Time evolution of the features and PCA performance for the target (DES15C2eaz, Type II SN). We use the same color scheme as Figure 12. The exposures shown in Figure 13 correspond to the fourth (low teff) and fifth (regular teff) exposures here. We note that for some exposures the number of sources drops to one after the flag filtering, and accordingly, we set the quantiles to 1 and skip the coefficients if that source is the target. All feature quantiles drop when the source is faint. The feature Nos. 2, 3, 8, 9, 10, 13, and 14 are sensitive to the weather. Feature No. 3 is less effective than the others, as it has smaller 〈c _i 〉 (we use red text when ﹩\langle {c}_{i}\rangle \lt 0.5/\sqrt{{N}_{f}}﹩). The EVR drops as the star gets dimmer. Similar to Figure 12, the q _P is higher than the average quantile (gray curve) except at low S/N. Also, at the last point q _P > q ₀, indicating that PCA has the potential to perform better selection than just using the flux S/N only.