This page describes new features and important updates for proposers to consider in Cycle 6.

Recent updates

Cycle 6 overview

Capabilities offered

The full suite of JWST capabilities is offered in the Cycle 6 Call for Proposals, including new capabilities not previously available. Proposers should write proposals assuming all capabilities will be tested and available. STScI will keep the JWST community informed of any changes via the JWST Observer News and Late Breaking News. All proposals will be scientifically evaluated by the Telescope Allocation Committee (TAC).

Observing time

JWST will be offering up to 7,700 hours for observations in Cycle 6, as compared with 8,000 hours in Cycle 5. This change will reduce the number of programs executing outside of the nominal cycle and balances the competing factors that drive the size of the program pool in a given cycle. A larger pool of programs gives the operational flexibility to maintain a high scheduling efficiency, while a smaller pool of programs ensures that these programs complete in a timely manner.

Based on the Cycle 5 proportional allocation, we anticipate that the distribution of hours among GO proposal size categories will be approximately:

• 1,000 hours for Very Small; 
• 2,300 hours for Small;
• 3,000 hours for Medium; and
• 1,400 hours for Large and Treasury programs.

The exact allocations will depend upon the Cycle 6 proposal pressure.

We anticipate that up to 1,000 Survey targets may be planned for Cycle 6. 

What's new for Cycle 6

A redesigned Call for Proposals

In an effort to make this documentation easier to navigate and information easier to find, the Call for Proposals has been reorganized for Cycle 6. As such, pages bookmarked in previous cycles may need to be updated. We encourage proposers to explore the new layout and to pass any feedback they have along to the JWST Users Committee (JSTUC) or JWST Help Desk.

The new page structure of the Call for Proposals is given below, along with a high-level description of the information on each page.

Science category and keyword updates

Many science categories have been renamed this cycle:

The scope of these categories has not changed from the past cycle.

Several science categories have updated keywords this cycle. Proposers should consult Appendix A - Science Categories and Keywords for the full up-to-date list of science categories and associated keywords.

Changes to how Small GO proposals are reviewed

Given the number of proposals expected in response to the Cycle 6 Call for Proposals, it was necessary to make changes to the proposal review process to effectively manage the proposal load.

Small GO proposals will now be reviewed by the External panels, except

• those to be evaluated by the Solar System Astronomy panel;
• those to be evaluated by the Interstellar Gas and Dust panel;
• Target of Opportunity (ToO) proposals of any science category; and 
• Treasury proposals of any science category.

Small GO Solar System Astronomy and Interstellar Gas and Dust proposals will be evaluated by the Discussion panels. The handling of ToO and Treasury proposals has not changed from last cycle, but are listed here for completeness. The review of all other proposal types is unchanged from previous cycles.

Please see JWST How Your Proposal is Evaluated for more information.

Cycle 6 proposal PIs may be expected to review proposals in Cycle 7

Due to the increasing number of proposals we expect to receive and the increasing strain on the community to serve as reviewers, Principal Investigators (PIs) of submitted Cycle 6 JWST proposals may be expected to serve as reviewers for proposals submitted in response to the Cycle 7 JWST Call for Proposals, or they must nominate a consenting co-PI or co-I to serve as the reviewer in their stead. More information about any expected review service will be provided at a later date.

Proposal PDF attachment template updates

The PDF attachment templates have been updated for Cycle 6. Proposers must use these updated templates, which can be downloaded on the JWST Preparing the Proposal PDF Attachment page.

Proposers must not make any changes to the provided templates. Violations include, but are not limited to, altering the page size, margins, font size, font style, line spacing, kerning, figure caption font sizes, required section headings, etc. Proposers should ensure that additional packages or settings do not change the template formatting. Details can be found on JWST Preparing the Proposal PDF Attachment. Proposals that have changed the template formatting will be disqualified from the review. 

The "Technical Justification" section has been renamed "Description of Observations" this cycle. The required contents of this section have not changed.

New Habitable Worlds Observatory Precursor Science (HPS) initiative

STScI is introducing a new Habitable Worlds Observatory (HWO) Precursor Science (HPS) initiative, aimed at encouraging observations with JWST that will help guide HWO's science cases and early development. For more information, see JWST Special Initiatives.

