The colors of this target are well represented using a SHO palette except for the nebula surrounding HD 148937 that includes NGC 6164 and NGC 6165 ('the egg'): Ha and Oiii have a strong signal that overlaps if a Ha->G, Oiii->B mapping is used, resulting in a completely greenish nebula.
To better highlight the color contrast a HOO palette, where Ha is mapped to R, is more effective for this area.
Mixing two different palettes in the same image seemed to me like unneeded overprocessing at first; but colors are used to highlight physical phenomena and in the same field of view there could be objects that have a completely different dynamic and thus need a different presentation.
Moreover we're already mixing different palettes when we substitute the RGB stars into a NB image (that I did for this image as well).
I still used a SHO palette for the main part of the image.
The total exposure time of the two panels is 105.5 hrs:
Ha: 17.1 hrs + 18.2 hrs
Oiii: 16.1 hrs + 16.3 hrs
Sii: 13.8 hrs + 18.0 hrs
R: 1.0 hrs + 1.0 hrs
G: 1.0 hrs + 1.0 hrs
B: 1.0 hrs + 1.0 hrs
Other features in the image:
The egg ( NGC 6164/6165) nebula was identified as planetary nebula but ESO released recently (11 April 2024) an
interesting study that introduces a new interpretation of the origin of the nebula.
"
... there were originally three stars in the system, until two of them clashed and merged. This violent event created the surrounding cloud and forever altered the system’s fate."
Above: possibly some dust structures blown away by stellar wind.
Below: a crop of the 'fighting dragons'.
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