My earlier greyscale photo of this nebula was derived from 15 one hour exposures through an H-Alpha filter which were used as the red channel in this color image.. An additional 11 half hour images were taken through an OIII filter for the blue channel. An RGB color image usually uses three different monochrome images. In this case, however, the third color (green) was synthesized from the first two red and blue channels. That saves the time that would be necessary to take images through a third filter and not much is lost since most of the detail in this nebula can be found in the H-alpha and OIII wavelengths. It would be ideal to have a few more images to stack for a smoother image, but this nebula is now in an area of the sky where long imaging sessions are no longer feasible. I may have to wait until next year to obtain more depth in this image.
Astro La Vista Observatory 