JWST New and Important Features

New and important features for proposers to consider in Cycle 5 are covered in this article.

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What's new for Cycle 5

Recent updates

Capabilities offered

  • The full suite of JWST capabilities is offered in the Cycle 5 Call for Proposals, including new capabilities not previously available. Proposers should write proposals assuming all capabilities will be available. All proposals will be scientifically evaluated by the Telescope Allocation Committee (TAC). However, given the uncertainties in NASA funding levels at the time of this call, the capabilities ultimately available during the observing cycle may be different than those offered at this time. STScI is unable to provide further guidance at present and will keep the JWST community informed of such developments as soon as feasible via the JWST Observer News and Late Breaking News. 

Observing time

  • JWST will be offering 8,000 hours for observations in Cycle 5 as compared with 8,500 hours in Cycle 4. The transition from Cycle 3 to Cycle 4 warranted a significant increase in the pool of available observing time (5,500 to 8,500 hours), given the cessation of GTO and ERS programs, well-established observatory efficiency, and the need for a sufficient program pool to maintain that scheduling efficiency. The Cycle 5 pool will be slightly reduced, to 8,000 hours, to continue tuning the program pool to maintain scheduling efficiency while completing programs in a timely manner. 
  • Based on the Cycle 4 proportional allocation, we anticipate that the distribution of hours among proposal size categories will be approximately:
    • 1,300 hours for Very Small; 
    • 2,800 hours for Small;
    • 2,500 hours for Medium; and
    • 1,400 hours for Large and Treasury programs.

The exact allocations will depend upon the Cycle 5 proposal pressure.

  • We anticipate that up to 1,000 Survey targets may be planned for Cycle 5. 

Special initiatives

  • STScI is introducing a new initiative for Long-Term Monitoring programs. These programs should aim to exploit the expectation for a 20-year lifetime for JWST and/or HST's 30-plus year heritage of observations. For more information, see JWST Special Initiatives.
  • STScI is introducing a new initiative for Roman Preparatory Science programs. This initiative is designed to encourage observations with JWST that complement and enhance the scientific impact of Roman Space Telescope observations, or that are essential to achieving critical science goals of future Roman programs. For more information, see JWST Special Initiatives.

New instrument modes

  • Several new instrument modes are being offered this cycle. Details can be found in the Instrument updates section on this page.

New Joint JWST-TESS Observing Proposals

Increased number of keywords in APT

  • To facilitate the proposal review process, the required number of keywords to be entered into APT has increased. The new minimum number of keywords is three (3), and the maximum number is ten (10). For more information, please see the Scientific Category section of JWST Filling Out the APT Proposal Form.
  • Additionally, new keywords have been added to several science categories. Proposers are encouraged to review the keywords in their science area by visiting the Appendix - Science Keywords.

Important updates and reminders

The following are important features that proposers should keep in mind when crafting their proposals.

Policy

  • The APT Template and Special Requirements
    Program Change Requests to the Telescope Time Review Board (TTRB) are straining scheduling and program reviews by the instrument teams and the Program Coordinators. Moving forward, the TTRB will become more strict in its approvals of change requests derived from proposals lacking the appropriate observation specifications and special requirements. Proposers are required to include all relevant observation specifications, including any special requirements for each observation, in both the APT submission and the PDF attachment. Proposers must fill the APT Proposal Information form appropriately using the checkboxes and the expandable menus. If these fields are not marked and filled out in APT, those requests may not be met, even if they are described in the proposal. For more information, see JWST Filling Out the APT Proposal Form. JWST Observation Planning Essentials summarizes the items that must be complete at the proposal stage. 

  • Page limits & formatting:
    Proposers should check the page limits carefully. Proposals that exceed the page limits will be subject to disqualification. For more information see JWST Preparation of the PDF Attachment.

Proposers should not change the format of any templates provided by STScI, including but not limited to changing the font size, figure caption size, margins, line spacing, and kerning. Proposals that change the formatting will be subject to disqualification. Changing the font style is strongly discouraged and may result in disqualification.

