Analysis of Europa’s H exosphere signal: (a) H exosphere brightness in the disk center from the fitted exosphere profiles (Eq. (3)) for each visit. (b) Solar Lyα flux (black asterisks) measured at 1 AU near the observation date (see text). The inverse of the squared heliocentric distance of Europa (orange triangles, in unit 0.01 AU⁻²) indicates the scaling of the flux used for calculating g-factors. (c) g-factors for resonant scattering of the sunlight (blue diamonds), of the IPH illumination (green) and combined (black). (d) H exosphere vertical column densities from conversion of measured brightnesses. (e) Same as in (d) but plotted against the line-of-sight velocity of Europa with respect to the Earth at the time of the observation. (f and g) Same as (e) but only for visits 2-18 taken in 2012-2015 and for visits 21-29 taken in 2018-2020, respectively. Fitted attenuation profiles for different temperatures of the H in Europa’s exosphere, see text for more information. The 1999 visit is shown in grey in (f) and (g) for comparison.