Here is the Helix Nebula, NGC 7293. It has also been called the Eye of God, or the Eye of Sauron.
The Helix Nebula is a perfect example of a Planetary Nebula, formed by an intermediate to low-mass star, which sheds its outer layers near the end of its life. Gases from the star in the surrounding space appear, from our perspective, as if we are looking down a helix structure. The remnant central star of the planetary nebula is destined to become a white dwarf star, and can be seen in this image. The radiance from the central star is so energetic that it causes the previously expelled gases to brightly glow.
This is an interesting example of how the nebula’s structure can be revealed by knowing how the image was captured. The outer edges shown in red are glowing molecular hydrogen, which is captured through the hydrogen alpha filter. The greens and blues are generated by ionized oxygen, captured through the Oxygen III filter, and lastly the central blue area is energized gas glowing at the Sulphur II line, and are captured by the Sulphur II filter. This is known as an HOS image, where Hydrogen Alpha maps to Red, Oxygen III is mapped to Green, and Sulphur II is mapped to Blue.
This target is a tad small for the little astrophotography kit I am currently using; there is not enough focal length to provide a lot of detail. It will be examined much more closely when the new 12″ RItchey scope is in action.
Image Info
- Imaged from the KPO field in Saint Cloud, Florida.
- Camera : ZWO ASI1600MM Pro
- Lens: Canon 100-400 f/5.6L lens, set to 387mm
- Mount: iOptron SmartEQ Pro
- Hydrogen Alpha: 24 subframes of 300s = 120 min integration, assigned to Red
- Oxygen III: 22 subframes of 300s = 110 min integration, assigned to Green
- Sulphur II: 6 subframes of 600s = 60 min integration, assigned to Blue
- Total integration time: 290 min = 4.8 hours.
- Captured via ASIAir Pro automation
- Optical tracking via ASIAir automation, currently using ST4 mount control via the ASI120MM-S guide camera
- Separate channels stacked and HOS integrated in Astro Pixel Processor
- Final processing in Aperture
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