A rare two back-to-back clear nights in eastern Tennessee enabled about 17 hours to get gathered on this unusually SII-rich target. It isn't very often that the sulfur emission is nearly as intense as the hydrogen emission. The SHO combination formula explained at
The Coldest Nights' website. It applies dynamic weighting factors that are functions of the spatial intensities of the three signals being combined to make the RGB image. The formulas that I used were:
- R = (Oiii^~Oiii)*Sii + ~(Oiii^~Oiii)*Ha
- G = ((Oiii*Ha)^~(Oiii*Ha))*Ha + ~((Oiii*Ha)^~(Oiii*Ha))*Oiii
- B = Oiii
I'm not certain if these expressions are optimal for these particular data, but like what I saw without further tweaking, so I finished the rest of the process. It will be interesting to explore how changing this up a bit affects the results, but that will be for another day.
Dec 12 & 13, 2021
SII: 5.8 h
Ha: 5.4 h
OIII: 6.4 h
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