and I have been battling with getting the narrowband colors we want with our CCD for a while now. The problem was that many of the images we've seen that claim to be using the HST color palette, in fact are not. Anyway, while narrowband image combinations aren't that simple, I wanted to show the different between the true HST-SHO palette and what we often actually see in shared narrowband images.
NGC6188 in the southern constellation Ara is a current work in progress right now, displayed using two different color palettes. The partially-processed image on the left is using the true HST-SHO (SII-Ha-OIII/R-G-B) palette, while the image on the right is using a blended-but-mostly-pure OIII-Ha-SII/R-G-B, not the HST palette.
The problem is, the palette/channel combination used on the right is often shared online and incorrectly called the "HST" palette, which had us pulling hair out trying to get the right colors. We personally like the modified palette better...but it's false color anyway, so do what you like. :)
Note I'm trying to not start a petty argument about what narrowband images are supposed to look like, but just informing anyone else who is struggling to get the "right" color in their narrowband images.
Good luck! #astrophotography #astronomy #narrowband #nebula #space #photography