Illustration of the procedure to derive the metallicity distributions of 1G stars in 47 Tucanae. Top panels: comparison between the observed Δ_{C F275W, F336W, F438W} vs. Δ_{F275W, F814W} ChM for 1G stars within the central field (red points in panel a) and the ChM of simulated 1G stars (panels b and c). The stars in the yellowish ChM in panel b have an iron abundance of [Fe/H] = −0.94, while those of the reddish ChM have [Fe/H] = −0.32. The ChM of panel c represents the best-fitting simulation. The number of simulated 1G stars is about five times larger than the observed stars. Bottom panels: histograms of the observed Δ_{F275W, F814W} (Δ_{F606W, F814W}, Δ_{F606W, F115W}) distributions inferred from 1G stars within the cluster center (panel d), fields A, B, and C (panels e, f, and g, respectively). In each panel, the red line corresponds to the simulated 1G Δ_{F275W, F814W} (Δ_{F606W, F814W}, Δ_{F606W, F115W}) distribution that provides the best match with the observed data.