Abstract

The High Accuracy Radial velocity Planet Searcher-3 (HARPS3) is being developed for the Terra Hunting Experiment, a 10-year observing campaign to conduct nightly observations of a carefully selected group of solar-like stars to detect long-period, low-mass exoplanets. The goal is to achieve extremely-precise radial velocity (EPRV) measurements at the level of 10 cm/s to enable the detection of an Earth-twin. Attaining this precision requires a deep understanding of all error sources: instrumental systematics, astrophysical noise, and data reduction algorithms.

To address the latter, I have developed a novel method to test the data reduction pipeline (DRP) using synthetic data. Rather than attempting to replicate the instrument’s response exactly, the method is designed to systematically probe the DRP ’s performance, identify potential biases, and validate the reduction algorithms. By injecting known inputs into the DRP and tracing their propagation, I can control all aspects of the data, test specific algorithms, and verify the accuracy of the reduction products. The aim is to use simulated data to identify systematic biases and inaccuracies that could impact EPRV measurements.

In this talk I will present my work, currently in preparation for publication, describing how I simulate the data and discussing the first results of passing the synthetic echellogram through the DRP . This approach provides a framework to assess the performance of HARPS3 during commissioning and early operations – when it comes on-sky in late 2025 – enabling us to identify issues and refine data processing techniques.