The EXPRES Stellar-Signals Project: Establishing the State of the Field in Disentangling Photospheric Velocities

Measured spectral shifts due to intrinsic stellar variability (e.g. pulsations, granulation) and activity (e.g. spots, plages) are the largest source of error for extreme precision radial velocity (EPRV). The EXPRES Stellar Signals Project (ESSP) is an international research network of scientists working on disentangling stellar signals from true center-of-mass shifts due to planets. We establish the current state of the field through a self-consistent comparison of 21 different methods implemented on the same extreme-precision spectroscopic data from the EXPRES instrument. Method results were compared based on the total and nightly scatter of returned RVs and agreement with other methods. I will give an overview of the project, highlight commonalities between the different methods, and propose recommendations for advancing the field.