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The Medusa (Abell 21) Interrupted: 23 hours of S(no H)O, Rick Veregin
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The Medusa (Abell 21) Interrupted: 23 hours of S(no H)O

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The Medusa (Abell 21) Interrupted: 23 hours of S(no H)O, Rick Veregin
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The Medusa (Abell 21) Interrupted: 23 hours of S(no H)O

Equipment

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Acquisition details

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Description

Why SO with no H?
  • This was one of my late winter projects, to capture the Medusa in SHO. Since I’m using a OSC camera, I started with my SO filter, with the intention of switching over to HO to finish.
  • However, the winter skies were even more horrible than usual, so not only did I not get HO yet, but also the SO was still short of where I needed to be. I’m in Bortle 8, so even with narrow band filters I need plenty of integration time. And to top it off, SII and OIII are very weak in the Medusa anyway, it is mostly emitting in Halpha.

Why post it?
  • I have not seen an SO image on AB, or anywhere, for that matter, so it does put this amazing target into a new light, so to speak. I hope others out there are interested to see a new look. Hopefully next year I can finish the SHO image, so there can be a nice comparison, SO, HO, and SHO.🤞🤞

The Medusa Nebula
  • At 4 light years across and 1500 light years distance the Medusa due to its large size in the sky.
  • It is an old planetary nebula (about 8000 years old, near the end of the usual 10,000-year life span of PN.
  • PN are formed from low mass stars like our own Sun, that are not massive enough to go supernova as they near the end of their lives. Instead as these stars age through the asymptotic giant branch (AGB), that is the Red Giant stage, they expel gas, which starts the formation of the nebula.
  • These very hot stars continues to expel gas intermittently, creating the complex nebular structures. As these stars get hotter they emit more UV radiation, which ionizes the gas in the nebula.
  • For the Medusa Nebula that central star is a PG 1159 star. These stars are pre-degenerate with hydrogen-deficient atmospheres and surface temperatures of 75,000 Kelvin to 200,000 Kelvin. Eventually this star will lose its hydrogen and what will remain in the end is the electron-degenerate carbon-oxygen core of a white dwarf.

My Processing
  • DeepSkyStacker: SO data calibration, registration and stacking.
  • StarTools: Bin @ 71% (i.e. 1.41x1.41), background wipe, development, deconvolution, color, and isolation.
  • Photoshop: Star and nebula layer separation using StarXterminator (so yes, those are SO stars), nebulosity multi-scale unsharp mask with APF-R, noise reduction with NoiseXterminator, color adjustments (selective color, vibrance, red and blue saturation, levels background neutralization), and finally stars added on top of nebulosity with Linear dodge (add).

Comments

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The Medusa (Abell 21) Interrupted: 23 hours of S(no H)O, Rick Veregin

In these public groups

AstroBin Platform open discussions community forum
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SharpCap Users
ZWO ASI 2600MC PRO
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