For each potential source, we compute the correlation coefficient between a stacked vector of simulation predictions at all sensor locations and a stacked vector of the corresponding background-corrected CMS observations. This results in a correlation value for each potential source for all identified emission events. For each emission event, the source with the highest positive correlation is taken to be the localization estimate for that event. Correlation coefficient is a natural choice for the evaluation metric used in this step, but we also tested a custom metric that rewards spike alignment and penalizes spike misalignment. We discuss these metrics in more detail and present a sensitivity study in Section S2 of the SI file.