The radial intensity profile D(r/R) as a function of the sky-projected distance r from the stellar centre (R is the stellar radius). As in all calculation in this paper, . The solid line shows the effect of limb darkening D(r) = L_D(u₁,u₂,μ)/(1 − u₁/3 − u₂/6) that – multiplied by k² – is directly proportional to the light loss during a transit. The dashed lines show the tolerable ranges: between these lines the radial intensity distribution profile will produce a radius ratio k that is in the tolerance range of ±5%. The dotted line is an example of an acceptable radial intensity distribution profile with u₁ = 0.82,u₂ = −0.16, while the dot-dashed line is with u₁ = 0.02, u₂ = 0.6.