STScI solicits proposals for HST Observing, Archival, and Theoretical Research. The full details are made available through two documents, the Call for Proposals, and the HST Primer. Downloadable PDF collections of these articles are provided as a courtesy, made available and updated when feasible. The online documentation is the authority, and will be updated with the latest information.

Late Breaking News

Welcome

We invite scientists to participate in Cycle 33 of the Hubble Space Telescope (HST). The telescope and its instruments were built under the auspices of the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA). Management of HST’s scientific program is carried out by the Space Telescope Science Institute (STScI). We anticipate allocating up to 2600 orbits in this cycle, including approximately 1300 orbits for Very Small and Small Programs, 650 orbits for Medium Programs, and 650 for Large and Treasury Programs. An additional 1000 Snapshot observations and 500 Pure-Parallel observations may be allocated. Abstracts of previously accepted programs can be found on the HST proposal catalogs webpage.

This document establishes the goals, requirements, and policies for General Observer (GO) and Archival Research (AR) programs in Cycle 33. The table of contents for the web version of this document is on the right side of the page, and links there can take you to any page from any other page (click the arrow to expand the entire table of contents under "Hubble Space Telescope Call for Proposals for Cycle 33"). The links at the top of each page correspond to sections within that given page.

Proposing Calendar and Deadlines

Cycle 33 Dates: November 1, 2025 - October 31, 2026

Cycle 33 Phase I proposal deadline: Thursday, April 10, 2025 at 8:00pm EDT

Cycle 33 Peer Review meeting: June 23 - July 3, 2025

Cycle 33 Phase II proposal deadline: anticipated August 14, 2025 at 5:00pm EDT

Cycle 33 Budget submission deadline: August 14, 2025 at 5:00pm EDT

Notification of the outcome of the Phase I selection process will be sent to all proposers in late July 2025.

What's New for Cycle 33

See HST New and Important Features.

Where to Get Help

Read this Call for Proposals and The Hubble Space Telescope Primer for Cycle 33.
Visit the STScI HST Phase I Proposal Roadmap and the HST Phase II Proposal Roadmap.
Visit STScI’s website at http://www.stsci.edu/.
Register (or review/check) a STScI Single Sign-On (SSO) Account.
Contact the STScI HST Help Desk (web: https://hsthelp.stsci.edu).

Who's Responsible

The HST Call for Proposals and related materials for Cycle 33 were edited by Molly Peeples (Hubble Science Policies Deputy). The Associate Director for Science, Mercedes López-Morales, and the Science Mission Office (SMO) at STScI are responsible for the oversight of the HST science program selection process. SMO members include Marc Postman (SMO Mission Head), Laura Watkins (SMO Deputy Mission Head), Claus Leitherer (Hubble Science Policies Lead), Katey Alatalo, Daniel D'Orazio, Andrew Fruchter, Amy Jones, Susan Kassin, Rebecca Levy, Amaya Moro-Martin, Nikolay Nikolov, Jamila Pegues, Linda Smith, and Technical Manager Aleksandra Hamanowicz. Neill Reid (Multi-Mission Project Scientist) participates in an advisory capacity.

Download the PDF

This PDF is provided as a courtesy, made available and updated when feasible. The online documentation is the authority, and will be updated with the latest information.

Next: HST New and Important Features

Hubble Space Telescope Call for Proposals for Cycle 33