The Hubble Space Telescope Primer for Cycle 31

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 31 is a companion document to the Hubble Space Telescope Call for Proposals for Cycle 31. 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

  • No news is good news!

See also HST New and Important Features.

Proposing Calendar and Deadlines

  • Cycle 31 Phase I proposal deadline: Wednesday May 24, 2023 at 8:00pm EDT

  • Cycle 31 Peer Review: August 1-9, 2023

  • Cycle 31 Phase II proposal deadline: September 15, 2023

  • Cycle 31 Budget deadline: September 28, 2023 at 5:00pm EDT

  • Cycle 31 Mid-Cycle Deadline: TBD at 11:59pm EST

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 31 were edited by Laura Watkins and Molly Peeples. 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), Molly Peeples (Hubble Science Policies Deputy Lead), Katey Alatalo, Christine Chen, Andrew Fruchter, Amaya Moro-Martin, Jamila Pegues, Linda Smith, and Technical Manager Brett Blacker.

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