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Observation by Mike Harlow: Planetary nebula NGC6543

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Mike Harlow


Mike Harlow


2022 Jan 14 - 05:30


2022 Jan 14 - 15:52


The Cat's Eye Nebula (NGC6543)

Planetarium overlay



Field centre

RA: 17h58m
Dec: +66°34'
Position angle: +2°12'

Field size

0°19' × 0°19'

  • 12 inch F/6.8 Astrograph
  • Starlight Xpress H16 CCD (2048 x 2048 pxl)
  • Astrodon luminance filter, 400 to 700 nm.
  • 26cm diameter, 3 degree objective prism

16 x 10 seconds for image, 24 x 30 seconds for spectrum


Ipswich, UK

Target name



Planetary nebula NGC6543

About this image

Some more recreational astronomy. After some success getting a spectrum of NGC2022 I thought I would try another planetary nebula.  NGC6543 is even smaller than NGC2022 but significantly brighter at ~mag 8.8.

In the composite image above A shows the rather sparse, 20 x 12 arc minute field containing NGC6543 and a small galaxy but little else.  The nebula is very over-exposed but image B at twice the original image scale shows some detail in the 22 x 18 arc second disc. (The central star is near mag 10.5).

The spectrum of the nebula, shown in D, is compared with that of an 'ordinary' star in C and nova Cas 2021 in E to help identify the elements giving rise to the monochromatic images of the planetary. 

Images due to the hydrogen Balmer lines are clearly visible although H beta is overwhelmed by the very bright O III emission image.  An image that could be due to He I emission corresponds to the position seen in the nova Cas spectrum.

A spectrum of NGC6543 taken in 1864 gave the first clear proof that at least some nebulae are made of gas rather than just being an unresolved cluster of stars.

Note: OK, the image isn't up to Peter Goodhew's standard(!!!), but the spectrum does add an extra dimension to the observation... And I was pleased to see that the faint smudge of light in A above (just above the '543') does correspond to the denser part of the extended envelope of the planetary.

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