We constrain Europa’s tenuous atmosphere on the subsolar hemisphere by combining two sets of observations: oxygen emissions at 1304 Å and 1356 Å from Hubble Space Telescope (HST) spectral images, and Galileo magnetic field measurements from its closest encounter, the E12 flyby. We describe Europa’s atmosphere with three neutral gas species: global molecular (O2) and atomic oxygen (O), and localized water (H2O) present as a near-equatorial plume and as a stable distribution concentrated around the subsolar point on the moon’s trailing hemisphere. Our combined modelling based on the ratio of OI 1356 Å to OI 1304 Å emissions from Roth (2021) and on magnetic field data allows us to derive constraints on the density and location of O2 and H2O in Europa’s atmosphere. We demonstrate that 50% of the O2 and H2O abundances from Roth (2021) are required to jointly explain both the HST and Galileo measurements. The column densities of 1.24*10^18 m^-2 and 1.47*10^19 m^-2 for O2 and H2O, respectively, derived by our analysis however still lie within the uncertainties of Roth (2021). Our results provide additional evidence for the existence of a stable H2O atmosphere at Europa.