A public dataset of Ariel simulated observations for developing exoplanetary atmosphere data reduction pipelines

arXiv:2605.03719 · astro-ph.EP, astro-ph.IM · Submitted 2026-05-05 · Read on arXiv

Lorenzo V. Mugnai, Kai Hou Yip, Andrea Bocchieri, Andreas Papageorgiou, Virginie Batista, Orphée Faucoz, Angèle Syty, Tara Tahseen, Enzo Pascale, Ingo Waldmann

astro-ph.EP, astro-ph.IM

Submitted: 2026-05-05

Comments: 22 pages, 26 figures. Accepted for publication in RASTI

Code: https://github.com/arielmission-space/ExoSim2-public

License: http://creativecommons.org/licenses/by/4.0/

The gist: Detecting and characterising exoplanet atmospheres remains challenging because atmospheric signals can be comparable to residual noise and instrumental/astrophysical systematics.

Terminology

Abstract

Detecting and characterising exoplanet atmospheres remains challenging because atmospheric signals can be comparable to residual noise and instrumental/astrophysical systematics. Spectral features span from a few ppm for small planets up to about 10 cubed ppm for warm/hot giants, while high-quality JWST time-series spectroscopy typically reaches about 10 -- 50 ppm (occasionally about 100 -- 200 ppm in the presence of stellar variability or stronger systematics), making correlated noise across temporal and spectral dimensions a key limitation. With JWST delivering an increasing volume of high-precision transmission spectra, and Ariel set to extend this to a homogeneous survey of about 10 cubed exoplanet atmospheres, robust benchmarking resources with known ground truth are essential to develop and validate data-driven (including ML-based) detrending approaches. As a major step towards this goal, we use ExoSim2 and TauREx to generate one of the most comprehensive public datasets based on the current payload design of the ESA Ariel mission, specifically intended to benchmark detrending algorithms. We also provide a deep neural network baseline for time-series reduction, and use it to highlight the limitations of ML based detrendng methods, i.e. the risks posed by dataset shift when observed distributions diverge from those of the training set, a scenario likely to arise in real observations. This dataset is featured in the Ariel Data Challenge 2024 on Kaggle and has been field-tested for robustness and simulation fidelity. By making these resources publicly available, we aim to support the community in developing, comparing, and stress-testing scalable and reliable methods for exoplanet transmission spectroscopy.

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