The Sixth Workshop on Extremely Precise Radial Velocities (EPRV 6)
30 June - 03 July 2025, Porto, Portugal
Splinter Sessions
Session 1: Sun-as-a-Star Part I: Accessing and Working with EPRV Solar Datasets
Organizers: Ryan Rubenzahl, Khaled Al Moulla, Lily Zhao, Megan Bedell
Abstract. Data from five operational EPRV solar feeds (and as many more on the way), with baselines stretching two to ten years, provide a powerful means to characterize both the stellar and instrumental error budgets. Part I of this splinter session will introduce these datasets (i.e. HARPS, HARPS-N, NEID, EXPRES, and KPF) as well as heliophysics resources relevant for EPRV (e.g. SunPy and SolAster). This will be followed by a hands-on interactive portion that will empower attendees to access and work with these datasets.
Session 2: Planets around young stars
Organizers: Louise Dyregaard Nielsen, Oscar Barragan, Matt Battley, Serena Benatti, Ilaria Carleo, Felipe Murgas, Matteo Pinamonti, Alejandro Suarez Mascareño
Abstract. Young planetary systems are valuable targets for understanding planet formation and evolution. Young planets, however, remain elusive due to their active host stars that pose challenges for EPRV work. RV follow-up is most cases the bottleneck towards fully characterising young systems. In this splinter session we will discuss ongoing efforts to characterise young systems with a focus on both science and methodology; including mass measurements as an empirical anchor for planet formation theories, planet demographics, stellar physics and characterisation of young stars, tracing planet evolution over time, use of Gaussian processes, RV extraction methods and observation strategy.
Session 3: Sun-as-a-Star Part II: Benchmarking Stellar Variability Mitigation Methods
Organizers: Federica Rescigno, Khaled Al Moulla, Lily Zhao, Megan Bedell
Abstract. The high cadence and signal-to-noise ratio of disk-integrated, high-resolution solar spectra yield an unmatched dataset for developing data-driven methods that separate stellar variability and planetary Doppler shifts. Part II of this splinter session will feature contributed talks presenting the latest efforts at combating different types of stellar variability using Sun-as-a-star data. Afterwards, we will initiate a discussion with the community regarding future rounds of the Extreme Stellar Signals Project (ESSP) data challenges aimed at applying and comparing recent developments in stellar variability mitigation techniques on various uniformly processed Sun-as-a-star datasets.
Session 4: Expanding the Role of Photonic Technologies on Extremely Precise Radial Velocities
Organizers: Francisco J. Pozuelos, Kalaga Madhav, Pedro J. Amado
Abstract. In this splinter session we aim to examine how emerging photonic tools—including single- and multi-mode photonic lanterns and photonic spectrographs—could shape next-generation exoplanet and stellar instrumentation. By convening experts from photonics, instrumentation, and stellar and planetary science at EPRV6, we aim to identify integration pathways and address technical and adoption challenges. The session will feature concise presentations and moderated discussions and will inform a subsequent white paper. We seek to establish a strategic roadmap guiding the development and implementation of these photonic solutions in the evolving, dynamic EPRV landscape.
Session 5: Gaussian processes and deep learning for stellar activity mitigation
Organizers: João Faria, Manuel Perger, Guillem Anglada Escude
Abstract. Probabilistic and machine learning methods, like Gaussian processes and deep learning, have led to substantial improvements in the mitigation of stellar activity in precise RVs. But their physical interpretation is not always obvious and they can suffer from issues like overfitting or difficulties in model definition and comparison. This splinter will explore the application of these methods in the EPRV context, with the objective to develop a better understanding of best practices for future RV datasets and surveys.
Session 6: Following the flows: observations of stellar supergranulation across spectral types
Organizers: Niamh o’Sullivan, the EPRV RCN Standard Stars Group
Abstract. In recent years, supergranulation has emerged as one of the primary obstacles to detecting Earth-twins in the EPRV regime, despite advances in analysis techniques and instrumentation. Its time scales (8-24 hours for Sun-like stars) are difficult to observe with a single ground-based telescope, prompting the EPRV standard star group to develop a multi-instrument observational approach. This splinter session will gather experts to discuss current and planned observations to detect and mitigate supergranulation, both from the EPRV standard stars group and other initiatives, share results, and plan the next phase of observation proposals to address this challenging issue.
Session 7: Aiming accurate wavelength calibration
Organizers: Francesco Pepe, Gaspare Lo Curto, Christian Schwab
Abstract. Accurate calibration is critical for long-term radial velocity measurements and is needed to fully remove the instrumental signature. In order to detect Earth-mass planets on 1-year orbits around solar-type stars, the radial-velocity measurements must be perfectly repeatable at time scales of several years and thus insensitive to possible instrumental drifts and changes of the instrument profile, which can be ensured only by absolute calibration. The problem of absolute calibration is however not solved and raises several questions that must be tackled: What calibration sources must be used? How can we control and/or measure the instrumental profile? How can we extract information and remove residual instrumental signatures?
Session 8: A Community Developed EPRV Data Standard
Organizers: Jennifer Burt, EPRV Data Format Team
Abstract. Little is known about how specific hardware and software approaches adopted by modern EPRV instruments flow down to the RVs and stellar variability metrics they produce. Our team has defined an EPRV data standard and ‘translator’ tools to facilitate the cross-instrument comparisons necessary to reveal these impacts. We will share the first version of the data standard which covers everything from order-by-order spectra to derived radial velocities and invite feedback/suggestions from attendees. We will also provide templates for data ‘translators’ that attendees can build off of and lay the groundwork for coordinated comparisons of stellar data between EPRV instruments.
Session 9: The RV follow-up of PLATO candidates: will we be able to weigh Earth analogues?
Organizers: Luca Malavolta, PLATO Stellar Variability Working Group leaders + Top-level Working Packages leaders
Abstract. The RV follow-up for exoplanetary characterisation is an integrated part of the PLATO mission. To this end, the PLATO Stellar Variability Working Group (PSVWG) was formed to coordinate and homogenise the stellar activity treatment across the different areas of PLATO. In this splinter, we will discuss with the community the recent developments in PLATO regarding activity mitigation in simultaneous photometric and spectroscopic time series and the efforts to build a comprehensive exoplanetary modelling toolkit. We aim to involve the entire community in understanding the state-of-the-art developments relevant to the prioritisation and mass measurement of PLATO planet candidates.
