similarity to NGC 7009. The ability to see the pinch or bifurcated appearance was exciting enough. Frosty Leo was another. It was not Hubble like visually, but you could see enough to tell it was the same object (obviously because it was).

 

I bookmarked Phil's challenge page. I dunno, I just love the challenge of seeing these enigmatic things. The hunt can be enjoyable not knowing what to expect. The anticipation is worth the star hop. Of course, I'd prefer to see something rather than nothing. IC 5217 didn't disappoint. I'm glad you got a look at it. I am not alone, and now we have the shared experience of having seen it. I'd wish that experience for others. 

    • Jon Isaacs and PhilH like this


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