MASSCW priors allow for a quantification of prediction uncertainty. Here we show both an absolute and a relative measure of spread for the single-direction specific intensity distributions (i.e. marginals) at ν_obs = 150 MHz. For each direction, we discard data outside the 1–99% percentile range. Top: marginal standard deviation (absolute uncertainty), which closely resembles the marginal mean of Fig. 9a. Bottom: marginal standard deviation over mean (relative uncertainty), which reveals an inverted trend.