The best correlations between absolute BCG+ICL brightness M_BCG+ICL[g′ mag] (upper panels) or the absolute brightness of the ICL-only M_ICL [g′ mag], dissected via the surface brightness threshold of 27 g′ mag ﹩{M}_{\mathrm{ICL}}^{\mathrm{SB}27}﹩ (lower panels; method b) and host cluster parameters. Each row shows a different host cluster parameter: (1) gravitational mass ﹩{{ \mathcal M }}_{{\rm{g}}}\,[{M}_{\odot }﹩], (2) integrated absolute brightness of all satellite galaxies (excluding the BCG+ICL) M_sat [g′ mag], (3) velocity dispersion of the satellite galaxies σ_C [km s⁻¹] (taken from Lauer et al. 2014), (4) gravitational radius r_g [kpc], (5) mass phase-space density ﹩{f}_{{{ \mathcal M }}_{{\rm{g}}}}[{M}_{\odot }﹩ kpc⁻³ km⁻³ s³], and (6) number phase-space density of the satellite galaxies f_s [kpc⁻³ km⁻³ s³]. The Pearson coefficient for each correlation is given as a black label and its error (calculated using 10,000 bootstraps) as a gray label. The full collection of plots is shown in Appendix B, and the best-fit parameters are listed in Appendix C.