A Planetary Nebula, NGC 246, in constellation Cetus.

Luminance is mixed from Broad band Luminance and H-alpha. Colors are mixed from narrow band channels,
Natural color composition from the emission of ionized elements, R=80%Hydrogen+20%Sulfur, G=100%Oxygen and B=85%Oxygen+15%Hydrogen to compensate otherwise missing H-beta emission. This composition is very close to a visual spectrum.
Technical details:

16" RCOS ja Apogee U9000 camera.
Lum +H-a, O-III and S-II combo. An Australian remote telescope
4x600s for the Luminance
3x1200s H-alpha
1x1200s O-III
1x1200s S-II
Dark, Bias and Flat calibrated.
Raw data is shared by Petri Kehusmaa and J-P Metsavainio

Processing workflow:
Image acquisition, MaxiDL v4.xxx
Stacked and calibrated in CCDStack.
Deconvolution with a CCDSharp, 30 iterations, added at 50% weight.
Levels, curves and color combine in PS CS3.