IUVS limb observations for the emission intensity profiles of Ly-α and CO₂ ionization and dissociation emissions during orbits 6937, 6938, and 6939. Each panel contains 12 profiles from 12 limb scans indicated by varying color intensities. MAVEN trajectories during the H-ENA penetration event within (b) ($X_{\text{MSO}}-\sqrt{Y_{\text{MSO}}^2+Z_{\text{MSO}}^2}$) coordinate plane are plotted in units of Martian radii (R_M). In Fig. 4b, the solid magenta and blue lines represent the MAVEN orbital trajectories 6938 and 6939 respectively, recorded during the H⁺ and H⁻ event from 16:35 to 16:45 UT on 24 April, 2018. The dashed red and blue lines indicate the BS and IMB, which were calculated using the model of (Trotignon et al. 2006).