Peter thanks for your feedback - perhaps you too were channelling Ansel Adams when you chose the 'natural' colour palette for
this image? 
Mike Sidonio has produced a lovely, 'natural'
HaRGB image of BBW56.
However, for Narrowband imaging it appears you mey be unfamiliar with the elemental composition of this object.
See
Phillipe's image from Chile or
Matthew Ludgate's from NZ which clearly show the strong presence of the S2 signal, running almost in parallel with the HA.
Following the traditional HST colour palette, when one assigns Ha to green, O3 to Blue and S2 to red - in this instance you'll get a strong yellow coastline from the overlapping blend of Ha & S2.
ie: Green & Red = Yellow.
In this instance, the colours were assigned to classic HST palatte, not assigned arbitrarily as you have incorrectly assumed.
FYI, I've attached the straight HST version of mine, before I tweaked the green to taste with selective colour in PS.
I too enjoy Ansel Adam's work, and Warhol's - as they are both very fine artists working with differing styles, may I suggest the world is big and diverse enough for us to appreciate both.
