A GPU code for finding microlensing critical curves and caustics

ABSTRACT Advancements in analyses of caustic crossing events in gravitationally microlensed quasars and supernovae can benefit from numerical simulations which locate the caustics in conjunction with the creation of magnification maps. We present a Graphics Processing Unit code which efficiently solves this problem; the code is available at https://github.com/weisluke/microlensing/. We discuss how the locations of the microcaustics can be used to determine the number of caustic crossings and the distances to caustics, both of which can be used to constrain the space of nuisance parameters such as source position and velocity within magnification maps.