  • Science categories:

The Science Categories were adjusted in Cycle 4 to better match JWST science topic distributions and continue for Cycle 5. For more information, see the descriptions in JWST Proposal Selection Procedures and JWST Filling Out the APT Proposal Form.

  • Coordinated parallel observations:

Coordinated parallel observations are possible with many prime modes. In past cycles, the science goals for the parallels were required to align closely with the prime science program; starting this cycle, coordinated observations may be proposed to advance goals that complement or enhance the prime science. The scientific justification for the coordinated observations should be described in the “Justify Coordinated Parallel Observations” section of the PDF Attachment.

  • Use of Generative Artificial Intelligence (GAI) technology:

    Proposers are not prohibited from the use of Generative Artificial Intelligence (GAI) tools, such as ChatGPT. However, following NASA policy, the proposal must acknowledge content that is not the creative product of the proposal team. Thus, any material contained in the proposal that is derived from GAI must be described and cited, e.g., the name of the program, version number, the date and time, and a short statement on how the GAI was used. This information must be included with the References and does not count against the page limits. Failure to disclose the use of GAI will result in disqualification. For further information, see the full Policy on the use of GAI tools.

  • Multiple in-cycle submissions:

Before the proposals are distributed to the reviewers, STScI checks all submitted proposals for multiple in-cycle submissions across scientific categories and across size categories. By multiple in-cycle submissions we refer to proposals with the same or nearly the same team, science goals, and targets. STScI reserves the right to reject all such proposals as non-compliant in the case of egregious violations, as they negatively impact the fairness of the selection process and result in unnecessary burden for the reviewers. Please see JWST Proposal Submission Policies for more information.

Proposal review

  • Proposal classes and size boundaries:

The GO proposal sizes boundaries were changed in Cycle 4 and continue for Cycle 5. Different proposal classes and sizes are reviewed by different subsets of reviewers as described in JWST Proposal Selection Procedures. Proposers should note the breadth of expertise in each panel and write for the appropriate audience.

  • Two Executive Committees - Galactic & Extragalactic:

As introduced in Cycle 4, the Cycle 5 Executive Committee (EC) review will be split into two parts: Galactic EC and Extragalactic EC. Further details on this division are given in JWST Proposal Selection Procedures. Proposers should note the breadth of expertise on each EC and write for the appropriate audience.

  • Re-use of published text and dual anonymous review:

Proposals may not include substantial verbatim extracts from previously-published materials, including white papers or accepted proposals. Such inclusions are contrary to dual anonymous review since the re-use of material implicitly identifies the authors of the proposal. Proposals violating this requirement are subject to disqualification. Further details are given in the Compliance section of the JWST Anonymous Proposal Review guidance. 

APT updates

  • APT version:

Cycle 5 proposers should use the Astronomer's Proposal Tool (APT) version 2025.5 or higher for proposal preparation, released on August 22, 2025. Details can be found in the release notes (for current and past versions). Proposers can generate programs in APT using previous versions but would need to update to version 2025.5 or higher before final submission. 

  • Keywords:

The number of keywords required in APT has increased to a minimum of 3 and a maximum of 10, as described under What's New for Cycle 5 above.

  • New instrument modes:

APT supports the new instrument modes being offered this cycle; please see Instrument updates below for details.

  • ETC Workbook Calculation ID:

Proposers are reminded that including a link to ETC Workbook Calculation IDs is optional, not required.

ETC updates

  • ETC version:

Cycle 5 proposers should use the JWST Exposure Time Calculator (ETC) version 5.0, released July 31, 2025.  Updates for version 5.0 include αdded support for MIRI Wide Field Slitless Spectroscopy mode and 4 new NIRISS SOSS multi-stripe subarrays, updated SIAF parameters and calculation defaults, UI improvements for easier sharing and better error messaging, and backend improvements to support hundreds of simultaneous users. See the release notes for details, and be sure to review the known issues for this release. Instructions for downloading the latest version of the ETC's Pandeia engine as a Python module, with the associated data, are found in the Installing Pandeia page and the Pandeia Engine News page.

