Hemisphere:  Northern  ·  Constellation: Draco (Dra)  ·  Contains:  IC 4677  ·  NGC 6543
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The Cats Eye Nebula, NGC 6543, Caldwell 6, 


            Steven Bellavia
The Cats Eye Nebula, NGC 6543, Caldwell 6
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The Cats Eye Nebula, NGC 6543, Caldwell 6

Technical card

Imaging telescopes or lenses: Celestron C5 Schmidt-Cassegrain  ·  Borg 90FL

Imaging cameras: ZWO ASI533MC Pro  ·  ZWO ASI 183MM Pro

Mounts: Celestron AVX Mount

Guiding telescopes or lenses: Agena Astro 50mm f/3.9 Guidescope

Guiding cameras: ASI224MC

Software: IDEIKI AstroPhotography Tool (APT)  ·  Stark Labs Nebulosity 4.2  ·  Digital Photo Professional  ·  Plieades Astrophoto PinInsight 1.8  ·  Annie's Astro Actions V7  ·  Noel Carboni's Astro Tools for PhotoShop Noel Carboni Actions  ·  SharpCap Pro 3.2  ·  PHD2 Guiding

Filters: Astronomik 6nm OIII  ·  ZWO Duo-Band Filter  ·  Optolong 7nm Ha 2"

Accessory: Celestron OAG #93648  ·  Borg 1.08X DG Multi-Flattener, #7108

Dates:Aug. 4, 2018Aug. 5, 2018June 12, 2020

Astronomik 6nm OIII: 24x300" (gain: 100.00) -15C bin 1x1
Optolong 7nm Ha 2": 24x300" (gain: 100.00) -15C bin 1x1
ZWO Duo-Band Filter: 60x180" (gain: 100.00) -5C bin 1x1

Integration: 7.0 hours

Darks: ~37

Flats: ~30

Flat darks: ~30

Avg. Moon age: 22.08 days

Avg. Moon phase: 50.77%

Bortle Dark-Sky Scale: 4.00

Mean SQM: 20.80

Mean FWHM: 4.00

Temperature: 18.00

Basic astrometry details

Astrometry.net job: 2187435

RA center: 17h 58' 33"

DEC center: +66° 38' 2"

Pixel scale: 0.898 arcsec/pixel

Orientation: 178.121 degrees

Field radius: 0.450 degrees

Resolution: 3000x2000

Data source: Backyard


The Cat's Eye Nebula, Caldwell 6, NGC 6543, is a relatively bright planetary nebula in the constellation of Draco, discovered by William Herschel on February 15, 1786. Herschel compared the nebula’s appearance to that of the disk of an outer planet when seen through a small telescope, which is how planetary nebulae got their name.

It is 3,300 light years from Earth.  It was formed around 1,000 years ago when a hot, bright central star expelled its outer envelope.  The nebula appears as a diffuse blue-green disk when viewed with small telescopes.

The central progenitor star is an O7 Wolf-Rayet-type star, about 10,000 times brighter than our Sun, but 35% smaller in diameter. The star has a temperature of about 80,000 K (compared to our sun's 6,000 K). It is losing around 20 trillion tons of mass per second in a fast stellar wind. The star is believed to have originally had a mass of around 5 times our sun. The stellar wind has a velocity of around 1,900 km/s.

The Cat’s Eye Nebula is expanding at a speed of 16.4 km/s. Its angular expansion rate is 3.457 mili-arc-seconds per year.
The nebula’s core has an apparent size of 20” and a high surface brightness.

Note that the brighter portion of the outer halo of the cat's eye is considered IC 4677.
Also, distant galaxy NGC 6552 (370 million light years) is also in the image, to the right (East) of the cat's eye.



  • The Cats Eye Nebula, NGC 6543, Caldwell 6, 


            Steven Bellavia
  • Final
    The Cats Eye Nebula, NGC 6543, Caldwell 6, 


            Steven Bellavia

Sky plot

Sky plot


The Cats Eye Nebula, NGC 6543, Caldwell 6, 


            Steven Bellavia