The Extreme Stellar Signals Project

The Extreme Stellar Signals Project (ESSP) is an international research network of scientists developing methods for mitigating stellar signals. With our first round of work, we established 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. This talk will introduce the second round of comparisons, which makes use of contemporaneous Sun-as-a-star observations taken by HARPS, HARPS-N, EXPRES, and NEID. I will share lessons learned from comparing contemporaneous data across instruments and discuss strategies for combining data from different instruments. I will conclude with the potential and limitations of this combined data set for testing mitigation methods.