Shock-induced spectral energy distribution in η Car from 1 keV to 1 PeV. The data (black) are from NuSTAR (Panagiotou & Walter 2018), Swift/BAT, INTEGRAL, and Fermi-LAT. The red points are the H.E.S.S. measurements obtained close to periastron. Green points show a 50-hour simulated observation by the CTA at periastron. The blue line shows the spectrum that might be expected at apastron with a lower energy cut-off and obscuration. The system geometry can be constrained by a shift of the obscuration peak throughout the orbit, which is not taken into account here. The yellow dotted line is the 50 h CTA point-source sensitivity (5σ per bin of ΔE/E = 0.2).