Sample CES spectra illustrating data quality. Continua are shifted by  ±0.3 from unity for visibility. Blue dash-dotted vertical lines indicate spectral lines used for analysis. Upper panel: data set A. Upper black spectrum: sunlight reflected from Jupiter’s moon Ganymede; lower red spectrum: HD 68456 (F6V, vsini ≈ 10 km s^-1). Lower panel: data set B. Upper black spectrum: inactive and slow rotator 61 Vir (G6V); lower red spectrum: active and faster rotator 59 Vir (G0V, vsini ≈ 6.5 km s^-1).