Call for Proposals
The Call for Proposals describes the policies and procedures for submitting a Phase I proposal for HST Observing, Archival or Theoretical Research. Please read our guide to the use of electronic document formats.
Release Documents
- Full Set of HST Documentation
The Call for Proposals describes the policies and procedures for submitting a HST Phase I proposal. Get the CP as: PDF [US Letter Size], PDF [A4 Size], or as HTML.
The Primer provides an introductory overview of the Hubble Space Telescope and explains how to calculate the appropriate number of orbits for an observing proposal. Get the Primer as: PDF [US Letter Size], PDF [A4 Size], or as HTML.
Science Justification Templates for Cycle 24 HST Phase I
HST Phase I Roadmap
DD Time
Up to 10% of the available HST observing time may be reserved for Director's Discretionary (DD) allocation.
Mid-Cycle Proposals
Up to 200 orbits per cycle will be available for Mid-Cycle GO programs. Mid-Cycle programs were initiated in Cycle 23 to provide the community with an opportunity to propose for in-cycle observations of recently-discovered, non-variable objects. As such, they complement Director’s Discretionary programs, which target unexpected transient phenomena and time-critical observations..