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Hubble Space Telescope

Special Opportunities

If you have an idea for an observation that requires immediate consideration, please submit a request for Director's Discretionary Time.

Release Documents

    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 25 HST Phase I

  • Full Set of HST Documentation

HST Phase I Roadmap

    The Roadmap is a step-by-step guide to proposing and submitting an HST proposal. Download APT here.

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..

Special Programs from Past Cycles

Status of Current and Past Programs:

Past Proposal Opportunities