JWST Proposal Selection Procedures

JWST proposals will be reviewed by panels of scientists from the international astronomical and planetary science communities that will make recommendations to the STScI Director, using well-defined Selection Criteria.

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How STScI Conducts the Proposal Review

JWST programs are selected through competitive peer review. A broad range of scientists from the international astronomical and planetary science community evaluate and rank all submitted proposals using a well-defined set of criteria and paying special attention to any potential conflicts of interest. The review panels and the Executive Committee constitute the Telescope Allocation Committee (TAC) that recommends the science program to the STScI Director. The STScI Director is the Selecting Official for JWST. Based on the recommendations, the Director will make the final allocation of observing time. Full details on the peer review process are given in the JWST Peer Review Guide - Cycle 3



The Review Panels

Dependent on their size, proposals in JWST Cycle 4 will be reviewed either by external panels or by discussion-based review panels.

Discussion panels

The Cycle 4 discussion-based (i.e., face-to-face) review is planned to comprise eighteen topical panels:

  • one Solar System;
  • three Exoplanet Atmospheres and Habitability;
  • two Exoplanetary System Formation and Dynamics;
  • two Stars and Stellar Populations;
  • two Gas, Dust and the ISM;
  • three Nearby Galaxies to Cosmic Noon;
  • three High-Redshift Galaxies and the Distant Universe;
  • two Super Massive Black Holes and Active Galaxies.

The science topics covered by each panel are listed in the definitions of the Scientific Categories in JWST Filling Out the APT Proposal Form. A high-level description of topical coverage in each panel is given in the following table:

Science Category

Topical coverage

Solar System

Proposals to observe or analyse data relevant to objects within the Solar System

Exoplanet Atmospheres and Habitability

Proposals related to investigating the atmospheric properties and/or chemical composition of exoplanets or related objects, through direct or indirect observations or data analysis, or theoretical analysis

Exoplanetary System Formation and Dynamics

Proposals related to planet formation, including investigations of the structure and chemical composition of protoplanetary disks, and dynamical models or simulations

Stars and Stellar Populations

Proposals studying the physics of individual star and star clusters in the Milky Way and nearby galaxies, and investigating the global properties of the resolved stellar populations in nearby galaxies

Gas, Dust and ISM

Proposals studying gas, dust and the interstellar medium in nearby galaxies, including the chemical composition and interactions with winds and shocks

Nearby Galaxies to Cosmic Noon

Proposals investigating galaxy formation and evolution, galaxy clusters and groups, and the galaxy distribution at lower redshifts, extending to the properties of systems at cosmic noon, z~2-3

High-Redshift Galaxies and the Distant Universe

Proposals investigating galaxy formation and evolution, galaxy clusters and groups, and large-scale structure at high redshifts, from z > 3 through z~12 or more

Super Massive Black Holes and Active Galaxies

Proposals studying active galactic nuclei, QSOs, Seyfert galaxies, super-massive black holes and feedback mechanisms

Proposals are assigned to individual reviewers based on the reviewers' expertise and based partly on the keywords given in the proposal and partly on analysis of the proposal text. 

Each panel will be managed by a panel chair, and there will be two TAC chairs overseeing the review process, one for the Galactic panels and one for the Extragalactic panels. Panelists are chosen based on their expertise in one or more of the areas under review by the panels. The face-to-face Discussion Panels assess and grade Small (> 20 and ≤ 50 hours), Medium (> 50 and ≤ 130 hours) and all Target of Opportunity and Survey proposals, regardless of size.  The time allocated to each panel is proportional to the time requested by the proposals assigned to that panel; there are separate allocations for Small and Medium proposals. Discussion Panels do not adjudicate Large (>130 hours) or Treasury GO proposals or AR Legacy proposals, but they will advise their chair on the scientific merit of the subset of those proposals assigned to their panel.

External panels

The Very Small GO proposals (≤ 20 hours) and regular AR proposals will be distributed for external review. Those proposals will be assessed by five experts who will grade on an absolute scale against the primary criteria, as discussed below. External Panels are chosen based on their expertise in one or more of the scientific topics covered by the panel. Each external panelist will receive a limited number of proposals. The proposals will be grouped by subject area; the proposals likely to be recommended to the Director for acceptance will be provided to the Panel Chairs of the face-to-face Discussion Panels of that same Scientific Category prior to the meeting to allow them to identify potential duplications with the proposals reviewed by their panels. 

The review panels will follow dual anonymous protocols, with the exception of a team expertise review for the highest-ranked proposals after ranking has been completed. It is important that submissions conform to the requirements of this type of review. Failure to do so will result in the disqualification of the submission. See JWST Anonymous Proposal Reviews for more information on what is required for the Cycle 4 review.


