S/N as a function of system velocity (v_sys) and Keplerian velocity (K_p) when combining all out-of-eclipse phases for both nights in the barycentric rest frame. The literature values for v_sys and K_p are indicated by the white dashed cross. The maximum S/N is marked by the small circle, and its value is annotated at the top of the plot. Top left: for the fiducial spectral template. Top right: for the neutral iron (Fe) spectral template using the chemical profile assuming equilibrium chemistry. Bottom: the fiducial spectral template without neutral iron.