NGC 6543: A Multiple-Ejection Planetary Nebula

OTA: OS 700 RC f/8
Camera: FLI PL16803
Observatory: Telescope Live, (SPA-2)

EXPOSURES:                
H: 21 x 600        
S: 23 x 600        
O: 24 x 600        
Total exposure    11.3 hours

Image Width: 21.6 arc-minutes
Processed by Alex Woronow (2022) using PixInsight, SWT, Topaz

Guiding Paradigms:
1.    Narrowband mapped to approximate True Color with H-beta inferred from Ha
2.    Show maximum detail in the nebula
3.    Reveal the presence of multiple episodes of ejections from the source star
Processing Challenges:
1.    The overlap among subframes occupied only the center 1/3 of the full-frame extent
2.    Tracking was poor in many subs, and stars were elongated up to half-again their PSF
3.    Star removal had to be done by hand because the bright central area was adversely affected by applications of both StarNet2 and StarXTerminator
4.    Ordinary procedures for star reinstatement could not be used because they resulted in bloated stars. (At the time of processing I had not discovered Bill Blanshan remarkable method; although the elongate stars would still be an issue.)

Telescope Live posted this data set as their Oct 2022 contest image. So, I gave it a try. (I did not win…an excellent, but indeed more conventional rendering, prevailed: https://telescope.live/gallery/cats-eye-nebula-5 )

This nebula has many sub-parts. The inner bubble (yellow and red in this image) comprises a complex of many bubbles, elongated in shape and filled with intensely hot gasses, resulting from the fast stellar wind emitted by the inner nebulae. Also, inside the dramatic flairs of the “cat’s eye” are many concentric rings that apparently formed before the source star left the Main Sequence. Those features attract the attention of professional astronomers (e.g., https://www.esa.int/Science_Exploration/Space_Science/Cat_s_Eye_Nebula_NGC_65432

But the bright blue circle of structures draws the focus of amateurs as those are the structures that their telescopes can access. Presumably, that bright halo represents an earlier eruption, although my internet search failed to substantiate this. My image also shows yet another faint, dispersed outer halo (blue) just below the main halo. This dispersed halo may be a still older ejection event—or just the other side of the main feature. But hints of several halos nested appear in this image, suggestive of multiple ejection events.

I hope you enjoy the image,
Alex Woronow