About this Article

Amaya Moro-Martín (amaya[at]stsci.edu) and Alexandra Hamanowicz (ahamanowicz[at]stsci.edu) for the JWST Science Policy Division

Published April 21, 2026

The Cycle 5 Science Program is comprised of 254 proposals, including 227 General Observer (GO) proposals, for a total of 8,009 prime hours of which 2,275 hours (28%) have a zero Exclusive Access Period. This set includes the proposals recommended by the Galactic and Extragalactic Executive Committees.

A full description of the proposal selection process and results appears in the article, JWST Cycle 5 Proposal Selection. A full summary of the approved proposals statistics is posted on the JSTUC webpage toward the top, titled: Summary of the Results from the JWST Cycle 5 TAC.

Recommended Large Proposals

The Composition and Origins of the Main-Belt Asteroids
GO 11793, Large GO, 143.7 hours, PI: Katherine de Kleer (California Institute of Technology)
MIRI/MRS and NIRSpec spectroscopic study to reveal precise silicate composition and the presence of hydrated and ammoniated minerals and organics in the surfaces of 49 asteroids. The goal is to answer questions regarding the condensation region of objects within our solar system’s protoplanetary disk and the processes of volatile incorporation, melting, and differentiation in the planetesimals, placing it in the context of extraplanetary systems.

IN/AT-SYNC: INterior/ATmosphere SurveY of sub-Neptunes in Chains
GO 10047, Large GO, 196.4 hours, PI: Rafael Luque (Instituto de Astrofísica de Andalucía)
NIRISS/SOSS and NIRSpec/G395H observations to measure the atmospheric mean molecular weights, C/O ratios, and envelope mass fractions for nine sub-Neptunes in resonant chains orbiting Sun-like stars. Combined with existing JWST data, the program will obtain a finely sampled age sequence (20 Myr to 7 Gyr) to test how interior–atmosphere coupling evolves from early atmospheric mass-loss to magma-ocean equilibrium and volatile exchange, to long-term cooling. The program will deliver the first comprehensive view of sub-Neptune evolution around Sun-like stars, linking interior physics, atmospheric chemistry, and dynamical history.

Parting the Clouds: An optimized limb-limb exoplanet survey to reveal diurnal cloud cycling and the mass-metallicity relation
GO 9709, Large GO, 182.5 hours, PI: David Sing (Johns Hopkins University)
NIRSPEC BOTS and NIRISS SOSS observations to obtain the first comprehensive limb-resolved panchromatic survey of gas giant exoplanets will disentangle the cloudy morning terminator from the evening, addressing the large biases in transit-derived metallicity measurements introduced by large cloud-asymmetries. This program will test the hypothesis that diurnal cloud cycling causes widespread limb-asymmetries in transiting exoplanets and measure the mass-metallicity trend for gas giants using accurate unbiased metallicities, making a significant impact on both the atmospheric dynamics of exoplanets and the field of planet formation.

A definitive test of the Hubble tension: independent of the local distance ladder
GO 9637, Large GO, 139.5 hours, PI: Tommaso Treu (University of California, Los Angeles)
Aims to resolve the Hubble tension by using strong lensing gravitational time delays to measure the Hubble constant independently of that derived from both local cosmic distance ladder and early universe probes. The program will obtain NIRSpec IFU data of 11 lenses (and NIRcam imaging of six of them) that, together with ancillary data and archival observations of seven additional lenses, will be able to achieve a 1.5% precision. The observations will also enable studies of massive galaxy evolution, the lensed black hole and host galaxy correlation, and the nature of dark matter.

Massive stars in the first gigayear revealed with an ultra-deep NIRSpec stare
GO 12435, Large GO, 139.2 hours, PI: Peter Senchyna (Carnegie Institution of Washington)
NIRSpec G140 observations to construct the highest-quality rest-UV spectroscopy possible for a statistical sample of z = 7-9 galaxies with the goal of assembling the first detailed picture of massive stars and their impacts in the reionization era.

MIRAGE: MIRI Investigation of Red and Ancient Galaxies in the Early Universe
GO 10202, Large GO, 156.5 hours, 120.1 parallel hours, PI: Steven Finkelstein (University of Texas at Austin)
Deep MIRI imaging at 5-10 micron of the HUDF and surrounding region to probe the obscured phases of galaxy evolution at z > 7, improving constraints on stellar mass, star-formation rate, and dust attenuation, directly distinguishing between competing models for dust formation at early times. The program will also enable the discovery of the first robust sample of Little Red Dots at z > 9, and the characterization of their larger population at z < 9. MIRAGE parallel observation with NIRCam 3-5 micron slitless spectroscopy will cover the NGDEEP+MIDIS region to measure redshifts at z = 5-9 and discover new supermassive black holes.

The Core of the Iceberg: the Physics of Sub-L* Galaxies in the First Billion Years
GO 9645, Large GO, 169.3 hours, PI: Tommaso Treu (University of California, Los Angeles)
NIRSpec R~1000, 1–5 micron ultradeep spectroscopic survey of > 120 faint sources at z > 6, magnified by the best-characterized lensing cluster Abell 2744, to detect UV and optical emission line diagnostics that trace C, N, O abundance, escape fraction, and AGN activity. The goal is to carry out the first measurements of the ionizing radiation field, star formation history, dust content, and detailed chemical enrichment for the sub-L* population at z > 6.

