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Cat's Eye Nebula

NGC 6543, HD 164963, PK 096+29 1, Sunflower Nebula, Snail Nebula, Caldwell 6, Cat's Eye Nebula, IV 37, GC 4373

RA: 17h 58m 33.423s
Dec: +66° 37′ 59.52″

Con: Draco
Ch: MSA:1066, U2:30, SA:3

Ref: SIMBAD

(reference key)

Type: planetary nebula

Mag: B=9.8, V=?

Size: ?
PA: ?

Image gallery

Photos  (1)

Select a photo and click the button to view

History and Accurate Positions for the NGC/IC Objects (Corwin 2004)

NGC 6543 is the famous planetary near the north ecliptic pole. See IC 4677 for a bit more about it.

Remarks

A planetary nebula in Draco, at magnitude 8.8, one of the brighter planetaries.

Historical observations

William Herschel (c.1784)

Synonyms: H IV-037

Discovered in 1786 by William Herschel with an 18.7-inch f/13 speculum telescope. He called it "a planetary nebula, vB, has a disk of about 35 arcseconds diameter, but very ill defined edge. With long attention a vB well defined round centre becomes visible." In the Philosophical Transactions, 1791, Herschel wrote: "On the 15th of February, 1786, I discovered that one of my planetary nebulae has a spot in the center, which was more luminous than the rest, and with long attention, a very bright, round, well defined center became visible. I remained not a single moment in doubt, but that the bright centre was connected with the rest of the apparent disk."

Webb, T.W. (1893)

In the 5th edition of Webb's Celestial Objects for Common Telescopes it is described as "Planetary, very curious. D'Arrest 'unica prope inter nebulas.' I found very luminous disc, much like a considerable star out of focues. Herschel, 35 arcsecond diameter, I saw but 15 or 20 arcseconds with 3.7-inch: d;Arrest 23x18 arcseconds. Smyth, pale blue. Herschel, very small nucleus; Bird 1863 12-inch silver mirror, like a 10th mag star; d'Arrrest 11-12th mag, with Huggins, gaseous spectrum; the first of these surprising discoveries, 1864, August 29. Nearly halfway between Polaris and Gamma Draconis in pole of Ecliptic. About 40' N.p. Bird finds a delicate triple star, 8.9, 9, 11.8."

Burnham, S.W. (1894)

Burnham, S. W. () "Measures of planetary nebulae with the 36-inch equatorial of the Lick Observatory", Pub. Lick Obs., vol 2, p159-167. "This is the well known planetarynebula in Draco. It has been more frequenhtly observed thanany other object of this class, with the exception of the ring nebula in Lyra."

Holmes, Edwin (1896)

"The Nebula H 37 IV."

[1896JBAA....6..438H]

Published comments

Doig, P. (1925)

Doig, P. (1925) Notes on the nebulae and clusters in Webb's 'Celestial Objects for Common Telescopes' (Sixth edition, Vol.ii). Part I. M.N.R.A.S., 35(5), 159.

Terzian, Y. (1980)

Terzian Y (1980) Q.J. R.astr.Soc vol 21, p82-92 [09.16.1] notes that the central star of this planetary is a spectroscopic binary, and the nebula has a faint outer giant halo.

Sulentic & Tifft (1973)

The RNGC (Sulentic and Tifft 1973) notes that this is a 9.0 mag planetary nebula.

Photo index

Photo Index by Jim Lucyk: Sky&Tel. 6/79 p601, Sky&Tel. 7/69 p13 (drawing), Sky&Tel. 7/85 p89, Sky&Tel. 11/69 p309, Astronomy mag. 9/74 p26, Deep Sky #6 Sp84 p13, Burnhams V2 p1174, Sky&Tel. 10/87 p440.

[amastro] Distance "guess" for NGC 6543

On the Los Alamos preprint server is a paper based on HST data that uses an expansion measurement of the planetary NGC 6543 to estimate the distance to be 1001 +/- 269 parsecs. Even neglecting the insignificant figures ("1.0 kpc +/- 0.3" would have been more realistic), I guess we can now tell people that this object is about 3000 light-years away.

This paper (you can read it at: http://xxx.lanl.gov/abs/astro-ph/9907313) will be published in the AJ.

Brian

Burnham's Celestial Handbook

Burnham notes that the nebula exhibits similar structure to the Helix Nebula, NGC 7293.

