The Saturn Nebula

Planetary Nebula NGC 7009

Caldwell 55

Apparent magnitude	8.0
Apparent dimensions	41″ × 35″
Constellation	Aquarius

Image exposure: 51 Minutes

Image field of view: 5 x 5 arcmin (estimated)

Image date: 2021-10-31

This is a beautiful and unique planetary nebula, estimated to be roughly 3000 light years away. It consists of an intricate web of gas emissions* from the 11th magnitude central star, as it transformed from a low mass main sequence star into the hot (55,000 K) white dwarf it is today.

*This paper by Walsh et al (table 3) indicates that hydrogen helium, nitrogen, oxygen, sulfur and chlorine are the abundant elements in NGC 7009 (not that I have any expertise in reading scientific papers).

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This object has nothing to do with Saturn or any other planet.

It is called a planetary nebula because back in the early days of telescope astronomy it was noticed that such objects were not point-like stars but had a discernible diameter, just like planets do. They didn’t know what they were but unfortunately the name has stuck – as have the names of many of the objects discovered in the infancy of modern astronomy.

It was called the Saturn Nebula because in over-exposed images, like the one below, it has a Saturn-like appearance which is not detected in images intended to record the structure of the main nebula. When I look at the above image from the side of the screen, I can see the ghostly shape of faint green nebulosity surrounding it which hints at its name. I don’t know if all screens will do this.

Over-exposed image of NGC 7009
from the Simbad Data Base

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This was the first test night for my new configuration and my first night back on the front driveway after the ending of our three months covid confinement. I expected some hiccups but they turned out to be very minor and user-centric. 🥴

My Meade LX-90 telescope on EQ6R-Pro mount.

More planetary nebulae to come…..

Cosmic Focus Observatory

34° S

Above us only sky….

Telescope:	Meade LX-90 2000mm focal length, 203 mm dia
Optics:	Astronomik light pollution filter.
Mount & Guiding:	SkyWatcher EQ6-R Pro mount.
Imaging camera:	ZWO ASI 071 MC cooled.

^{Images © Roger Powell}
🙃
^{I’m one of the founder members of Macarthur Astronomical Society}

Do it!