Example of a GPs fit to the light curves of ZTF18aaqfziz (SN 2018bhp), a SN with average sampling (see Fig. 1 from Rigault et al. 2025a). Top: Light curves in flux space for g, r, and i-band, as a function of time (in observed days), colour-coded as described in the legend. The solid lines show the GP fits, as described in the text, with shaded regions displaying the 1σ uncertainty. The vertical dashed line marks the fitted SALT2 time of maximum luminosity in B-band. Bottom: Same light curves and GP fits as above, but in magnitude space (both apparent and absolute), with downward triangles marking non-detections. The symbols correspond to the estimated brightness in each photometric band at various phases (see legends).