Resolving Stellar Feedback in Action via NIRCam and MIRI Imaging of Very Nearby Galaxies
GO 10046, Large GO, 159.4 hours, PI: Adam Leroy (Ohio State University)
NIRcam and MIRI imaging covering four of the closest (D < 5 Mpc) galaxies, NGC 253, 300, 5236 and 7793, to resolve tracers of star formation and feedback on 1-10 pc scales. Combining JWST, ALMA, and VLT+HST data, these observations will resolve > 50,000 star-forming regions across all stages of their evolution to address open questions surrounding star formation and the gas-star feedback cycle. 

Recommended Treasury Proposals

The JWST Spectral Library for Cool Stars
GO 11441, Medium Treasury GO, 79.7 hours, PI: Mark Giampapa (University of Arizona)
High-resolution NIRSpec spectroscopic observations of 43 carefully selected magnetically quiescent stars (3,200 K to 5,000 K) across a broad metallicity range. The goal is to establish a JWST Spectral Library for Cool Stars, providing high-precision, flux-calibrated spectra critical for validating and refining current stellar atmosphere models. This library will allow accurate transmission spectrum corrections that will enhance atmospheric characterizations of rocky planets and the modeling of cool stellar atmospheres.

Binaries In the Galactic Center: an Astrophysical Treasury Survey (BIGCATS)
GO 10961, Medium Treasury GO, Roman Preparatory Science, 36+36+36 hours, PI: Jessica Lu (University of California, Berkeley)
Multi-epoch spectroscopy and radial velocities of the central 9'' (0.36 pc) of the Galactic Center, and multi-epoch photometry and astrometry of the central 2' (4.8 pc) using NIRSpec and NIRCam. Combined with archival JWST data, the observations will provide the most complete census of binary and compact object populations around a supermassive black hole (SMBH) to study how often black hole (BH) binaries form, merge, and grow around the SMBH, what is the total mass of the BH population, and how often do stellar binaries close to the SMBH lead to hypervelocity stars, tidal disruption events, and mergers.

The JWST/NIRCam Legacy Survey of the Galactic Center
GO 10678, Large Treasury GO, Roman Preparatory Science, 143.2 hours, 4 hours parallel, PI: Rainer Schoedel (Instituto de Astrofisica de Andalucia)
Large-area two-filter survey with NIRCam of the inner R~100 pc of the Galaxy to characterize the Galactic Center (GC) stellar population with unprecedented precision. This program will deliver high-level data products, including catalogs cross-matched with other GC surveys, saturation-corrected images, and tools optimized for crowded-field photometry. The goal is to study the 3D structure and kinematics of the gas and stars, how the long history of sporadic star formation relates to the overall history of the Milky Way, what is the driving force behind the observed super-wind, and how extreme conditions affect the (non)universality of star formation. 

Recommended Archival Research Legacy Proposals

Increasing the sensitivity of all high-contrast imaging through physics-based PSF subtraction and automatic differentiation
AR 11751, AR Legacy, PI: Rodrigo Ferrer-Chavez (Northwestern University)
This program aims to reprocess all exoplanet direct-imaging NIRCam and MIRI observations with a new physics-based PSF subtraction algorithm enabled by machine learning optimization tools to increase the exoplanet detection sensitivity. Early results of this method on NIRCam data have shown improvements by at least a factor of three in exoplanet detection sensitivity relative to traditional algorithms. This open-source tool will be made available to the community, paving the way its application in future JWST high-contrast imaging and other JWST modes.

The Faint Frontier: Pushing Proper Motion Limits with JWST+Gaia
AR 12274, AR Legacy, PI: Kevin McKinnon (University of Toronto)
This program will construct an open-source tool, GaiaWebb, that will combine JWST images (NIRCam, NIRISS, and MIRI) with Gaia data to measure stellar astrometry with an order of magnitude better precision than Gaia alone, providing the first proper motions for the faintest stars (G > 20.7 mag). The tool will enable studies of Local Group kinematics and dynamics, which will constrain models of dark matter and galactic formation and evolution.

Resolving Galaxy Evolution: A Public Framework for JWST Slitless Spectroscopy 
AR 11074, AR Legacy, Roman Preparatory Science, PI: Vicente Estrada-Carpenter (Arizona State University)
This program will develop and publicly release a pipeline that produces emission-line maps from all available NIRISS and NIRCam Wide Field Slitless Spectroscopy (WFSS) data. Its goal is to provide the first statistically-representative view of how internal structure drives galaxy evolution, linking JWST imaging and spectroscopy, and laying the foundation for spatially-resolved analysis of future Roman grism surveys.

Recommended Pure Parallel Proposals

LAPIS: Large Area Parallel Imaging Survey 
GO 10790, Pure Parallel, 1,000 parallel hours, PI: Sandro Tacchella (University of Cambridge)
NIRCam survey of 100 independent sightlines (1,000 arcmin^2) targeting UV-bright galaxies, aimed to uncover the first generation of galaxies at z > 16. The goal is to constrain the UV luminosity density, dust content, and morphology of the earliest galaxies, providing the first robust census of luminous systems at z > 16.

The JWST Cycle 5 science program includes a wide variety of smaller-scale observational programs, each addressing key science questions. Information about all the approved proposals — including 40 Medium programs, 70 Small programs, and 105 Very Small programs — is available in the Cycle 5 GO page. 

A heartfelt thank you to all JWST proposers for an unprecedented brainstorming that has resulted in a Cycle 5 Science Program that ensures that JWST will continue to enable groundbreaking work across all areas of astrophysics.

Review All of JWST's Approved Programs