Reducing brightness distributions to unidimensional parameters. Marginal PPDs (68%-confidence intervals) of the dayside barycenter brightness peak localization for the Γ_SH,1 and Γ₂ brightness models. A comparison with the marginal PPDs of the brightness peak localization (Fig. 9b) shows the reduced model-dependence of the dayside barycenter. In particular, it shows a less-extended PPD for the Γ₂-model barycenter; because this extension for the brightness-peak-localization PPD emerges from the model wings, weighted by the dayside barycenter. In addition, it shows the shift and slight shrinking of the Γ_SH,1 PPD that reflect the barycenter weighting based on to the geometrical configuration at superior conjunction; map cells closer to the substellar point have more weight.