HST Proposal Opportunities and Science Policies
Articles in this section comprise the traditional Call for Proposals. These articles include information on observing and science policies, and details on the proposal submission process, including roadmaps.
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.
Current HST Proposal Opportunities
Announcement
Release Notice: December 18, 2024
We are pleased to announce the Cycle 33 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 33 will extend from November 1, 2025 to October 31, 2026. We will accept proposals for the following instruments: ACS, COS, FGS, STIS, and WFC3.
We anticipate allocating up to 2600 orbits in this cycle. See Hubble Space Telescope Call for Proposals for Cycle 33 for further details.
This solicitation for proposals will be open through Thursday, April 10, 2025 at 8:00pm EDT. The Astronomer's Proposal Tool (APT), which is required for Phase I Proposal Submission, will be made available for Cycle 33 Phase I use in February 2025. Results of the selection will be announced by mid-late July 2025.
Questions can be addressed to the STScI HST Help Desk (https://hsthelp.stsci.edu).
The Cycle 33 Call for Proposals
The Call for Proposals (CP) invites the astronomical community to propose for observing time on HST in a given cycle (nominally one year in duration). It summarizes the policies and procedures for proposing in that cycle of HST observing, including requests for research funding on archival HST data. See Hubble Space Telescope Call for Proposals for Cycle 33 for more information.
The Hubble Space Telescope Primer for Cycle 33 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.
Late Breaking News
- April 13, 2025:
- We will acknowledge receipt of proposals within 5 business days of the deadline.
- April 4, 2025:
- Shared Risk for ACS/WFC and WFC3/UVIS: As announced in HST New and Important Features, ACS/WFC and WFC3/IR are offered at shared risk in Cycle 33. A decision on their status will be made when the outcome of the senior review and subsequent budgetary direction from NASA HQ are known. If NASA does not allocate funding to continue fully supporting ACS/WFC and WFC3/IR, we anticipate that:
- Only basic calibration activities (anneals, superdark, and superbias updates for ACS/WFC; bad pixel updates for WFC3/IR) would be performed. The calibration accuracy would drift at a rate of a few tenths of a mmag per year.
- There would be no user support, meaning no contact scientist, no helpdesk, no documentation updates etc.
- HOPRs would not be allowed as there would be no staff to assess the quality of data in case of suspected observation failure.
- The use of ACS/WFC or WFC3/IR will not be penalized during proposal selection. However, in cases where the science can be equivalently achieved with WFC3/UVIS (for ACS/WFC) or JWST (for WFC3/IR), users are encouraged to use these modes. In cases where the science cannot be achieved with WFC3/UVIS or JWST, users should therefore briefly justify why the use of WFC3/UVIS or JWST is not possible and ACS/WFC or WFC3/IR is required.
- Shared Risk for ACS/WFC and WFC3/UVIS: As announced in HST New and Important Features, ACS/WFC and WFC3/IR are offered at shared risk in Cycle 33. A decision on their status will be made when the outcome of the senior review and subsequent budgetary direction from NASA HQ are known. If NASA does not allocate funding to continue fully supporting ACS/WFC and WFC3/IR, we anticipate that:
- April 1, 2025:
- Observations of Moving Targets: We have relaxed the restrictions on observations of moving targets. Visits will have a typical practical limit of about 6 contiguous orbits, but are no longer strictly limited to 2 contiguous orbits.
- Observations of Moving Targets: We have relaxed the restrictions on observations of moving targets. Visits will have a typical practical limit of about 6 contiguous orbits, but are no longer strictly limited to 2 contiguous orbits.
- March 25, 2025:
- New COS Lifetime Usage Policy: Starting in Cycle 33, COS FUV programs will be limited to a maximum of 2% lifetime usage per Lifetime Position (LP), with usage beyond 1% requiring justification in the Phase I proposal. Proposers should consult the updated lifetime usage table to determine whether their proposed observations approach or exceed the usage limits.
- New COS Lifetime Usage Policy: Starting in Cycle 33, COS FUV programs will be limited to a maximum of 2% lifetime usage per Lifetime Position (LP), with usage beyond 1% requiring justification in the Phase I proposal. Proposers should consult the updated lifetime usage table to determine whether their proposed observations approach or exceed the usage limits.
- February 3, 2025:
- New COS Lifetime Positions: Starting in Cycle 33, FUV gratings G130M utilizing cenwaves 1055, 1096, 1222, and 1291 and G160M utilizing all cenwaves will move to use new lifetime positions (LPs). Similar to previous moves, these LPs have different overheads and spectral resolution. More information is available in the March 2025 STAN.
- New COS Lifetime Positions: Starting in Cycle 33, FUV gratings G130M utilizing cenwaves 1055, 1096, 1222, and 1291 and G160M utilizing all cenwaves will move to use new lifetime positions (LPs). Similar to previous moves, these LPs have different overheads and spectral resolution. More information is available in the March 2025 STAN.
- January 9, 2025:
- APT: APT 2024.7.1 is now available. Cycle 33 proposers should use this version to submit their proposals. Submissions started in earlier versions can be transferred to 2024.7.1.
See also HST New and Important Features.
Science Justification Templates
Templates for HST Cycle 33 Proposal PDF attachments:
| Templates | LaTeX | Microsoft Word | output |
|---|---|---|---|
| GO | |||
| AR | |||
| GO/DD |
Note: the Word and LaTeX templates have intentionally different margins, to accommodate the same amount of text per page. See HST Guidelines and Checklist for Phase I Proposal Preparation for information on page limits.
See HST Preparation of the PDF Attachment for more information.