Best-fit component column densities for (b) molecular oxygen (O₂) and 1σ detectability thresholds for (a) atomic oxygen (O) and (c) water (H₂O). The model used the median density of 158 cm⁻³ (F. Bagenal et al. 2015), scaled according to the nominal System III longitude-dependent ambient electron density shown in Figure 8(b). For O₂, the solid gray horizontal line shows the geometric mean and the gray shaded region shows the uncertainty in the mean. The dashed lines show the standard deviation of the calculated column densities relative to the mean. To calculate the O₂ column density, we weighted the values by their inverse variance. Perceptually uniform colors and symbols (circles, diamonds, and squares) differentiate separate observing nights to allow the reader to evaluate the goodness of fit on a night-to-night basis (see the legend in Figure 2).