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Discovered by William Herschel in 1786.

This magnificient planetary is another prominent northern object missed byCharles Messier and discovered byWilliam Herschel, on February 15, 1786.The Cat Eye Nebula was the first planetary which was spectroscopically investigated and displayed its typical (and peculiar) line spectrum, by the English amateur astronomerWilliam Huggins, published originally in thePhilosophical Transactions of the Royal Society (London) in 1864 - in the same volume whereJohn Herschel published hisGeneral Catalog (GC) of 5079 entries for deep sky objects.(Huggins 1864).

NGC 6543 is situated almost exactly in the direction of the North Ecliptic Pole. This means that the normal vector of Earth's orbital plane (and alsothe total angular momentum vector of our solar system) points to a direction very close to this nebula, and that those diagrams of planetary orbits in the yearbooks and magazines represent the view of them from this planetary.

Our image was obtained by theHubble Space Telescope(Project scientists: J.P. Harrington and K.J. Borkowski, University of Maryland).A higher-res version andcaption (html) as well asPress Release text(PR 95-01a) is available.An enhanced b/w version ofthis image was released at the same time (PR 95-01b).

While the nebula, with its 20 arc second diameter, is rather small, it hasan extended halo of matter the progenitor star has ejected during its red giant phase. This halo measures 386 arc seconds (5.8 arc min) according to observations of A.G. Millikan (Millikan 1974).The brightest knot in this halo was discovered by E.E. Barnard, on April 24, 1900, and found its way into the IC catalog, with its own IC number, IC 4677.

Bill Arnett'sCateye Nebula NGC 6543 page(former The Web Nebula page).

In theSAC 110 best NGC object list.Caldwell 6 in Patrick Moore's list.In theRASC's Finest N.G.C. Objects Objects list.

IC 4677 (knot in the halo of NGC 6543, discovered by Barnard)

References

• William Huggins, 1864. On the Spectra of some of the Nebulae. Philosophical Transactions of the Royal Society of London, Vol. 154 (1864), pp. 437-444 [ADS: 1864RSPT..154..437H].
• Allen G. Millikan, 1974. Extended halos on planetary nebulae. Astronomical Journal, Vol. 79, No. 11, p. 1259 + Pl. II-III (November 1974) [ADS: 1974AJ.....79.1259M]

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Hartmut Frommert
Christine Kronberg
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Last Modification: October 14, 2013

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