Hubble Space Telescope Call for Proposals for Cycle 34
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
April 6, 2026:
APT Submission Portal Closure: Proposers are reminded that the APT submission portal will close at the submission deadline of April 16, 2026 at 8pm. Late submissions or resubmissions will not be accepted. In exceptional circumstances, proposers requiring an extension should make a request via the Help Desk before the deadline.
DD Submission Downtime: The APT submission portal will be closed from April 16, 2026 at 8pm until April 17, 2026 at 12pm. During the closure period it will not be possible to submit HST Director’s Discretionary (DD) proposals. Please plan accordingly.
- April 1, 2026:
- Reminder: ACS/WFC and WFC3/IR are available: ACS/WFC and WFC3/IR are anticipated to remain available and fully supported in Cycle 34. While the Call for Proposals notes that these modes “may be offered as shared risk” in future cycles, “shared risk” does not mean the instruments would be unavailable or poorly calibrated. Proposers with science goals best served by ACS/WFC or WFC3/IR are encouraged to propose for these modes in Cycle 34. More details can be found in the ACS February STAN and the WFC3 March STAN.
- February 26, 2026:
- There is a new requirement for Joint HST-NRAO proposals. Within one week of the HST Cycle 34 proposal deadline, the PI must fill out the following NRAO short form, consisting of highlevel metadata.
- February 19, 2026:
- LaTeX templates updated to ensure the PDF attachment document is Letter size. Overleaf now uses a European LaTeX distribution which produces documents in A4 size by default. Make sure to use the most recent version of the PDF attachment templates. Using an older template could cause the proposal to be disqualified.
- January 26, 2026:
- Starting in Cycle 34, single guide star (1GS) guiding will become the default for ACS/WFC and WFC3 observations with exposure times < 1001s in visits with length of 1 or 2 orbits (not including moving targets or spatial scans). There will be an opportunity to opt-out of 1GS with a strong scientific justification after Phase II notifications are sent out. Further information about 1GS is available in WFC3 ISR 2025-07.
- January 16, 2026:
- Word templates updated: Make sure to use the most recent version of the PDF attachment templates. Using an older template could cause the proposal to be disqualified.
- December 18, 2025:
- APT Released: APT version 2025.7.2 is now available. Any HST proposals started in earlier APT versions should now be edited and submitted in this version.
See also HST New and Important Features.
Announcement
Release Notice: December 12, 2025
We are pleased to announce the Cycle 34 Call for Proposals for Hubble Space Telescope (HST) observations and funding for archival research programs. Participation in this program is open to all categories of organizations, both domestic and foreign, including educational institutions, profit and nonprofit organizations, NASA Centers, and other Government agencies. Cycle 34 will extend from November 1, 2026 - October 31, 2027. We will accept proposals for the following instruments: ACS, COS, FGS, STIS, and WFC3. This solicitation for proposals will be open through Thursday, April 16, 2026 at 8:00pm EDT. The Astronomer's Proposal Tool (APT), which is required for Phase I Proposal Submission, will be made available for Cycle 34 Phase I use in early 2026. Results of the selection will be announced by late July 2026. Questions can be addressed to the STScI HST Help Desk (https://hsthelp.stsci.edu).
Welcome
We invite scientists to participate in Cycle 34 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 2700 orbits in this cycle, including approximately 1350 orbits for Very Small and Small Programs, 675 orbits for Medium Programs, and 675 for Large and Treasury Programs. An additional 1500 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), Archival Research (AR), and Snapshot (SNAP) programs in Cycle 34. The table of contents for the web version of this document is on the right side of the page. The top right panel "On this Page" gives the contents of the current page. The bottom right panel contains the directory structure or tree of the "HST Proposal Opportunities and Science Policies" pages, and contains links that 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 34") within this directory. The tabs and drop down menus at the top, direct you to other sections of the HST User Documentation (e.g., "Instrument Handbooks").
Proposing Calendar and Deadlines
Cycle 34 Dates: November 1, 2026 - October 31, 2027
Cycle 34 Phase I proposal deadline: Thursday, April 16, 2026 at 8:00pm EDT
Cycle 34 Peer Review meeting: June 22 - July 1, 2026
Cycle 34 Phase II proposal deadline: anticipated August 13, 2026 at 5:00pm EDT
Cycle 34 Budget submission deadline: end-August 2026, for planning purposes only
Notification of the outcome of the Phase I selection process will be sent to all proposers in late July 2026.
What's New for Cycle 34
See HST New and Important Features.
Important Resources
- Read this Call for Proposals, which summarizes the policies and procedures for proposing in the current cycle of HST observing, including requests for research funding on archival HST data.
- The Hubble Space Telescope Primer for Cycle 34 provides an overview of the Hubble Space Telescope, with basic information about the telescope operations, instrument capabilities, and technical aspects of the proposal preparation process.
- Read the STScI HST Phase I Proposal Roadmap and the HST Phase II Proposal Roadmap for guidance on your Phase I and Phase II, respectively.
- Templates for the Proposal PDF attachment can be found on the HST Preparation of the PDF Attachment page.
- Visit STScI’s website at http://www.stsci.edu/ for more information about STScI.
- Register, verify, or update your STScI Single Sign-On (SSO) Account, needed for submitting your proposal and downloading proprietary data.
- For any concerns or an overview of how HST and JWST overlap, see Guidelines for Proposals where JWST and HST Overlap in Capabilities.
- Contact the STScI HST Help Desk (https://hsthelp.stsci.edu) to submit questions, concerns, or feedback on HST instruments, software, or policies.
Who's Responsible
The HST Call for Proposals and related materials for Cycle 34 were edited by Amy Jones. The Associate Director for Science, Mercedes López-Morales, and the Science Policy Division (SPD) at STScI are responsible for the oversight of the HST science program selection process. SPD members include Laura Watkins (SPD Head), Claus Leitherer (Hubble Science Policy Lead), Molly Peeples (Cross-Mission Policy Scientist), Daniel D'Orazio, Rebecca Levy, Joshua Lothringer, Amaya Moro-Martín, Nikolay Nikolov, Lou Strolger, 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