Example of the fit carried out by the spectrum synthesis code GAUGUIN for the two CH analysed bands (showed in Table 1) in the solar reflected spectrum of asteroid Vesta, observed by the spectrograph HARPS (Mayor et al. 2003). It was convolved to the X-shooter spectral resolution (R = 10 000). The normalised observed spectrum is shown with open red diamonds, and the solution is indicated by blue crosses. The reference synthetic spectrum grid (from Knowles et al. 2021) is colour-coded according to the [C/Fe] abundance value.