Modern observations

Walter Scott Houston

Houston notes that this object has a "distinctive colour. . . . Visible in telescopes with apertures as small as 3 inches, its 15 arcsecond diameter disk shines with the total light of an 8.8 magnitude star, making its surface brightness rather high. ... Several years ago I received a letter from Michael Gardner ... [who said he once] observed at the broken-Cassegrain focus of the 60-inch [at Mount Wilson Observatory] where a 55mm eyepiece yielded 450x and a field only 6' wide. His reaction to viewing NGC 6543 was 'Oh, the colours .. a stunning blue-green oval with colours like a Kodachrome.' "

Houston notes that this 9th mag glow is well seen in his 4-inch refractor.

Archinal, Brent (IAAC)

Subject: > (IAAC) Obj: NGC 6543 - Inst: 30" f4 dob

"Of interest was a dim, diffuse, hazy patch of nebulousity about 60 seconds west of ngc 6543. The nebulousity was about twice the diameter of the planetary. It was near the apex of a triangle of dim stars and about two thirds of the way to the nearest bright field star to the west of ngc 6543. This object is not plotted in Sky Atlas 2000. Can anyone tell me what this object is? I have observed ngc 6543 many times over the years and never noticed any other nebulousity in the field."

Mark and others -

I don't know if anyone else has replied on this yet (I'm only receiving the digest version of the netastrocatalog messages), but this object is pretty definitely IC 4677. This was discovered by E. E. Barnard with the Yerkes 40-inch refractor on April 24, 1900. IC 4677 has in the past been incorrectly considered a galaxy. This is noted in the NED database. Leos Ondra (ondra@physics.muni.cz) was recently (this past June) able to locate Barnard's original observations, confirming the identification of this. The original observations are available at the Yerkes Observatory Library, Barnard's observing book #24, pages 140-144. Steve Gottlieb (sgottlieb@telis.org) has also recently observed this object. The supposition is that this is actually part of an outer shell of NGC 6543.

- Brent

Sanford (1989) Observing the Constellations

Sanford calls it "one of the best ... appears as a vivid blue disk, of about 8th magnitude and 18 arcseconds in diameter. There is a fairly complex, but difficult to discern, internal structure, and a central star which can be seen with averted vision but not as easily directly."

(unknown)

(PK96+29.1) Mag=8.1. The Cat's Eye Nebula in Draco: 17h, 58.6m; +66 38' Ferguson discerned surface irregularity with his tiny Questar scope; in our 8" aperture richfield instrument, this medium-sized (20"+ diameter) planetary was a bright, fairly even oval disk, with almost no variance in luminosity until scrutinized with a 2.5 mm ocular providing over 400x. Thus, differences in telescope, exit pupil, sky condition, and observer cause a divergence of opinions! The high surface brightness requires only a moderately-dark sky for a good view: an oxygen filter seemed merely to help darken the background. An excellent object that unfortunately yields little of its wild shapes and gorgeous colors, depicted in the fabulous Hubble image on the cover of the April 1995 Sky&TelESCOPE magazine: a similar Hubble image by Dr. Bruce Balick is found on his "Fast Low-Ionization Emission Region" homepage, a Wide-Field Planetary Camera image in a 55k gif file .

Mullaney, J

Mullaney calls this a "bright planetary .. its luminous blue disk looks like a star out of focus and is an easy target in 3- and 4-inch telescopes at medium powers. A 9th magnitude object measuring 22 arcseconds in diameter, it is sometimes called the Sunflower or Snail nebula. Here's another islolated and neglected object well worth searching out."

Bortle, John (1976)

John Bortle (Webb Society Quarterly Journal, January 1976) using 10x50 binoculars, estimates the visual magnitude as 8.3.

Kaler, James B

James B. Kaler ("The Amateur Scientist", Scientific American, May 1992) notes: " . . an extraordinary nebula, both visually and historically. In 1864 William Huggins observed the spectrum and discovered that it has mysterious features known as the nebulium lines. They were identified some 64 years later by Ira S Bowen of Caltech as doubly ionixed oxygen. Through a telesocpe, NGC 6543 looks ghostly green. 'No mistaking this one' said Clive Cadle, peering through his 10-inch. He could glimpse the central star [using averted vision]. When Barbara Wilson observed it using a 20-inch scope, she thought the nebula looked 'like a cat's eye, a green oval with a dark ovoid.' She was easily able to see the central star."

Tom Lorenzin

Tom Lorenzin, in the e-version of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing", notes: "8.6M; 22" x 16" extent; bright and small, bluish ellipse with 10M center star use high-x and N-filter; 11.5M star 4' to NNW."

