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Hubble Space Telescope
Cycle 25 Announcement

Release Notice: January 13, 2017

NASA and The Space Telescope Science Institute (STScI) are pleased to announce the Cycle 25 Call for Proposals for Hubble Space Telescope (HST) Observations and funding for Archival Research and Theoretical 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 25 will extend from October 1, 2017 to September 30, 2018. We will accept proposals for the following instruments: ACS, COS, FGS, STIS, and WFC3.

This solicitation for proposals will be open through April 07, 2017 8:00pm EDT. The Astronomer's Proposal Tools (APT), which is required for Phase I Proposal Submission will be made available/released for Cycle 25 Phase I use during the last week of January 2017. Results of the selection will be announced by the end of June 2017.

Questions can be addressed to the STScI Help Desk (email:; phone: 410-338-1082).


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