NGC 6543, mag. +8.2, also known as the Cat's Eye Nebula is a bright planetary nebula located in the northern constellation of Draco. It was discovered by William Herschel on February 15, 1786 and is one of the brightest and finest examples of its type. Some of the most spectacularly images ever taken by the Hubble Space Telescope have been of NGC 6543. They display a wealth of exquisite details across a large complex eye-like structure.

In total, the extended halo of the nebula spans some 6.5 arc minutes of apparent sky. However, through amateur scopes only the small inner section is visible (approx. 20 arc seconds) and therefore it appears tiny and considerably smaller in apparent size than for example, Jupiter. However, the advantage of a compact centre is a high surface brightness and NGC 6543 can be spotted with binoculars and is easily visible through small scopes.

NGC 6543 The Cat's Eye Nebula by the Hubble Space Telescope (NASA, The Hubble Heritage Team (AURA/STScI))

Finder Chart for NGC 6543 (credit:- freestarcharts)

Finder Chart for NGC 6543 - pdf format (credit:- freestarcharts)

The Cat's Eye is located in a barren region of sky near the centre of sprawling Draco. It's positioned 13 degrees north of Eltanin (γ Dra), which at mag. +2.2 is the brightest star in the constellation. The nebula lies between delta (δ - mag. +3.1) and zeta Dra (ζ - mag. +3.2) and at about the centre point of an imaginary line connecting 5th magnitude stars, 27 Dra and 42 Dra. Interestingly, NGC 6543 sits nearly exactly on top of the ecliptic north pole. It's best seen from the Northern Hemisphere during the months of June, July and August and is circumpolar from latitudes above 24N.

In most scopes, NGC 6543 appears as a tiny, bluish green spot of bright nebulosity. An 80mm (3.1-inch) refractor reveals an evenly lit slightly oval small disk that responds well to high power. On initial inspection it may appear stellar but higher magnifications easily reveal its true nature. A 200mm (8-inch) scope hints at some colour but generally larger instruments of at least 300mm (12-inch) are needed to tease out finer details. Although the central star shines at mag. +11.4, it takes a large instrument at high powers to spot it due to the overwhelming brightness of the surrounding nebula. Of course, even on the best nights, NGC 6543 won't look anywhere near as spectacular as seen in the Hubble images.

NGC 6543 is 3,300 light-years distant and is estimated to be about 1,000 years old. It has a temperature between 7000 and 9000 K, which is hotter than the surface of the Sun. In the Caldwell catalogue, the object is listed as number 6.

NGC 6543 Data Table

NameCat's Eye Nebula
Object TypePlanetary Nebula
Distance (kly)3.3
Apparent Mag.8.2
RA (J2000)17h 58m 33s
DEC (J2000)66d 38m 00s
Apparent Size (arcsecs)20 x 16 (centre)
Radius (light-years)0.15 (centre)
Other NamesSnail Nebula, Sunflower Nebula
FeaturesCentral star mag. +11.4, positioned close to Ecliptic North Pole

Sky Highlights - September 2017

Neptune reaches opposition on September 5th

The Planets
This Month's Guide

Algol Minima
Algol eclipse dates and times for September

Northern Hemisphere
West:- Jupiter (mag. -1.7)
Southwest:- Saturn (mag. +0.5)
East:- Neptune (mag. +7.8)
South:- Neptune
East:- Uranus (mag. +5.7)
West:- Neptune
South:- Uranus
East:- Venus (mag. -3.9), Mars (mag. +1.8) (from second week), Mercury (mag. +0.5 to -1.3) (from second week)

Southern Hemisphere
West:- Jupiter
Northwest:- Saturn
East:- Neptune
West:- Saturn
North:- Neptune
Northeast:- Uranus
West:- Neptune
Northwest:- Uranus
Northeast:- Venus
East:- Mars (end of month)

Deep Sky

Small telescopes:-
Messier 13 - M13 - Great Hercules Globular Cluster
Messier 92 - M92 - Globular Cluster
Messier 11 - M11 - The Wild Duck Cluster (Open Cluster)
Messier 7 - M7 - The Ptolemy Cluster (Open Cluster)
Messier 6 - M6 - The Butterfly Cluster (Open Cluster)
Messier 4 - M4 - Globular Cluster
Messier 8 - M8 - Lagoon Nebula (Emission Nebula)
Messier 16 - M16 - Eagle Nebula (Emission Nebula with Open Cluster)
Messier 20 - M20 - Trifid Nebula (Emission and Reflection Nebula)

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