These are the exposure numbers all of the paper’s empirical bounds rest on. Inputs beyond the flux data: lunar surface area (8pi^2 R^2 factor, eq. 4), lunar iron abundance f_Fe = 0.012 (Apollo samples, conservative low end of 4.2-17.2% FeO by weight), geometric cross section sigma = 0.18 A^(2/3) barn, and for the light-cone number, integration over the volume and age of the universe following Hut-Rees (whose flux inputs were subsequently confirmed). Energy scaling of every rate follows the measured power law (e.g. E^-1.7 integrated flux, E^-3.4 for two-flux collision rates).