Cycle 3 Guaranteed Time Observations Call for Proposals

James Webb Space Telescope (JWST) Guaranteed Time Observations (GTOs) are awarded to scientists selected under AO 01-OSS-05 and through NASA-ESA-CSA agreements. GTOs with remaining allocations may submit GTO programs for Cycle 3.

On this page


We invite JWST Guaranteed Time Observers (GTOs) to submit Cycle 3 GTO science proposals. NASA policy requires that GTO Cycle 3 science proposals, including targets and observation specifications, be submitted by 2 months prior to the JWST Cycle 3 General Observer (GO) Call for Proposals. GTO targets and observing specifications will be ingested into the STScI archive and released to the community prior to the Cycle 3 GO Call for Proposals.

Proposing calendar and deadlines

Cycle 2 dates: July 1, 2023 to June 30, 2024

Cycle 3 GTO proposal deadline: June 28, 2023

Cycle 3 Call for Proposals: August 15, 2023

Cycle 3 dates: July 1, 2024 - June 30, 2025

GTO proposal submission

Teams should submit proposals using the Astronomer's Proposal Tool (APT). APT 2023.3 will be released as part of PPS 15.2 on May 18, 2023. Proposals should be completed by June 28, 2023. APT 2023.3 does not include the final capabilities that will be available for Cycle 3, so GTOs will have an opportunity to adjust and finalize their proposals prior to the Cycle 3 GO deadline.

Who's responsible

Members of the Science Mission Office at STScI are responsible for the oversight of the JWST science program selection process. The members involved include Neill Reid (Associate Director for Science), Alessandra Aloisi (Head, Science Mission Office), Laura Watkins (Deputy Head, Science Mission Office), Christine Chen (Lead, JWST Science Policies), Katey Alatalo (Deputy Lead, JWST Science Policies), Amaya Moro-Martin, Jamila Pegues, Elena Sabbi, Linda Smith, and Technical Manager Brett Blacker.

Where to get help

Submit questions to the JWST helpdesk at  Consult JWST documentation at, and see for additional tools and resources. 

Notable updates

Originally published