Comparison of the cross-correlation signal-to-noise ratio (S/N) for atmospheres with varying compositions and metallicities. Top: CCF in terms of S/N for different abundances or the equivalent Mean molecular weight. It compares three different injected models with the presence or absence of TiO and VO. The bottom plots give CCF examples for comparison of the planet’s Keplerian velocity vs the line-of-sight velocity map. It shows different levels of significance for different abundances. Below them is a plot of a row in the injected planet velocity from the CCF velocity map.