Foukal, P; Bertello, L; Livingston, W. C; Pevtsov, A. A; Singh, J; Tlatov, A. G; Ulrich, R. K
(Springer, 2009-04)
Spectroheliograms and disk-integrated flux monitoring in the strong resonance line of Ca ii (K line) provide the longest record of chromospheric magnetic plages. We compare recent reductions of the Ca ii K spectroheliograms ...