Central flash resulting from a finite stellar radius r_* projected at the body distance, in the geometrical optics regime. The plot has been generated by used Eq. (57) (blue part) and Eq. (61) (red part). The functions E and G are given in Eq. (59) and Table F.1. The values along the horizontal axis have been normalized to the stellar radius r_*, while the flux along the vertical axis has been normalized to its peak value 4(R/r_*)φ_⊥(0) (Eq. (62)). The two bullets show the values x/r_* = ±1.14 where the flash reaches half of its maximum value. The dotted line shows the diverging flash profile produced by a point-like star in the geometrical optics approximation (Eq. (9)).