STARRY: Analytic Occultation Light Curves

Understand

We derive analytic, closed form, numerically stable solutions for the total flux received from a spherical planet, moon or star during an occultation if the specific intensity map of the body is expressed as a sum of spherical harmonics.

• Our expressions are valid to arbitrary degree and may be computed recursively for speed.
• The formalism we develop here applies to the computation of stellar transit light curves, planetary secondary eclipse light curves, and planet-planet/planet-moon occultation light curves, as well as thermal (rotational) phase curves.
• In this paper we also introduce STARRY, an open-source package written in C++ and wrapped in Python that computes these light curves.