Martin, N.J. (IAAC)

Observer:N.J.Martin Your skill:intermediate Date and UT of observation:09/10 September 1997 01.00 Location & latitude:near Ayr South West Scotland lat 55 24'56" Site classification:bright rural Limiting magnitude (visual):6 (zenith) 4 at altitude 11 degree of nebula Seeing (1 to 5 - best to worst):2 Moon up (phase?):no Instrument:20" f4.4 Dobsonian >Magnification:X86, X248 >Filters used:None, Lumicon UHC >Object:NGC 6543 Cats eye nebula >Category:Planetary nebula >Constellation:Draco >Object data:mag 7.6 22"X16" >RA/DE: RA 17 58' Dec 66 38'

]Description: This was my first view of the splendid Cat's eye nebula and I can recommend it as a must for all observers. At low magnification the nebula is a bright blue green (duck egg blue). There is a definite red edge to it. The cats eye is difficult to see at X86 but appears at higher magnification. It is very clear at X130( roughly) with the central star surrounded by a darker area in a complex structured sharp edged elliptical nebulosity. The enlargement of the star's Airy disc by the seeing made the cat's eye appearance more striking. If the focus was not exact or the seeing particularily bad the star vanished into the nebulous background. At X248 The structure was best seen and there was always a suggestion of more structure at the limit of perception. The colour was much less striking and the nebula was obviously not elliptical. The brightest nebulosity was a rough rectangle in the direction NW-SE with a triangular extension in the easterly (preceding) direction. The westerly (following) extension was fainter and there was an indentation like a bite out of the north westerly edge. The centre was darker but with nebulosity still present and the eye appearance not as obvious as at lower magnifications. For novices to save you the trouble I had last night (poor searching technique). Finding it. There is a little line of three 5/6 magnitude stars just off the line between zeta and delta Draco. From the brightest (42 Draco) move towards zeta the length of the line in the direction of the last two stars of the line. There is a 7/8 magnitude star. Go in the same direction and distance again. In the finder there is another 8 magnitude object. This is the Cat's eye. It looks slightly fuzzier than a star but not obviously.

Maloney, Patrick (IAAC)

(IAAC) Obj: NGC 6543 / Cat's Eye Neb - Inst: 10" Starsplitter Newtonian

Observer: Patrick Maloney Your skills: Advanced (many years) Date/time of observation: 02/Aug/1998 0735UT Location of site: Palisades-Dows Observatory, Nr Cedar Rapids, Iowa (Lat , Elev ) Site classification: Rural Sky darkness: 6.0 Limiting magnitude Seeing: 7 1-10 Seeing Scale (10 best) Moon presence: None - moon not in sky Instrument: 10" Starsplitter Newtonian Magnification: x318 Filter(s): Object(s): NGC 6534 / Cat's Eye Neb Category: Planetary nebula. Class: IIIa Constellation: Dra Data: mag 8.1 size Position: RA : DEC :

Description: Very bright. A smooth oval which grows brighter towards the centre where there is a very bright central star or central condensation. At the south east extremity there appears to be a small, faint extension.

[amastro] pn N6543 (Cat's Eye) & galaxy

While viewing the fantastic N6543 (Cat's Eye) PN in a 25" f/5 I noticed a slight haze just to the west of the object. MegaStar shows it as 15.7 magnitude galaxy IC 4677 (17h 58m 14.5s +66 37' 54"). Has anyone observed it? It's odd. I see it easiest at 228x. It can't stand too much power. What's odd is this galaxy shows best with the above mentioned magnification and an OIII filter. I've seen the Deep Sky filter help on a few galaxies, but never an OIII. So, is it really a galaxy?

Does anyone have a more accurate visual magnitude, as it appears brighter than 15.7?

Kent Blackwell

Virginia Beach, VA

------------------------------------------------------------------------

Re: the object west of the Cat's eye. NGC 6543 has a rather patchy outer shell which is visible at moderate to high powers. The brightest patch is slightly to the west of the nebula, and is often mistaken for a galaxy. It is small and elongated, but I am uncertain whether Megastar is incorrect on this one (might be). I have seen this patch (as well as other parts of the shell) in my ten inch under excellent conditions. Clear skies to you.

--

David Knisely KA0CZC@alltel.net

Prairie Astronomy Club, Inc. http://www.4w.com/pac

------------------------------------------------------------------------

Yes, part of the shell around NGC 6543, which was observed by Barnard first, I think, resulting in the IC number, is erroneously catalogued as a galaxy in the MCG (elsewhere?).

