Celestial hemisphere:  Northern  ·  Constellation: Cygnus (Cyg)  ·  Contains:  Crescent nebula  ·  LBN 203  ·  NGC 6888  ·  Sh2-105
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Crescent Nebula in Synthetic RGB, Frank Kane
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Crescent Nebula in Synthetic RGB

Getting plate-solving status, please wait...
Crescent Nebula in Synthetic RGB, Frank Kane
Powered byPixInsight

Crescent Nebula in Synthetic RGB

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Description

The Crescent Nebula (NGC 6888) imaged with narrowband filters from a suburban driveway, converted to RGB using an algorithm that tries to recreate its natural appearance from narrowband data. It's a way to beat light pollution while still getting fairly natural-looking colors. The details are at http://boldly-going.com/2019/05/21/beating-light-pollution-with-a-new-synthetic-rgb-algorithm/ and you'll also find the larger image this was cropped from there.

For this image I derived a slightly different RGB mapping that takes into account the fact that my filters are narrow enough to exclude the second O3 emission line, and synthesizes it as well:

R = 0.5*Ha + 0.5*SII

G = 0.695*OIII + 0.094*Ha

B = 0.411*OIII + 0.1*Ha

It didn't make much of a visual difference, but in theory it's a little bit closer to reality.

Other processing notes:

- I love Mure Denoise

- OIII and SII data wasn't awesome, so I used Hydrogen-alpha as a luminance channel. Unfortunately this means a faint shell of OIII ahead of the nebula got lost, but the image is significantly sharper as a result.

- I de-saturated everything a little outside of the Crescent itself, to make the stars a little less distracting in the image.

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Crescent Nebula in Synthetic RGB, Frank Kane