Aggregated residuals (blue) due to NLO contributions in Shapiro and aberration delay, shown in the orbital phase ψ. Residuals are re-scaled by (1 + e_T cos θ)⁻¹ to account for secular variations in amplitude due to the precession of periastron. The black curve indicates the fitted q_NLO (see Table 2) with the 2σ range shown by the grey shaded areas, which agrees very well with the theoretical prediction indicated by the red dotted line.