Top: Hα emission EWs across the full line (i.e. core plus wings) for ρ Oph Ab folded with the rotational phase. The dashed line indicates the continuum. The solid curve shows a harmonic fit. Middle: 〈B_ɀ〉 measurements. The dashed line shows the magnetic null. The solid curve shows a harmonic fit. Bottom: K2 light curve adjusted to remove dilution from Aa, B, and C. Phase-binned data are shown by purple squares. Red and green curves show CBO-RRM models with τ_K = 0.1 and 0.06 respectively.