Illustration of the mapping of the proton precipitation between ionospheric altitudes and the Vlasiator simulation domain. The coloured cells in the MLAT–MLT ionospheric grid match the dots inside the Vlasiator domain at 5.5 R_E distance from the Earth’s centre, where the precipitating fluxes are evaluated. The dashed (solid) grey lines joining them represent geomagnetic field lines consisting of an ideal geodipole field with external contributions given by the T01 model inside (outside of) the inner boundary of the Vlasiator domain at r = 4.7 R_E.