  • Reduced count rate in MIRI Imaging, Coronagraphic Imaging, and Medium-Resolution Spectroscopy (MRS):

Latest information on the evolution of the MIRI Imager and MRS long wavelength reduced count rates is based on the currently observed trend projected to the end of June 2026. Visit the MIRI MRS Calibration Status page to understand MRS Channel 4C ETC discrepancies with respect to the latest measurements. For the remaining MIRI MRS channels, imaging, and coronagraphy, ETC predictions are consistent with the end of Cycle 5 projected behavior.

JWST Cycle 5 proposers should explicitly state in their proposals if their science critically depends on MIRI MRS Channel 4C, and quantify how the projected count rate evolution will impact future attempts to obtain the science.

  • Improved user load handling:

In the days before the JWST Cycle 4 proposal deadline, many users experienced extremely slow page loading and unreliable service from the ETC. A variety of backend improvements have been made that aim to prevent a similar occurrence during the high volume of users expected before the Cycle 5 submission deadline. Browser load tests and better distribution of AWS resources for calculations show the ETC can now support upwards of 400 simultaneous users with load times of only a few seconds during peak usage. Proposers should consider working on their ETC calculations early to avoid overwhelming last minute ETC usage.

Instrument updates

(Proposers interested in these new instrument modes should make note of this disclaimer.)

Opportunities

  • Future Cycles GO proposals:

Proposers may request time in up to three cycles (5, 6, and 7), or in up to five cycles under the Long-Term Monitoring Initiative. Future Cycles Proposals should describe in the PDF Attachment the entire requested program and provide a cycle-by-cycle breakdown of the number of hours requested. The cycle-by-cycle breakdown also needs to be entered in the APT Proposal Information form using the "Future Cycles” menu; see JWST Filling Out the APT Proposal Form. If this field is not marked and filled out, the Future Cycles request might not be met, even if it is described in the proposal. The APT file should only contain the observation specifications corresponding to the current cycle. APT files for time awarded in Future Cycles will be requested at a later time. See Future Cycles GO Proposals for more information.

  • Joint JWST Observing programs:

There are Joint JWST Observing program opportunities with ALMA, Chandra, HST, NASA Keck, NOIRLab, NRAO, TESS, and/or XMM-Newton. Joint JWST programs with more than one observatory are allowed. Joint proposals aim to remove double jeopardy. They should be submitted only once to the facility that represents the prime science, not to both observatories. Proposers are responsible for fulfilling all necessary requirements requested by the partner observatories. This includes noting what information needs to be submitted, meeting the deadlines for submitting that information, and ensuring that contact details are up to date. Proposers may request simultaneous observations with partner observatories, but there is no guarantee that such requests can be executed. Proposers taking advantage of Joint JWST Proposal opportunities should enter their request in the "Coordinated Telescopes" section of the APT Proposal Information form; see JWST Filling Out the APT Proposal Form. Joint JWST observing proposals are available for GO programs only. See Joint Observing Programs for further information.

  • Survey programs:

Survey programs consist of similar, relatively short observations of targets drawn from a large sample; unlike GO programs, they will serve two main purposes in Cycle 5: supplementing the Long Range Plan to maintain observing efficiency if there is a shortfall of GO programs; and providing simple observations that can be executed when data volume is constrained by external factors (for example, during the Artemis mission data downlink capability may be severely limited). Survey programs have no guaranteed completion fraction. Proposals are for a number of targets, not time; proposers must specify the minimum number of targets to achieve the science goals in the Special Requirements section. See Survey Programs for further information. NIRSpec MOS and MIRI MRS are not available for Surveys.  