The Executive Committee

Based on recommendations by the Cycle 3 Executive Committee (EC) to reduce workload and to better match reviewers' expertise,  the Cycle 4 EC review will be split into two parts: Galactic EC and Extragalactic EC.  Discussion panels will have Vice Chairs that do not review Discussion proposals. Instead, they participate as panelists in the EC and they help the Panel Chair with Panel Chair duties. Vice Chairs will help alleviate proposal conflicts for the Panel Chair. Each of the two Executive Committees will include a TAC Chair, the Chairs and Vice Chairs from all the corresponding panels, and, typically, three at-large members chosen to provide broad expertise across a wide range of scientific categories. The primary responsibility of the ECs is to review Large GO proposals (> 130 hours), Treasury GO programs, Legacy AR programs and other requests for substantial resources, such as large Pure Parallel programs. The ECs are provided additional input on proposals through reviews written by external Expert Reviewers and feedback from the discussion panels via the panel chair.  



The Expert Reviewers

Expert reviewers provide asynchronous reviews for: (1) proposals evaluated by the Executive Committees; (2) proposals with a large number of panelists that are conflicted; (3) joint-observatory proposals. In the latter case, the Expert Reviewers are drawn from the joint-observatories' user communities. 



Selection Criteria

Primary Criteria for All Proposals

Evaluations of JWST proposals are based on the following three primary criteria. Each criterion is given a separate grade, then the grades are combined with equal weight. Reviewers will be instructed to evaluate these criteria based on what is written in the proposal.

(A) In-field Impact:

  • The scientific merit of the program within its immediate sub-field, and its contribution to advancement of knowledge.
  • The immediate sub-field of the proposal is the niche area of the program, not the whole broad science area (e.g. Trans-Neptunian Objects, not Solar System Astronomy).
  • Proposals should address how the proposed program will improve understanding of the objects, classes of object, or specialist topics under study, and why the work is relevant and timely.

(B) Out-of-field Impact:

  • The program’s impact outside of its immediate sub-field.
  • A proposal does not have to impact all of astronomy. The out-of-field impacts could be in other sub-fields within the broader science area of the proposal, or in other broad science areas (e.g. in the case of a TNO proposal, this could be solar system formation or planet formation in general, among others).
  • Proposals should discuss implications for other fields or sub-fields, and their breadth, significance, and timeliness.

(C) Suitability & Feasibility:

  • The suitability of JWST observations or datasets, or relevance to JWST science. The necessity of special requirements. The feasibility of the science program.
  • Proposals should demonstrate that the capabilities of JWST are required to achieve the scientific goals, or demonstrate the relevance of the work to JWST science. Technical issues will be adjudicated by STScI instrument scientists.
  • Proposals should include a clear observing or analysis plan that demonstrates a clear path to science. Proposals should justify time requests and any special requirements, including duplications or joint observatory time.

Further information on the grading rubric, including example cases, are included in the Selection Criteria and Scoring System - Cycle 3 guide. 

Additional criteria exist as well, depending on the Proposal Category, as listed below. Letters in square brackets indicate the affected Primary Criteria.

Additional Criteria for All GO Proposals

  • The rationale for selecting the type and number of targets: Reviewers will be instructed to recommend or reject proposals as they are and to refrain from object or hour trimming. Therefore, it is very important to strongly justify both the selection and the number of targets in your proposal, as well as the number of hours requested. [C]
  • The reasonability of requested resources. [C] 

Additional Criteria for Large GO, Treasury GO, and Legacy AR proposals

  • The level of coordination of the overall work described and the production of appropriate databases and/or tools. [C]
  • The utility of the higher-level data products and/or tools. [A,B]

Additional Criteria for Treasury GO proposals and Legacy AR Proposals

  • The extent to which the data products will enable additional scientific investigations and the importance of those investigations.[A,B]
  • The level of data products produced and plans for their timely dissemination to the community. High-level science products should be made available through the MAST data archive or related channels. [C]

Additional Criteria for Survey Proposals

  • The TAC will evaluate the science within the context of the optimal number of targets and minimum number of targets indicated in the Special Requirements Section of the proposal. [C]

Additional Criterion for Calibration Proposals

  • The extent to which these observations or analyses enable new types of scientific investigations with JWST and the importance of those observations. [A,B]

Additional Criteria for all Archival Proposals

  • The improvement or addition of scientific knowledge with respect to the original use of the data. In particular, a strong justification must be given to reanalyze data if the new project has the same science goals as the original proposal. [A,B]
  • A well-developed analysis plan describing how the scientific objectives will be realized. [C]

Additional Criteria for Theory Proposals

  • The extent and importance of JWST science investigations enabled by the theoretical analysis and results. [A,B,C] 
  • The level of planning for timely dissemination of theoretical results, and possibly software or tools, to the community. [C]

Additional Criteria for Community Data Science Software Proposals

  • The relevance of the proposed software development to JWST science investigations and/or data reduction or interpretation. [A,B,C]
  • The level of planning for timely dissemination of the proposed software products to the community. [C]


Next: JWST Guidelines and Checklist for Proposal Preparation




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