it’s time to update my version of the rosette nebula for 2021. this was one of the first targets I captured after astromodifying my DSLR last year. I had a series of before and after and it was obvious the astro-mod was worthwhile. However, I’ve been getting such detailed images with my cooled mono camera with filters that I’ve been looking forward to seeing a big update for this year.
I was able to capture about 14 hours of data across Ha, Sii, and Oiii narrowband channels. However, upon inspection, I had to toss a third of the Oiii data due to running into the treeline in early morning hours.
a second change this year was in the PixInsight processing. the key difference in processing was to create a luminance layer out of the Ha data and apply that to SHO mapped RGB starless image. I’ll show a few of the key steps below, but first the imaging session details:
imaging session details:
I’ve mentioned the general flow above, but share a few key steps along the way for reference:
the 3 channels are processed individually in linear state as usual with DBE and light multiscale linear transformation noise reduction:
Next, the 3 channels are masked and boosted with exponential transformation before going non-linear.
Now that the 3 channels are stretched to non-linear with histogram transformation, the stars are removed with Starnet.
the starless non-linear channels are combined using pixelmath to form the starting point for the SHO mapped RGB image processing:
Finally after several more detailed processing steps to further reduce noise and some light sharpening around the structures the stars are brought back in by applying the Ha as a luminance layer via LRGBCombination: