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STScI Newsletter
2023 / Volume 40 / Issue 01

About this Article

K. Gilbert (kgilbert[at]

The Roman field of view is overlaid with a Sky Survey that features many galaxies. Some of the various types of galaxies are called out as an example of what Roman will see.
Figure 1: The primary goal of the community-led process to define Roman’s Core Community Surveys is to maximize the scientific yield of these wide field infrared surveys.  For example, the High Latitude Wide Area Survey will provide near infrared observations of hundreds of millions of galaxies at Hubble-like resolution and sensitivity.  The choice of filters, trades between area and depth, survey location, and other observational strategy choices will determine the science that can be achieved with this survey.  By responding to the current request for community input, you will help ensure that Roman’s Core Community Surveys meet the needs and expectations of the community.

Background Image: Digitized Sky Survey

Galaxy Images:  NASAESA, M. Sun (University of Alabama), W. Cramer and J. Kenney (Yale University), J. Mack (STScI), and J. Madrid (Australian Telescope National Facility) and Hubble Heritage Team (STScI/AURA).

Image Composition:  A. Pagan (STScI)

The Nancy Grace Roman Space Telescope’s Wide Field Instrument (WFI) will have a large field of view (0.28 sq deg), Hubble-like sensitivity and resolution, and highly efficient survey operations, enabling survey speeds roughly 1000 times faster than achieved with Hubble (Akeson et al. 2019). The first five years of the Roman Space Telescope’s observing program will be a mix of large, community defined surveys (the Core Community Surveys) with the WFI; competitively selected, principal investigator-led General Astrophysics Surveys with the WFI, nominally comprising at least 25% of Roman’s observing time; and a technology demonstration program with the Coronagraphic Instrument. Since all Roman data will be publicly available immediately, a large fraction of Roman users are anticipated to interact primarily, or exclusively, with Roman’s data archive.

Roman’s Core Community Surveys (CCSs) will be defined by the astronomical community and will include a High Latitude Wide Area survey, a High Latitude Time Domain survey, and a Galactic Bulge Time Domain survey. The CCSs, which combined are anticipated to use the majority of Roman’s observing time during the first five years, will enable a broad range of astrophysical investigations while meeting the Roman Space Telescope’s scientific mission requirements in cosmology and exoplanet demographics.    

The planning and preparation to enable and maximize the rich scientific return of Roman’s observing program has already begun, and will continue up until, and after, Roman’s launch, planned for late 2026. A number of diverse opportunities are, and will be, available to the community to engage with the Roman Mission, both in preparatory activities before launch and during operations.  These include:

  • Participating as individuals in the definition of the CCSs, via responding to requests for information from the Roman Mission, participating in workshops, or serving on or supporting the work of the community-led committees to be charged with defining the CCSs.
  • Engaging deeply with specific topics via ongoing technical working groups.
  • Applying for funding for preparatory activities before launch through NASA/ROSES opportunities. 
  • Participating in Roman Science Collaborations, which will be formed to grow community networks, explore Roman’s capabilities in different science areas, and prepare for analysis of Roman’s large datasets.
  • Applying for principal investigator-led observing programs or funding to analyze Roman datasets via regular calls for General Investigator proposals during Roman’s operations.  The first call is anticipated to be 1 year prior to launch.
This graph shows when the engagement with the community will occur for definitions, engagement, funding, collaborations, and proposals.
Figure 2: Anticipated timelines for the major ways in which community members can engage with the Roman Mission, up to and through its first five years of operations.

Community-led Definition of the Core Community Surveys

Roman’s primary science objective is performing astrophysics with wide area near-infrared surveys. The cosmology and exoplanet science requirements for the CCSs leave significant parameter space available to define the observational strategies (filters, depth, cadence, etc.) in a way that will enable a broad range of other astrophysical investigations. As one concrete example, in order to meet Roman's dark energy goals, a requirement on the design of the imaging component of the High Latitude Wide Area Survey is to enable precision measurements of the shapes of hundreds of millions of galaxies. This leaves open significant parameter space for the survey data to be relevant for other science areas.

Depending on the choice of filters, the data may be more (or less) useful for studies of galaxy evolution. Depending on the chosen balance of area versus depth, there may be more (or less) opportunity for discovering new celestial objects that are rare per unit area. Moreover, all of these choices may affect how useful the survey data are for studies of more nearby objects, such as those belonging to the Milky Way halo or solar system.

There are anticipated to be many such trades related to this survey, as well as to the other Core Community Surveys. The goal of the community-led definition of the Roman CCSs is thus to determine an observational strategy for each that will maximize their scientific impact by enabling a broad range of astrophysical investigations while providing the observations needed to meet Roman’s science requirements in cosmology and exoplanet demographics. 

Initial Community Input

The community-led definition of the CCSs is being initiated with an open call to all astronomical community members to provide information on the science investigations they wish to see enabled by the design of the CCSs. The purpose of the call is to solicit from the community descriptions of specific scientific investigations that can be achieved with the CCSs, the observational strategies that will enable these investigations to be performed with a given CCS, and the metrics or figures of merit that can be used to assess whether an observational strategy will enable a particular investigation. 

The Roman Mission is offering two avenues for members of the community to provide information on science drivers and the requirements they place on the design of the Core Community Surveys: a short, one to two paragraph 'science pitch' (including a questionnaire), due by February 17, 2023, and/or submission of a technically focused white paper, anticipated to be due in late spring, 2023. The full text of the call provides additional context on how the responses will be used. 

The CCS Definition Committees

The Roman Mission will use the results of the initial community input to form committees for each CCS composed of members of the astronomical community who represent the breadth of science the community wants to see enabled with each CCS. These committees will be formed in mid-2023 and will be charged with defining the CCS observational strategies in a way that maximizes the science that can be achieved with each survey, and represents the interests of the full astronomical community. 

The CCS definition committees will use the initial community input to begin the work of determining the optimal survey definitions, including identifying where additional investigative work and community input or consensus building is needed. The CCS definition committees, with the support of the Roman Science Centers at STScI and IPAC, will continue to engage with the astronomical community as they consider observational strategy trades and their impacts on science investigations while iteratively developing the survey concepts.

Determining the Final Definition of Roman’s CCSs

Each of the CCS definition committees will be charged with providing several survey options, and an analysis of the impact on various science investigations for each option. These will be provided to a Roman Observations Time Allocation Committee, also composed of community members representing the full breadth of science investigations, which will be charged with making a final recommendation to the Roman Mission on the balance between each of the CCSs, as well as between the CCSs and the general astrophysics survey allocation. The CCS definition committees will then be tasked with providing the Roman Science Centers with survey definitions that are sufficiently detailed that the Science Centers can schedule the observations. 

Additional reviews of the CCSs by community-led committees will be planned prior to launch and approximately one year into observations, in order to take into account new information on observatory performance.

This graph shows the timeline for developing Roman’s surveys
Figure 3: Timeline for definition of Roman’s CCSs. Key activities include (1) the initial request for community input; (2) formation of the CCS definition committees; (3) committee-driven investigations, gathering of additional community input, including via community workshops, and committee deliberations, culminating in a recommendation to the Roman Project on the balance between the three CCSs; and (4) the final report detailing CCS observations, due to the Roman Project 18 months before launch.
The Roman Time Allocation Committee will look at the three core committees.
Figure 4: The three definition committees, one for each CCS, will be charged with understanding and representing the full breadth of the astronomy community’s interests in Roman’s CCSs.  They will solicit and evaluate community input, evaluate survey options against science metrics, and produce recommendations for survey implementations with options for enhancements/descopes to the Roman Observations Time Allocation Committee (ROSTAC).  The ROSTAC will evaluate the recommendations of the CCS definition committees and provide recommendations to the Roman Project on the balance between each of the core community surveys.

Engaging with Project Partners on Specific Technical Topics

 The Roman Mission convenes a number of Roman Technical Working Groups. These working groups provide a forum for the Roman Project, the Roman Science Centers, and the science community to work together on topics that cut across science areas.  The focus, membership, and activity of these working groups change over time, according to Roman’s development needs.  Examples include groups focused on calibration, astrometry, software development, simulations, detectors, and spectroscopy.  Find information on currently active working groups and instructions on joining, including expectations for those who join.

Funded Preparatory Science Activities

Members of the science community at US institutions can apply for support to participate in Roman preparatory science activities via the Roman elements of ROSES solicitations.  

A previous ROSES solicitation in 2015 funded Science Investigation Teams that provided input to the Roman Mission through 2021. A workshop was held in November 2021 presenting the outcomes of the Science Investigation Teams’ activities; both videos of the presentations and copies of the presentation slides are available.

