The Dumbbell Nebula (Messier 27, NGC 6853), is a planetary nebula located 1,400ly away in the constellation Vulpeca. In 1764, it was discovered by Charles Messier; the first of it's kind. However, the term planetary nebula (really a misnomer) was coined by William Herschel, because it reminded him of his newly discovered planet, Uranus.

As with all planetary nebulae, M 27's central white dwarf is the collapsed core of a formerly sunlike star which, after exhausting its hydrogen fuel, become a red giant and ejected its outer layers. The expanding gas shell is excited by high-energy radiation from the central white dwarf star, forming the visible nebula. The star is so much fainter than the nebula because it emits mainly in the non-visible part of the spectrum. This invisible ultraviolet radiation excites electrons in the surrounding gas, with each element emitting a different color of visible light when the electrons return to their relaxed state, much in the way that noble gases work in "neon" signs (different color signs are created by filling the tubes with different noble gases like Argon, Krypton, or Xenon). The red is typically Hydrogen, but may also contain Nitrogen and Silicon, and the green is typically from Oxygen.

Equipment:

-William Optics Zenithstar 73mm FPL-53 doublet APO refractor.

-William Optics Flat73r focal reducer/field flattener.

-SkyWatcher EQ6R-Pro equatorial mount.

-ZWO ASI533MC-Pro color camera with ZWO luminance filter.

-William Optics Uniguide 32mm guide scope.

-ZWO ASI462MC color camera with Antlia 685nm IR-pass filter.

-ZWO ASIair Pro.

-ZWO Electronic Auto Focus.

Pre-processing/Calibration performed in DeepSkyStacker:

-85 120-second lights (gain 0), calibrated with temperature matched darks, flats, and bias frames (60 each at minus 10 degrees Celsius).

-Debayered with Auto Homogeneity Directed interpolation.

-Stacked with Auto Adaptive Weighted Average algorithm.

-2x Drizzle.

-Export to 3-plane FITS.

Post-processing performed in Siril:

-Crop.

-Background Extraction.

-Photometric Color Calibration.

-Arcsinh Transformation.

-Histogram Transformation.

-Export to TIFF.

Final image adjustments performed in GIMP:

-Selective blur on bright stars to reduce CA (Select by color, grow, feather, gaussian blur)

-Histogram adjustment (Levels).

-Fine tune colors (Curves, Hue-Saturation, Saturation).

-Export to PNG.

Shot from my light polluted back yard (Bortle 6-7) under a 33% illuminated waxing crescent Moon.