rtn-047
Maximizing Rubin’s Scientific Return by Making EDF-S Fully Public#
Recommendation#
Designate Rubin Observatory data in the Euclid Deep Field South (EDF-S) as fully world-public on an ongoing basis, thereby establishing EDF-S as a standing legacy field in the model of COSMOS.
Key Benefits#
Cross-survey science: Makes public the Rubin data required to complete, alongside the already-public Euclid and future Roman EDF-S data, a real dataset that serves as an accessible-scale proving ground for myriad exploratory science opportunities, ahead of committing the effort and resources required for full-scale processing across the full-sky datasets. This unlocks development of the pipelines, infrastructure, and analyses needed for joint survey processing;
AI-ready dataset: Provides the Rubin data needed to develop open, AI-ready datasets on a small scale for exploratory science and validation, both for single-survey and cross-survey science;
New legacy field: Launches EDF-S as the next COSMOS, an open legacy field with decades of fresh discovery potential ahead of it;
Public engagement and education: Gives Rubin a field where it can openly showcase its scientific capabilities and lets educators use real Rubin data in the classroom, without data-rights restrictions.
Public test datasets: Provides a small, representative, fully public dataset for software development and testing, including Git LFS test data for Rubin’s GitHub CI, LSST Science Pipelines, and Rubin Data Access Services.
Scope#
This recommendation is scoped solely to EDF-S, leaving the remainder of Rubin’s proprietary dataset and its data access rights fully intact. The risk to Rubin science is minimal: EDF-S covers only about 23 deg2 of Rubin’s approximately 18,000 deg2 survey area and does not materially affect any proprietary program. The potential upsides, by contrast, are considerable.
EDF-S data products will be made publicly available shortly after the full proprietary Data Release in which they are produced, and will not affect the Rubin Data Release schedule.
Rationale#
The Euclid Consortium, Rubin Observatory, and NASA’s Roman Space Telescope all plan to observe the 23 deg2 Euclid Deep Field South (EDF-S) to a combined depth and cadence beyond any single survey’s individual wide-area program. A 2022 white paper ([Guy et al., 2022]) defined an initial set of Rubin-Euclid Derived Data Products (DDPs) specifically to realize the far greater science return of the two surveys combined, with an obvious near-term extension to Roman.
Yet different data access policies across these surveys are hampering efforts to realize those DDPs, blocking the combined analysis the DDP program was designed to enable. The white paper’s recommendation REC-13-SO addresses this directly: it calls for openly sharing EDF-S pixel data to enable DDP development, on the basis that long-term DDP production benefits from an openly shared photometric dataset over a small sky area. Together with the already-public Euclid and future Roman data, this would provide a small, fully open cross-survey dataset for building and validating the pipelines and analyses that full-scale cross-survey science will require. Applications include weak-lensing cosmology, photometry and redshifts for crowded or faint galaxies, AGN and black-hole studies, and cross-matched transient classification.
There is also a strong benefit for AI research. Open datasets have driven some of the most productive advances in AI: the Multimodal Universe dataset, ImageNet, and AlphaFold’s structural archive were all released openly from the start, and each catalyzed a research community that built on it for years afterward. A fully public EDF-S would be precisely the kind of open, scientific dataset that programs such as NSF’s AI-Ready Datasets solicitation (NSF 26-512) are designed to advance: rich enough for AI-driven discovery, and open enough for the community to build the enhancement pipelines and cross-survey harmonization tools that such discovery requires.
EDF-S, rather than COSMOS, is proposed for public release because Euclid does not plan to observe COSMOS as one of its primary dedicated deep fields ([European Space Agency, 2024]). Open, non-proprietary fields have historically become the community’s most productive resources: the COSMOS field remains a cornerstone of astrophysics decades after its inception, precisely because it was kept open from the start. But with nearly twenty years of deep imaging from HST, Spitzer, Chandra, and the VLA, its remaining discovery potential is limited, and for this reason, Euclid has not chosen it as a deep field. EDF-S is a new field observed by Rubin, Euclid and Roman and has decades of discovery potential ahead of it. A fully open Rubin EDF-S has the potential to do for the next generation what COSMOS did for this one.
References
European Space Agency. The euclid deep fields. 2024. URL: https://sci.esa.int/web/euclid/-/61408-the-euclid-deep-fields (visited on 2026-09-18).
Leanne P. Guy, Jean-Charles Cuillandre, Etienne Bachelet, and others. Rubin-Euclid Derived Data Products: Initial Recommendations. In Zenodo id. 5836022, volume 58, 5836022. Zenodo, January 2022. arXiv:2201.03862, doi:10.48550/arXiv.2201.03862.