Wiggle-corrected spectra extracted from the emsm data cube with a spaxel size of 0.1″. Top panel: LBQS 0302−0019 spectrum integrated over an aperture of r = 0.5″ (orange curve), in comparison with the spectrum of the brightest spaxel, after the wiggle subtraction (blue curve). Both spectra are normalised to 1 for visualisation purposes. The residuals are reported in grey and are obtained as the difference between the blue and orange curves (see Fig. 5 for details). Bottom panel: Residuals obtained from the eight spaxels closest to the brightest one. The most significant residuals are found at the position of the brightest emission lines: they are not due to the wiggles, but to the line profile variations.