Multi-cycle Joint JWST-HST observing proposals are allowed

Joint JWST-HST proposals are permitted to be multi-cycle in nature for both JWST and HST observations, either as a Future Cycle or LTM program, with some caveats. More information can be found in the Joint JWST-HST Observing Programs section of the JWST Additional Flags for GO Proposals page.

New requirement for Joint JWST-NRAO observing proposals

The PI of any Joint JWST-NRAO proposals must fill out the following NRAO short form, consisting of high-level metadata, within one week of the JWST Cycle 6 proposal deadline.

Analysis Plans are optional for Combined GO+AR proposals

While Combined GO+AR proposals must describe both the new and archival observations, and they must include a "Description of Observations" section for the new data, the inclusion of a separate "Analysis Plan" section for the archival data is optional. See the Combined GO+AR section of the JWST Additional Flags for GO Proposals page for more information.

Pure Parallel proposers must verify their observing scenario

Proposers are required to use the jwst-pure-parallel package to assess whether their specific observing scenario would have been viable in previous cycles. More information can be found on the JWST Parallel Observations page.

Instrument updates and new modes

NIRCam

NIRCam is offering a new readout strategy called Superstripe that allows for imaging of bright targets using the 64 × 64 subarray and the full frame detectors. This capability will be available in Cycle 6 in the Imaging and the Time Series Imaging modes.

The Rogue Path Tool is available for evaluating whether observations may be affected by the "claw" scattered light artifact. In previous cycles, claws were addressed as part of the Instrument Scientist review. In Cycle 6, proposers will be responsible for assessing their observations using the tool.

NIRSpec

NIRSpec is offering four new superstripe subarrays in the Bright Object Time Series template when using the prism disperser. These superstripe subarrays enable prism spectroscopy of brighter targets without saturation.

MIRI

MIRI will be offering a suite of new subarrays in the Imager detector array, which are unaffected by Electromagnetic Interference (EMI) noise, and two new subarrays for the Low-Resolution Spectroscopy (LRS) modes (one for slitless and one for slit). Old subarrays will remain available for observers in Cycle 6, with a goal to deprecate them in Cycle 7. Full details of MIRI’s new subarrays can be found on the MIRI JDOX pages.

MIRI will offer the FASTGRPAVG8 detector readout pattern to improve the signal to noise relative to the SLOWR1 mode. SLOWR1 will remain available in Cycle 6, with a goal to retire the pattern in Cycle 7.

MIRI Wide Field Slitless Spectroscopy (WFSS) is now available for Coordinated and Pure Parallel observing modes. Coordinated Parallel observations are now possible with MIRI WFSS as prime and NIRCam imaging as parallel.

APT updates

APT version

Cycle 6 proposers should use the Astronomer's Proposal Tool (APT) version 2026.3.2 or higher for proposal preparation, released on July 9, 2026. Details can be found in the release notes (for current and past versions). Proposers can generate programs in APT using previous versions, but will need to update to version 2026.3.2 or higher before final submission. 

APT support

Starting with Cycle 6, APT will only support operating systems that are still supported by their vendor. For more details and specifics about which operating systems are supported, see the APT installation pages (apt.stsci.edu).

Renamed PDF previews

When you choose the PDF Preview tool, you will now have three options:

• "TAC PDF" shows you the exact PDF file that will be given to the reviewers;
• "STScI PDF" is the full PDF file submitted to STScI (including the Observing Description, Investigators, and Team Expertise); and
• "Operational PDF" is the more detailed operational view with full specifications of targets, observations, and any diagnostics.

New instrument modes and keywords

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

APT supports the updated science categories and keywords; please see Science category and keyword updates above for details.

ETC updates

ETC version

Cycle 6 proposers should use the JWST Exposure Time Calculator (ETC) version 6.0, released on July 16, 2026.  Updates for version 6.0 include:

• updated thermal background levels,
• updated MIRI throughputs,
• added support for new MIRI imager and LRS subarrays (see the MIRI Instrument Updates above),
• added support for the new MIRI FASTGRPAV8 readout mode (see the MIRI Instrument Updates above),
• added support for NIRCam Imaging and NIRSpec BOTS Prism superstripe modes (see the NIRCam Instrument Updates above),
• improved background modeling for MIRI and NIRISS SOSS modes,
• updated PSFs,
• revised calculation defaults and sample/science workbooks,
• several user interface and backend performance enhancements.

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 6 projected behavior.

JWST Cycle 6 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.

Next: JWST Key Policies