The current Roman ROSES solicitation, due March 21, 2023, provides opportunities for US scientists to apply for funded participation in the development of the Roman Project in one of three ways.  A broad range of science preparation activities can be funded through Wide Field Science investigations.  Significant and sustained funding to develop the scientific infrastructure needed for the community to achieve Roman’s science goals can be obtained through selection as a Project Infrastructure Team.  Selections for membership in the Coronagraph Community Participation Program (CPP) Team will provide the opportunity to work collaboratively with the Roman Coronagraph Instrument team and the IPAC Science Support Center to prepare for the in-space technology demonstration. Documentation and other resources are available to support ROSES proposals. 

A second Roman ROSES solicitation for preparatory science activities is anticipated to be offered approximately two years before Roman’s launch. 

Joining Roman Science Collaborations

The formation of community-led Science Collaborations will be facilitated by the Roman Mission. The goal of the science collaborations will be to enable people to engage with Roman science independently of NASA-led, peer-reviewed selections for funding or observing programs, for example in preparing to analyze data on the scale of Roman surveys for specific science investigations.  Collaboration areas may include topics such as time domain science, nearby galaxies, and galaxy evolution, well as dark energy and exoplanets.

The Roman Mission will work with the community to shape the definition and charter of the collaborations. The formation of the Roman Science Collaborations is anticipated to begin in mid-2023, after the selection of funded teams and individual investigators from the 2022 Roman ROSES call. The Science Collaborations will be open to, and are expected to be driven and organized by, all interested community members, following the successful model of the Rubin science collaborations. They will support their members and the broader astronomy community in preparing to most effectively utilize Roman’s unique observational capabilities and analyze Roman’s large survey datasets.

General Investigator Opportunities Before and After Launch

As Roman approaches launch and enters operations, there will be regular calls for Principal Investigator-led Roman General Astrophysics Surveys, as well as for funded archival programs.  Funded General Investigator programs will use the wealth of data in Roman’s archive to perform all manner of astrophysical investigations, including but not limited to addressing Roman’s cosmology and exoplanet demographic science goals. The selection of these programs will be made via a peer review process. The first of these calls is anticipated to be made approximately one year before Roman’s launch, after the definition of the CCSs is complete.

The Roman Field of View overlaid the Hubble mosaic of the Carina Nebula showing a callout of the star forming regions.
Figure 5: Roman’s wide field of view, Hubble-like sensitivity and resolution, and fast slew and settle times will enable a broad range of astrophysical investigations beyond what can be accomplished with the CCSs. This example highlights the breadth of environments within a Galactic star forming region observed with a single Roman WFI footprint. Opportunities to propose principal investigator-led astrophysics surveys will be available at a regular cadence starting approximately one year before launch.

Background image: N. Smith, University of Minnesota/NOIRLab/NOAO/AURA/NSFHubble
Mosaic: Hubble Image: NASAESA, N. Smith (University of California, Berkeley), and The Hubble Heritage Team (STScI/AURA); CTIO Image: N. Smith (University of California, Berkeley) and NOAO/AURA/NSF
Mystic Mt.: NASAESA, and M. Livio and the Hubble 20th Anniversary Team (STScI)
Eta Carina: NASAESA, N. Smith (University of Arizona), and J. Morse (BoldlyGo Institute)
Trumpler 14: NASAESA, and J. Maíz Apellániz (Institute of Astrophysics of Andalusia, Spain)

Acknowledgment: N. Smith (University of Arizona)

Composition:  A. Pagan (STScI)

Keeping Up to Date with Roman

The above summarizes the major ways in which community members can engage with the Roman Mission, both now and in the future. Additional details can be found on the Roman website at GSFC.  In addition, there is an on-going series of conferences focused on science topics relevant to Roman’s unique capabilities. The next conference in the series, “Roman Science Inspired by Emerging JWST Results,” will be held at STScI, June 20-23, with both in-person and remote participation options.

Community members can stay up to date with Roman by attending the monthly “Roman Community Forum,” held nominally on the fourth Wednesday of each month, and by signing up to receive regular updates from the Roman Project at GSFC1, from the Roman Science Operations Center at STScI2, and from the Roman Science Support Center at IPAC3. Community members are also encouraged to engage with their representatives on standing Roman advisory committees.  These include the Roman Science Interest Group (RSIG), which advises the Roman Project Science Office at GSFC, and the Roman Space Telescope Advisory Committee (RSTAC), which advises the STScI Director.


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