Observed spectra matrices at different steps of the analysis for a short wavelength range in order 41. We plot wavelength along the horizontal axis and the time series of spectra along the vertical axes. Top panel: matrix of spectra as provided by the CARMENES pipeline. Upper middle panel: normalised and masked spectra ready for the telluric and stellar removal process with SYSREM. Bottom middle panel: matrix of residuals after the first iteration. At this point the telluric residuals are still visible. Bottom panel: matrix of residuals after the tenth iteration. The telluric residuals are almost completely removed.