The Hubble Space Telescope Primer for Cycle 32

The HST Primer provides an introduction to the Hubble Space Telescope for Phase I proposers.

About This Document

The Hubble Space Telescope (HST) Primer for Cycle 32 is a companion document to the Hubble Space Telescope Call for Proposals for Cycle 32. It provides an overview of HST, with basic information about telescope operations, instrument capabilities, and technical aspects of the proposal preparation process. A thorough understanding of the material in this document is essential for the preparation of a competitive proposal. The Call for Proposals discusses the policies and procedures for submitting a Phase I proposal for HST observing or archival research. Technical documentation on the instruments are available in their respective handbooks, available on the HST Document overview site.

Late Breaking News

  • Wednesday July 10, 2024:
    • Reduced Gyro Mode (RGM): Hubble has transitioned to RGM. As a result of this transition:
      • The Cycle 32 Phase II deadline has moved to August 16, 2024. PIs of accepted programs should see the emails from their Program Coordinators for more information.
      • The Cycle 32 Budget deadline will move from its previously-advertised date, the new date is TBD.
      • The Cycle 32 dates have shifted to November 15, 2024 - October 31, 2025.
      • More information about RGM can be found at Reduced Gyro Mode Tips and Resources
    • Operational Paradigm Change Review (OPCR): Not related to the above, NASA is also undergoing an OPCR for Hubble. More information can be found at NASA Hubble Operational Paradigm Change Review and Hubble Observations.
  • 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.

Proposing Calendar and Deadlines

  • Cycle 32 Phase I proposal deadline: Tuesday March 26, 2024 at 8:00pm EDT

  • Cycle 32 Peer Review: May 28 - June 5, 2024

  • Cycle 32 Phase II proposal deadline: Friday August 16, 2024

  • Cycle 32 Budget deadline: TBD at 5:00pm EDT

  • Cycle 32 Mid-Cycle Deadline: TBD

Where to Get Help

Submit questions to the HST Help Desk at See for additional tools and resources.

Who's Responsible

The HST Call for Proposals and related materials for Cycle 32 were edited by Jamila Pegues. The Associate Director for Science, Neill Reid, and the Science Mission Office (SMO) at STScI are responsible for the oversight of the HST science program selection process. SMO members include Alessandra Aloisi (SMO Mission Head), Elena Sabbi (SMO Deputy Mission Head), Laura Watkins (SMO Deputy Mission Head), Claus Leitherer (Hubble Science Policies Lead), Katey Alatalo, Christine Chen, Andrew Fruchter, Amaya Moro-Martin, Jamila Pegues, Linda Smith, and Technical Managers Brett Blacker and Aleksandra Hamanowicz.

Next: HST Primer: Resources, Tools, and Other Documentation