Vertically emergent intensity in the core of the 525.0 nm line as a function of x-position, counted from the FS center (i.e. from the horizontal axis of Fig. 1 cutting across the FS). The plotted curves were calculated with two different angle sets, where solid lines indicate the set of 27 (inclination)  ×  2 (azimuth) rays per octant and dashed lines the standard set A6 of the RH code with 6 rays per octant. The thin vertical line indicates the nominal FS boundary (R = 100 km), which was reached at the τ_c = 1 level in the field-free atmosphere (at the same position as the rightmost vertical line in Fig. 1).