republic: A variability-preserving systematic-correction algorithm for PLATO’s multi-camera light curves

Abstract

Abstract Space-based photometry missions produce exquisite light curves that contain a wealth of stellar variability on a wide range of time-scales. Light curves also typically contain significant instrumental systematics – spurious, non-astrophysical trends that are common, in varying degrees, to many light curves. Empirical systematics-correction approaches using the information in the light curves themselves have been very successful, but tend to suppress astrophysical signals, particularly on longer time-scales. Unlike its predecessors, the PLAnetary Transits and Oscillations of stars (PLATO) mission will use multiple cameras to monitor the same stars. We present republic, a novel systematics-correction algorithm which exploits this multi-camera configuration to correct systematics that differ between cameras, while preserving the component of each star’s signal that is common to all cameras, regardless of time-scale. Through simulations with astrophysical signals (star spots and planetary transits), Kepler-like errors, and white noise, we demonstrate republic’s ability to preserve long-term astrophysical signals usually lost in standard correction techniques. We also explore republic’s performance with different number of cameras and systematic properties. We conclude that republic should be considered a potential complement to existing strategies for systematic correction in multi-camera surveys, with its utility contingent upon further validation and adaptation to the specific characteristics of the PLATO mission data.