First estimate of the energy response of the UVS detector: the UVS count rate is displayed in blue. It has been fitted by a linear combination of two fluxes directly measured by the CRS instruments, the 133−242 MeV proton channel (black curve) and the 242−476 MeV alpha channel (red curve) plus an exponentially decreasing signal with half-life of 88 yrs assigned to RTG. Both the solar maximum (1999-2003) modulation amplitude and the average 1993−2012 gradient of the UVS signal are slightly stronger than those of the alpha particle parameters and significantly smaller than for the protons, showing that UVS is sensitive to energies only slightly smaller than the alpha energy range. The coefficients are 91% and 9% respectively for the higher (as in the alpha channel) and lower (proton channel). In the graph, the lower energy contribution has been increased by a factor 10 for clarity. The RTG contribution is minor.