Synthetic images for a spherically symmetric density model, derived in Saito et al. (1977). Panel a: Synthetic total brightness. Panel b: Synthetic polarised brightness. Panel c: Comparison of the computed FoMo total brightness along the equatorial plane (blue line) with the F-corona brightness curve (dark blue dashed line) from Koutchmy & Lamy (1985) and polarised brightness (red line) with the K-corona brightness curve (dotted maroon line) from Saito et al. (1977).