Cookie consent

AstroBin saves small pieces of text information (cookies) on your device in order to deliver better content and for statistical purposes. You can disable the usage of cookies by changing the settings of your browser. By browsing AstroBin without changing the browser settings, you grant us permission to store that information on your device.

I agree
Contains:  Crescent nebula, NGC 6888
Getting plate-solving status, please wait...
Crescent Nebula in Synthetic RGB, 


            Frank Kane
Crescent Nebula in Synthetic RGB
Powered byPixInsight

Crescent Nebula in Synthetic RGB

Technical card

Dates:May 25, 2019

Frames: 48x240"

Integration: 3.2 hours

Avg. Moon age: 21.09 days

Avg. Moon phase: 61.16%

Basic astrometry details job: 2709501

RA center: 20h 12' 26"

DEC center: +38° 13' 37"

Pixel scale: 1.113 arcsec/pixel

Orientation: 85.415 degrees

Field radius: 0.443 degrees

Resolution: 2364x1617

Locations: My Driveway, Winter Springs, FL, United States

Data source: Backyard


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 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.



Frank Kane
License: None (All rights reserved)

Sky plot

Sky plot


Crescent Nebula in Synthetic RGB, 


            Frank Kane