Using AO telemetry to characterize scintillation for high-precision transit photometry

Abstract

Transiting exoplanets make up the majority of known exoplanet systems, providing invaluable insights into planetary demographics and compositions. Photometric follow-up observations are essential for confirming candidates, refining their orbital and physical parameters, and enabling atmospheric characterization. However, achieving high photometric precision from the ground remains challenging. For bright targets, the limitation is atmospheric scintillation (i.e., intensity fluctuations due to the propagation of light through turbulent atmospheric layers). Although scintillation decreases with increasing telescope aperture, it scales more slowly than photon noise and can therefore remain the limiting factor on large telescopes. We propose a method that uses adaptive optics wavefront sensor telemetry to identify and reject data most strongly affected by scintillation. This will enable us to achieve sub-mmag precision for bright stars (V<10). We present a custom pipeline for characterizing scintillation and preliminary results obtained from pyramid wavefront-sensor data collected with the Subaru Coronagraphic Extreme Adaptive Optics system (SCExAO) on the 8.2-m Subaru Telescope.