Reproduction of the m _F322W2 vs. m _F115W − m _F322W2 CMD of Figure 4 zoomed in around the bottom of the MS of 47 Tucanae (panel (a)). The aqua line is the blue boundary of the MS and is used to derive the m _F322W2 vs. δ(m _F115W − m _F322W2) verticalized diagram shown in panel (b). The red and blue lines are the best-fit isochrones for MS stars with [O/Fe] = 0.4 and [O/Fe] = −0.1 dex, respectively (Dotter et al. 2008; Milone et al. 2023a). Panel (c) illustrates the δ(m _F115W − m _F322W2) histogram distributions for stars in six F322W2 magnitude intervals and the corresponding kernel-density distributions.