Estimate of the number of WDs in each population. (a): Verticalised m_F606W versus Δ_{F606W − F150W2} CMD. The magnitude interval 25 < m_F606W < 26.7 adopted is highlighted in cyan. The two WD groups are shown in blue (bWD) and red (rWD), with their respective numbers of stars indicated. The uncertainties correspond to Poisson errors. (b): Histogram of the Δ_{F606W − F150W2} distribution for stars within the cyan-shaded region of panel (a). The best-fit double-Gaussian model is plotted in grey, with the individual components in blue and red. The fractions of stars in each component are derived from the Gaussian areas, and the corresponding σ values are reported.