Robustness of the UHECR secondary electron synchrotron model fit to the spectrum of 1ES 0229+200, for different UHECR injection spectrum parameters. Here nG has been assumed. Top panel: model prediction for E_max = 10^20.5 eV (red dotted line) and E_max = 10²¹ eV (green solid line). Bottom panel: model prediction for injection spectral index α = 2 (blue dotted line) and α = 2.3 (green solid line).