Location of Photo:
Kolozsvár, EU, Ersatz-Obsi
Date/Time of photo:
Sharpstar 60/330 ED-APO, Lunt CaK B600 LS6CAKMDS2, ASI 178MM (cooled) and EQ3-mod, mountpusher
Most amateur astronomers are somewhat used to seeing prominences on the Sun in the deep red of (or mono or colorized) Hydrogen alpha, but this picture contains only the photons from the narrow band of the Calcium K line. In this nearly UV wavelength, the Sun looks quite unfamiliar in comparison with the Ha image, and it is really challenging to dig out of the raw data (which in this case went to hundreds of terabytes of ser videos) anything beyond the well defined and well lit surface, similar to trying to have nice details on the terminator of the gibbous moon with earthlight.