Stacking 12 scans, through continuum subtraction and further processing, I managed to reveal some really subtle details on the Sun, clearly showing filaments in Oxygen. Somewhat ironically, on this day, there were no flares, no smudges and no bright prominences, to add to the repertoire of the image presented here. I included AIA 1600, GONG and AIA/SUVI 304 for reference.
I consider it settled: there are filaments in oxygen, in O I 7772, on the disk of the Sun, and a Sol’Ex derivative amateur spectroheliograph can observe them.
