Results of modelling the photometric and spectral time series of SN 2005cs. Left: Gaussian process light-curve fits for 2005cs in the various bands. The dashed grey lines denote the epochs at which a spectrum was taken that was included in our sample. The epochs were measured with respect to MJD 53548.73. Right: the spectra and their emulator fits for the various epochs for an assumed reddening of E(B − V) = 0.03 mag. The grey bands indicate the telluric regions and the sodium band that were masked for the fitting.