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


Release Notice: December 13, 2023

We are pleased to announce the Cycle 32 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 32 will extend from  October 1, 2024 to September 30, 2025. We will accept proposals for the following instruments: ACS, COS, FGS, STIS, and WFC3.

We anticipate allocating up to 3200 orbits in this cycle. See Hubble Space Telescope Call for Proposals for Cycle 32 for further details.  

This solicitation for proposals will be open through Tuesday March 26, 2024 at 8:00pm EDT. The Astronomer's Proposal Tool (APT), which is required for Phase I Proposal Submission, was made available for Cycle 32 Phase I use in January, 2024. Results of the selection will be announced by mid-late June.

Questions can be addressed to the STScI HST Help Desk (https://hsthelp.stsci.edu). 

The Cycle 32 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 32 for more information.

The Hubble Space Telescope Primer for Cycle 32 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

  • Wednesday March 6, 2024:
    • Duplications of Carry-Over ToOs: Where new ToO requests duplicate ToOs in programs from previous cycles, triggers from the previous-cycle ToOs have priority over the newly-proposed ToOs.  Proposers must identify and justify any requests for duplicate ToOs.  For more information, see Carry-Over ToOs. 
  • Tuesday March 5, 2024
    • The Hubble Advanced Spectral Products (HASP) initiative transforms the accessibility and utility of archival Hubble Space Telescope (HST) data by automating the coaddition and abutment of one-dimensional spectra from the Cosmic Origins Spectrograph (COS) and Space Telescope Imaging Spectrograph (STIS). HASP provides data products at both visit and program levels, covering all COS and STIS spectra, for each CENWAVE and grating. This service is regularly updated with the latest calibrations and new data from over 3200 programs and 64000 datasets. Additionally, HASP enables users to perform custom coadditions through interactive Jupyter Notebooks. For more details, visit the HASP webpage or Instrument Science Report.
  • Monday February 5, 2024:
    • Consecutive Observations: If your observations require a string of more than 6 consecutive orbits, that string will execute at shared risk (i.e., it will not be eligible for repeat if impacted by observatory problems).  Please consider alternative observational approaches to achieve your science goals.
    • Special Requirements: Given the current performance of the Hubble pointing control system, we remind proposers that all special requirements (such as timing and orientation constraints) not requested and justified in Phase I are implemented only under exceptional circumstances.  If this renders a science program infeasible, the program risks termination.
    • HST-JWST Joint Programs: New this cycle, we require JWST APT files to be submitted for joint HST-JWST programs. Failure to do so will result in disqualification of the proposal. See Joint HST-JWST Observing Programs and Joint HST-JWST Observations for more information.

See also HST New and Important Features.

Science Justification Templates

Templates for HST Cycle 32 Proposal PDF attachments:

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.

Download the PDF

Supporting Documents