We obtained a calcium K-line filtergram
at 19:22 UT; it showed that the activity was occurring somewhere between the Sun's visible surface, or photosphere, and the lower regions of the overlying chromosphere.
Increasing technological developments in solar instrumentation have revolutionize the acquisition of time series of filtergrams
and solar data that enable to follow the evolution and dynamics of solar phenomena, in particular at the finest temporal and spatial scales.
Wear particle analysis or Filtergrams
are undertaken on all transmissions at 2,000 hour intervals.
Observations during the week beginning February 4th revealed striking solar activity in both hydrogen-alpha and calcium-K light, as seen in the photographs or "filtergrams
" reproduced here.