NGC 6543, the Cat's Eye Nebula, Narrowband

This is a Narrowband version of the previous image. The details follow:

NGC 6543, the Cat's Eye Nebula, is a planetary nebula located in the constellation Draco. Planetary nebulas are remnants of a star at the end of it's life. A star similar to our Sun. It blows off it's outer shells forming the nebula. The core of the star collapses to form a dense hot white dwarf. The radiation from the white dwarf excites the gas in the nebula causing it to glow. (NASA Science)

The Cat's Eye Nebula was a favorite object for me to observe when I was a staff telescope operator at Lick Observatory. I frequently observed it through the 36 Inch Great Refractor and the Nickel's 1-M Reflector. I did so during public events at the observatory.

What is interesting is that viewing the Cat's Eye through these telescopes you only see the inner bright core, about 1/3.. The dimmer halo with tendrils that composes most of the nebula is not visible.

This image is a narrowband image, (HOOS). It enhances the planetary nebulas contribution of H-alpha, OIII, and SII.

The table below shows the RGB channel assignments as well as the addition of a yellow channel. Assignments are as follows:

Channel --> Narrowband

Red --> H-alpha

Green --> OIII

Blue --> OIII

Yellow --> SII

Stars are standard RGB color.

The purpose of this Narrowband image is to show the composition of the planetary nebula. The ejection of the stars atmosphere pushes the gas outward. Hydrogen compared to oxygen and sulfur is very light. Therefore, oxygen (greenish blue or teel) and sulfur (yellow) compose the inner part of the nebula. Hydrogen (red) is located beyond the core of the planetary nebula.

Image processed by Andrew Macica, original data from Telescope Live.

Imaging Details:

Observatory: Oria, Spain

Telescope: Officina Stellare 700 RC

Aperture: 700 mm (27.5 inches), f/8

Focal Length: 5600 mm

Camera: QHY 600M Pro CMOS

Filters: H-alpha, OIII, OIII, SII

Total Exposure: 8 hours 35 min.

Image Processing:

PixInsight 1.8.9-3 Ripley (x64);

BlurXTerminator, NoiseXTerminator, StarXTerminator (RC Astro);

Adobe Photoshop 25.12.4;

Adobe Lightroom Classic 15.0.1

Instruction on PixInsight from Adam Block Studios.