Abstract

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). Several methods have been developed to disentangle stellar signals from true center-of-mass shifts due to planets. The EXPRES Stellar Signals Project (ESSP) presents a self-consistent comparison of 21 different methods tested on the same extreme-precision spectroscopic data from EXPRES . Methods either derived new activity indicators, constructed new models for mapping an indicator to the needed RV correction, or separated out shape- and shift-driven RV components. Method results were compared based on the total and nightly scatter of returned RVs, agreement with other methods, and correlation with activity indicators. I will give an overview of the project, the submitted methods, and the final results. This comparison allows me to highlight commonalities between the different approaches and propose recommendations for moving forward.