Simulated data (Z = 3, C/O = 0.55, no cloud) and CRIRES+ data of night 3, for a section of order 14. Top row: simulated data with deformation matrix and noise matrix removed. The ‘well’ around orbital phase 0 is due to the modelled transitting effect. The spectral lines of the planet’s atmosphere can be seen within the ‘well’ as faint dark traces. Middle row: simulated data, including the approximated deformation matrix and the modelled noise matrix. Bottom row: real CRIRES+ data, for comparison. The white pixels are pixels masked during the Polyfit preparing pipeline and the trimming (see Sec. 4.2 of the observations). The spectra are represented in arbitrary units.