KS integration (from Kelvin-Stokes integration) solves for mutual photometric effects produced by planets and spots allowing to analyze planetary occultations of spots and spots regions.
It proceeds by identifying integrable and non integrable arcs on the objects profiles and calculates analitically the solution exploiting the power of Kelvin-Stokes theorem.
The method provides the solution up to the second degree of the limb darkening law.
KS integration is Free Software you can download the latest version from the
The Sun today, SOHO SDO/HMI