Illustration of the two approaches to candidate priors P(O) assumed in this manuscript: identical and inverse. The former assumes an identical prior for every galaxy with θ_i < 10ϕ or within the 99.9% localization error of the FRB. The latter adopts the inverse of the estimated chance probability P^c of these galaxies, which is equivalent to asserting the prior is proportional to the integrated probability that the other sources are all chance coincidences.