Prominence body characteristics: (top panelsfrom left to right) Mg II k observed integrated intensity, Doppler shift, and FWHM along slit 12; (bottom panels from left to right) non-LTE model results along slit 12, mean electron density, τ(Mg II k), and τ(H α). The grey areas correspond to pixels where the observed profiles in Mg II cannot be correctly fitted with the grid of profiles derived by the non-LTE radiative transfer code. The red arrows indicate the points in Table 4.