planetary nebula – Semper Iuvenis Photography

Imaging a Planetary Nebula in Cetus: The Skull Nebula

NGC 246, commonly known as the Skull Nebula (or Caldwell 56), is a planetary nebula. It is located about 1,600 light-years away in the constellation Cetus (The Whale). It gets its nickname from the appearance of the glowing gas shell surrounding its central stars. In certain orientations, this can resemble a human skull.

I chose to image this just by chance as I was perusing stellarium for targets. At -11 dec it’s a bit low for me, just over the tree line to the south. It was surprisingly bright at 180s subs. Very few stars in the area made guiding a challenge at 1625mm focal length.

Image acquisition and session automation by APT using a RC8 scope, ASI071MC Pro camera, and Eq6r Pro Mount. 176 subframes calibrated, integrated, and processed in PixInsight. Acquisition details and annotated image link.

The Bear Claw Planetary Nebula – Sh2-200

This is round two for me on this target. The first experienced significant reflections from the Antlia Quad Broadband LP filter. So, I’m back at it during the full moon using the Radian Ultra Quad-Band narrow band filter.
This beautiful but faint planetary nebula was imaged from my driveway at home. It was discovered in 1983 by the astronomers Herbert Hartl, Johann Dengel, and Ronald Weinberger. In 1987, further narrowband observations detected a large faint outer halo extending further than the central shell. However, it wasn’t confirmed to be a true genuine planetary nebula until 2017.

It has been given the name of Bear Claw Nebula for the imprint found on the central shell. Looks a lot like a bears print. This could be the faintest object I’ve ever attempted to image. After many hours of integration the Nebula began to appear. Individual subs showed absolutely nothing but stars and it is an impressive starfield! This is 15 hours of exposure using 156 6 minute subs.

Imaging sessions controlled and automated by Astro Photography Tool (APT 4.65.2). Two nights from 11/3/2025 using 360″ exposures on a RC8 telescope and ASI071MC camera atop an Eq6r Pro mount. 15 hours of exposure. Processed manually in Pixinsight.

Exploring Sh2-290: The Ancient Planetary Nebula

Sh2-290 (also known as Abell 31 or PK 219+31.1) is an ancient planetary nebula in the constellation of Cancer. It is estimated to be about 2,000 light years away.

Although it is one of the largest planetary nebulae in the sky, it is not very bright. The central star of the planetary nebula is a white dwarf with a spectral type of DAO. A planetary nebula is created when a low-mass star blows off its outer layers at the end of its life. The white dwarf is the dead remains of a star that existed but had died leaving behind Sh2-290. This is exactly what is expected of our star when it runs out of fuel in about 5 billion years.

Sh2-290 is made mostly of hydrogen and oxygen gas. The red gas signifies hydrogen gas, and the greenish hues signify the oxygen gas. The nebula has a bright central region being most of the nebula and a red ring around this blue/green region. The nebula, due to its ancient age, has its gas being dispersed into the interstellar medium.

This image was captured over five nights in January 2025. The image consists of 192 exposures, each lasting 5 minutes. These were taken with an f/8 RC8 telescope at 1626mm fl. An asi071MC color camera, cooled to 15f, was used atop a Skywatcher Eq6r pro mount. Image acquisition using Astro Photography Tool (APT) and processed manually in PixInsight.

Astrobin Link

Sh2-216 – Planetary Nebula

This is Sh2-216. It is a planetary nebula in the constellation Perseus. Planetary nebulae get their name because they are generally spherical. In the crude telescopes of centuries past, they appeared similar to the much closer planets of our own solar system. The astronomers of old did not realize the scale of our galaxy. They assumed these nebulae might be similar to our planetary brothers. This led to their name.

These objects are remnants of a stage in the death of larger stars. During this stage, stars convulse and blow off their outer layers of material into space. In the case of Sh2-216, the stellar explosion occurred some half million years ago. It left behind the core of the progenitor star, a white dwarf. There is also a slowly expanding cloud of mostly ionized hydrogen.

This particular object is the closest planetary nebula to us at only 400 light years distance. It’s proximity also makes it the largest in apparent diameter at 1.6 degrees – over three times that of our Moon. But it is very FAINT! The expanding hydrogen gas is extremely thin, requiring long exposure photography to show it. It is completely invisible to the naked eye, and isn’t visible in a single five minute camera exposure. This is a stack of 222 5 minute exposures, or 18.5 hours.

It won’t fit in my 860 mm Fl Esprit 120ED due to its size. Therefore, I focused on a bright outer band of gas. Image acquisition using APT 4.60. Processed manually in PI.

Astrobin – https://astrob.in/qwvo2i/0