Roman Community-defined Surveys
Welcome to the Roman Documentation (RDox) home for the Roman Community-defined Surveys!
The Roman mission will include programs under two main categories: Core Community Surveys (CCS) and General Astrophysics Surveys (GAS). While both provide broad opportunities for astrophysical research, they differ in scope and purpose:
Core Community Surveys (CCS) are designed to address the foundational questions that define the mission’s science requirements, including probing dark energy, dark matter, and the demographics of cold exoplanets. These surveys are community-defined. They were developed through an open, collaborative process that engaged the broader scientific community to ensure the surveys enable a wide range of investigations beyond the core mission goals. CCS programs are allocated approximately 75% of the science operations time during the nominal five-year mission. Users are strongly encouraged to leverage these rich datasets for their science goals.
General Astrophysics Surveys (GAS) programs may address any area of astrophysics. GAS programs may be community-defined or PI-led, with PI-led programs solicited through open Calls for Proposals and awarded via a competitive time allocation process.
Importantly, all Roman survey data, both CCS and GAS, will be publicly available with no proprietary period. This commitment is aimed at maximizing scientific return and fostering broad participation in Roman science.
No Proprietary Data
All Roman data will be publicly available with no proprietary period for both CCS and GAS.
This page provides an overview of the existing community-defined surveys and offers resources to explore survey details, including expected depth and data quality. Additionally, the related articles linked below describe each survey's scientific goals and observational implementation in greater detail:
Defining Roman's Community Surveys
Community-defined surveys are a cornerstone of the Roman mission and were developed through extensive engagement with the scientific community. This process included white papers, science pitches, community forums, and Definition Committees composed of subject-matter experts. The collaborative approach ensures that no single individual or collaboration owns a survey, and that the resulting programs serve the broadest possible range of scientific investigations.
These surveys include the Core Community Surveys (CCS), designed to meet Roman’s science requirements while enabling broad astrophysical research, and General Astrophysics Surveys (GAS), which will enable science investigations beyond those that can be accomplished with the CCS. CCS programs represent the majority of Roman’s observing time during the nominal five-year mission. At present, three CCS surveys and one GAS survey have been defined by the community.
The Definition Committees produced detailed reports outlining their recommended survey designs and the science they enable. These reports were reviewed by the Roman Observations Time Allocation Committee (ROTAC), which made implementation recommendations to the Roman Mission, considering impacts on other community-defined surveys and GAS programs. A summary of the work by the Definition Committees and ROTAC, including committee membership and a timeline for the core community surveys, is available on the GSFC website. The ROTAC Report, which includes each Definition Committee report in its appendix, can be found on ADS and arXiv.
The four community-defined surveys are introduced in the sections below, and their footprints are displayed in the Roman Surveys All-Sky Overview Figure.
Roman Community-defined Surveys: All-Sky Overview Figure
A sky map showing the four community-defined surveys. The HLWAS regions appear in three shades of blue, with the darkest indicating the deep fields. Red circles mark the North and South fields of the HLTDS. The proposed GPS footprint is outlined in yellow, and within it, a small inset highlights the GBTDS footprint in orange.
High-Latitude Time-Domain Survey
The High-Latitude Time-Domain Survey (HLTDS) will achieve the Roman mission’s objective of probing dark energy by detecting and using Type Ia supernovae (SNe Ia) to trace the universe’s expansion history. In addition, the survey will identify and characterize a wide range of time-variable astrophysical sources in the near-infrared. Both the northern and southern fields will be observed on an approximately five-day cadence during the mission’s central two years, producing an expected sample of about 100,000 transient light curves.
Please click here for more information about the High-Latitude Time-Domain Survey.
High-Latitude Wide-Area Survey
The High-Latitude Wide-Area Survey (HLWAS) will fulfill the Roman mission’s objectives to investigate the nature of dark energy and dark matter through large-scale measurements of weak gravitational lensing and galaxy clustering. In addition to these core goals, the survey will enable a broad range of astrophysical investigations. The HLWAS consists of multiple tiers with varying exposure depths and will cover more than 12% of the sky.
Please click here for more information about the High-Latitude Wide-Area survey.
Galactic Bulge Time-Domain Survey
The Galactic Bulge Time-Domain Survey (GBTDS) will fulfill the Roman mission’s objective to determine the distribution and properties of exoplanets in the Milky Way by enabling microlensing detections of small, cold exoplanets. In addition, the survey will provide high-cadence observations that support a wide range of investigations into stellar and Galactic physics. The GBTDS is expected to discover on the order of 100,000 exoplanets through a combination of microlensing and transit detections.
Please click here for more information about the Galactic-Bulge Time-Domain Survey.
Galactic Plane Survey
The Galactic Plane Survey (GPS) will observe a significant fraction of stars in the Milky Way, with an estimated total of about 20 billion sources. The survey will combine wide-field imaging, time-domain observations, and spectroscopy to study stellar populations, Galactic structure, and regions of high extinction across the bulge and disk.
Please click here for more information about the Galactic Plane Survey.
Additional Resources for Community-defined Surveys
The Table of Resources for Community-defined Surveys below summarizes additional documentation and resources that provide further details and support for the community-defined surveys described above. For materials available through the Roman Research Nexus, please visit the Nexus article to learn more about using the platform. Additional resources will be added as they become available.
Table of Resources for Community-defined Surveys
| Resource | Description | Where to find more information |
|---|---|---|
| ROTAC and Definition Committee Reports | Detailed descriptions of survey designs, science goals, and the rationale for specific components and trade-offs. There is one report for the ROTAC and one for each Definition Committee. |
|
| APT Demonstration Programs | Example Observation Specifications for the community-defined surveys. | Access via APT menu (File → Demonstration Programs) or by using IDs: 966 (GPS), 967 (GBTDS), 968 (HLTDS), 969 (HLWAS). More details are in the Astronomers Proposal Tool (APT) article. |
| Exposure Time Calculator Workbooks | Sample workbooks in the Exposure Time Calculator (ETC) matching community-defined survey Observation Specifications. | Available through the Roman WFI ETC Web Interface by clicking “Sample Workbooks” on the Available Workbooks page. |
| Simulated Datasets | Generated using observation specifications of the Core Community Surveys with Roman I-Sim, incorporating both astronomical objects and instrumental signatures. | Will be available on the Roman Research Nexus (RRN) by the end of 2025. |
| Roman Data | The Data Handbook provides guidance on data processing and its impact on observation design. | See the WFI Data Levels and Products article for an overview. |
For additional questions not answered in this article, please contact the Roman Help Desk.
References
- Core Community Surveys: Overviews and Definition, NASA/GSFC, accessed 22 August 2025.
- "Roman Observations Time Allocation Committee: Final Report and Recommendations", Roman Observations Time Allocation Committee and Core Community Survey Definition Committees, arXiv:2505.10574, 2025. doi:10.48550/arXiv.2505.10574.