Light curves for a two-sphere test, computed for different discretisations: 42, 272, and 1123 nodes. The precision is of the order < 0.1 mmag, even for the coarse discretisation. Tiny changes of the derivative are related to subsequently eclipsing or occulting large triangles with different normals. The magnitude in V band is computed for the effective wavelength λ_eff = 545 nm and the effective passband ∆_eff = 85 nm.