Data pre-processing steps, applied to a single order: (a) raw spectra, (b) cleaned and blaze corrected spectra, and (c) residual spectra after division by the median spectrum and subtraction of the SYSREM model (shown weighted by the uncertainties). We note that the blaze correction does not work well for cloud-affected frames, resulting in some horizontal structure (residuals) in these regions (the last two panels). However, they only have a minimal impact on our retrievals.