The Helix Nebula (NGC 7293) is a planetary nebula (nothing really to do with planets though) some 650 light-years away, in the constellation Aquarius. It's composed of the remnants of a dying star that was once quite like our Sun.
Captured between 2021-08-27 and 2021-09-13.
Total Integration time: 7.81 hours
This is the first deep-sky object I've imaged in around 11 years. Technology has sure changed. I'm getting used to some new software and new equipment (well, new to me anyway). Plenty of mistakes were made, and plenty of lessons learned.
The Helix Nebula presents several challenges for me. I live in very light polluted skies (Bortle Class 8), and the Helix Nebula is not particularly bright, even though it is considered a "bright," planetary nebula.
From my vantage point, when not blocked by obstacles, it is fairly low to the horizon in the South-Southwest [in the direction of Mordor]. That's right where there's a ton of glare from neighborhood lights and also the same direction as the city skyglow [and let's not forget about evil forces and fiery Mt. Doom in Mordor]. Even with a telescope and an appropriate eyepiece, I probably couldn't even see it visually without of a long exposure camera [unless of course I slipped on the precious and entered the wraith-world, but that brings about its own issues].
In addition to the light-pollution, I also faced a broken-record's worth of coastal eddies that boosted the marine layer (resulting in clouds and haze); smoke from regional fires (I'm not even making that one up); [a gang of orcs]; guiding problems; the frustration of switching mid-project from a cheap guide-scope to an off-axis guider (OAG); [a nazgûl, but fortunately just the one (1 out of 9 max)]; tracking errors (oh, god the tracking errors -- my scope's gears could use a tune-up); A freak downpour that's practically unheard of in San Diego, California [or Hobbiton, The Shire], and some software compatibility weirdness.
------- Acquisition and processing details -------------
Equipment:
Meade 10" LX200-ACF (telescope)
Optec Lepus 0.62 Telecompressor
Astronomik RGB filters
Astronomik narrowband filters (SII, Hα, Oiii)
ZWO ASI1600MM (camera)
(various guiding equipment, not mentioned here.)
Software:
Nightime Imaging 'N' Astronomy (N.I.N.A.)
PixInsight
Topaz Denoise AI
Gnu Imaging Manipulation Program (GIMP)
Something of note is the flat frames were taken using a couple of white T-shirts (undershirts), a 14" embroidery ring, and a cheap, portable artists' "light box" used for sketching/tracing. The neat thing about that is the most expensive part was the bag of T-shirts.
The breakdown of filter integration is as follows (this only includes the "good" subframes, which were only about 50% of the total):
SII: 2.64 hours
Hα: 1.82 hours
Oiii: 1.58 hours
R: 0.56 hours
G: 0.56 hours
B: 0.65 hours
If you're wondering why there's so much more SII instead of Hα or Oiii, it's because the SII night was the about the only night the weather was cooperating.
Most of the processing was done in PixInsight. I'm brand new to PixInsight, so I'll spare you the details, since my workflow was all over the place. Suffice it to say, after calibrating, integrating, stretching and some color corrections, the color channels were combined using the PixelMath process in the following way:
Red Channel: 0.2R + 0.8Hα
Green Channel: 0.2G + 0.8Oiii
Blue Channel: 0.2B + 0.8SII
I think it came out okay, all things considered. But I look forward to improvements when I revisit the Helix Nebula in the coming years. [And I think all-in-all, the Dark Lord Sauron would be pleased.]
