The K x-ray satellite spectrum of Ca excited by photons was studied using an LiF(200) plane crystal spectrometer. The satellite energies and their relative intensities were examined in the light of theoretical and experimental data available for electron and proton excitations. The energies were found to be in general agreement with the available data. However, the KL1/KL0 intensity ratio was found to be in agreement with that for electron excitation but not with that for proton excitation. (C) 1998 , Ltd