Extracted spectrum of carbon star 1022334 (same as in Fig. 3, bottom panel) in yellow, shown with the best fit determined with ULySS in blue, using the empirical MIUSCAT spectral library amended with 19 spectra of carbon stars from the X-shooter library. Contrary to the synthetic fit, this fit properly reproduces the CN features, including the sharp band heads, with the exception of the one at ∼5150 Å. What may seem to be noise in the fitted spectra is in fact a forest of molecular lines unresolved at the resolution of MUSE.