  • Target of Opportunity (ToO) observations:

Please see the Target of Opportunity (ToO) Observations section of the JWST Observation Types page for details.

Ultra-disruptive and Disruptive ToOs are not permitted with NIRSpec MOS. Pure Parallel Programs may not contain a ToO component.

Standard ToO proposals have a duration of one cycle. Proposers may apply for "carry-over" status if the target phenomena have a low probability of occurrence during one cycle. The proposal needs to include an estimate of the likely probability of occurrence in Cycle 5 (i.e., an annual probability). Carry-over ToOs are allowed for both disruptive and non-disruptive observations.  

As with other GO categories, non-disruptive ToO proposals can request triggers in up to three cycles (5, 6, and 7) as a Future Cycles program, or in up to five cycles under the Long-Term Monitoring Initiative. (Ultra-)Disruptive ToO proposals are restricted to the current cycle. Future Cycle ToOs are not eligible for carry-over status. Requests for carry-over status or future cycle allocations must be justified in the APT Special Requirements and marked on the APT Proposal Information form. 

In the case of duplications, triggers from previous cycle proposals have priority. 

  • Pure Parallel programs:

Pure Parallel programs may propose for observations with NIRCam imaging, NIRCam WFSS, NIRISS imaging, NIRISS WFSS, and MIRI imaging and are subject to other constraints. Please see the Pure Parallels documentation and the JWST Observation Types page for more information.

  • Legacy AR proposals:

Currently, Legacy Archival (AR) Proposals are being offered this cycle. However, proposers interested in submitting Legacy AR Proposals should be mindful of this disclaimer.

  • Rocky Worlds Director’s Discretionary (DD) Time program:

Rocky Worlds is a large-scale DD program to look at rocky exoplanets orbiting nearby M-dwarf stars in secondary eclipse using approximately 500 hours of JWST observations to search for atmospheres and approximately 250 orbits of HST observations to characterize their host stars in the UV. Observations have no exclusive access period, and are immediately available to the community. The community is encouraged to consider submitting Cycle 5 proposals to supplement and complement the Rocky Worlds DD program. This includes Archival proposals to analyze all or a subset of the full Rocky Worlds dataset.

At the time of writing, the Rocky Worlds DD program has in its sample four exoplanets that are expected to be observed with 15 micron MIRI photometry: GJ 3929 b, LTT 1445 A c, LTT 1445 A b and LHS 1140 b. The HST host star observations will use COS and STIS. More targets are expected to be selected, with an announcement of those coming out no later than 6 weeks before the JWST Cycle 5 Proposal deadline (i.e., early September).

For more information and details on observing modes and strategy, please see the official Rocky Worlds website: rockyworlds.stsci.edu.

  • Discovery DD proposals:

Discovery DDs are a new class of DD program suitable for observations of compelling scientific urgency that significantly accelerate scientific discovery. These are a supplement to the traditional Time-Critical DD programs. For more information, see Director's Discretionary Time Submission.

  • NASA High-End Computing (HEC) time:

Successful JWST proposers will be eligible to apply for NASA High-End Computing (HEC) Time. Please indicate whether you intend to apply for HEC time in the text of the "Special Requirements" section of the PDF attachment. More information on NASA HEC Program can be found on https://www.hec.nasa.gov.

  • Citizen science with JWST:

GO and AR proposals may also include a citizen science component in support of the science goals. Funded support for those activities must be compliant with the JWST General Grant Provisions and is limited to no more than 10% of the total budget. NASA document SPD-33 provides guidelines on citizen science projects.

  • Laboratory astrophysics:

Laboratory astrophysics relevant to JWST observations is an acceptable component of a GO proposal. Funded support for those activities must be compliant with the JWST STScI General Grant Provisions (GGP) and is limited to no more than 10% of the total budget. This component must be specified and justified in the original science proposal and may not be added subsequent to acceptance.


Next: JWST Proposal Workflow



Notable updates

Originally published