The mean photon energy from the source in keV. This is set as a dynamic default by the program according to the following recipe.
XRT - energy = 0.2 keV
WFC - S1 = 0.15 keV
- S2 = 0.09 keV
- P1 = 0.065 keV
- P2 = 0.02 keV
These values can be overridden on the command line.