Brian

------------------------------------------------------------------------

Kent,

Its a bright knot in the outer halo of the galaxy. It has been seen by others on this listserv, with instruments of only moderate size.

- Rich

------------------------------------------------------------------------

I think the galaxy (if it is a galaxy) I saw is not the patchy neby you saw. It's a bit too far from the body of the Cat's Eye. Still you might be right. Has anyone else seen this galaxy (or patch)?

Kent Blackwell

------------------------------------------------------------------------

IC 4677 is really a knot in NGC 6543's halo, discovered by Barnard visually with the Yerkes 40-inch. The original record(s) survive at Yerkes. See the website of the NGC/IC project.

Best, Leos

Leos Ondra, Skretova 6, 621 00 Brno, Czech Republic

------------------------------------------------------------------------

Kent Blackwell posted:

] I think the galaxy (if it is a galaxy) I saw is not the patchy neby you

] saw. It's a bit too far from the body of the Cat's Eye. Still you

] might be right. Has anyone else seen this galaxy (or patch)?

]

I did a little measurement on the Digital Sky Survey (First Generation) image of NGC 6543. The "patch" of IC 4677 is located on the image about 1.8 arc minutes west of the center of NGC 6543, and matches the distance from the "center" of the plotted "galaxy" on Megastar (as well as fitting very well into the star pattern shown on Megastar and the DSS image), so it does indeed appear to be just a portion of the outer shell of that planetary. The outer shell of NGC 6543 is probably 2 arc minutes in radius, but that varies with position angle (the main portion of the nebula itself is around 22" x 16" if memory serves). The next brightest patch is to the east-southeast of the center of the planetary. The rest of the shell usually appears as a very faint glow with little structure. With a 30 inch Obsession at this year's Nebraska Star Party, the western patch and hints of a few others were visible without much difficulty, although most of us were more interested in the spiral-like detail in the inner shell (using a binoviewer, the view was outstanding). There is supposed to be a galaxy about 9.4 arc minutes to the east of NGC 6543 (NGC 6552?), but I don't recall seeing it. Clear skies to you.

David Knisely KA0CZC@alltel.net

Prairie Astronomy Club, Inc. http://www.4w.com/pac

Albino, Adam (IAAC)

Your skills: Intermediate (some years) Sky darkness: 5.2 Limiting magnitude Seeing: 7 1-10 Seeing Scale (10 best) Moon presence: None - moon not in sky Instrument: Ultima C-8 PEC w/ 80mm f/10 MAK

Bright, round/elongated, large. Typical "neon" glow which makes planetaries stand out for me. Does anyone see blue green???? Core darker (ring apperence) except at 254x some knotting in center was seen.

See also notes to IC 4677.

Brian Skiff

7x35mm - brtr of two *s aligned E-W. BS, 28Jun1992, Hutch Mtn.

6cm - vis as * next to another * W.

15cm - about as br as N6210 but much bigger. seems velong, sort of pointed at the ends. 30"x20". no real detail and no cen *. bluish. HM, 3Mar1971, FtL.

- vbr & obvious @ 50x SE of m9 *. 80x: using direct vision (vdifficult!) the central * seems plain despite br surroundings. 155x/325x: core is lentic in pa30; vmuch fntr circ halo surrounds this. no cen * w/direct or averted vis. SW end of core seems disturbed. dm w/* NW is ~1.5 using 50x out-of-focus. BS, 2Jul1992, Anderson Mesa.

25cm - recog @ 47x. 240x shows it elong NE-SW, 50"x30". featureless & grey, no cen *. at lox it's like a m9 *. BS.

- pa15. not quite symmetrically oval: N end rounded, S side more diffuse, more sharply tapered. N portion also seems to have br spot, not *-like, but a concen of light. well-def border w.f halo around it 20" wide. 245x.

30cm - vbr & oval, elong N-S. 220x: 20"x15" in pa20. vsmooth white texture. Nrn 2/3 is brtr w/a few vsm br spots on periphery. smooth @ 440x, but Srn diffuse end seems to be a hole in pn. Nrn part has a broken br edge on E&W, but edge mostly sharp.

Contemporary observations

Tom Bryant

2007-09-12 22:00:00

Observing site: Pinnacles overlook

Telescope: C-8

[17h 58m 36s, 66 38m 0s] A bright, pale blue disc. Not at all like it's HST photos!

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