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Hubble Space Telescope
Cycle 24 Announcement

Release Notice: January 13, 2016

NASA and The Space Telescope Science Institute (STScI) are pleased to announce the Cycle 24 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 24 will extend from October 1, 2016 to September 30, 2017. We will accept proposals for the following instruments: ACS, COS, FGS, STIS, and WFC3.

This solicitation for proposals will be open through April 08, 2016 8:00pm EDT. The Astronomer's Proposal Tools (APT), which is required for Phase I Proposal Submission will be made available/released for Cycle 24 Phase I use during the 2nd week of February 2016. Results of the selection will be announced by the end of June 2016.

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


  • Phase I Proposals: Friday April 8, 2016 8:00 pm EDT
  • Phase II Proposals & Budgets: Thursday July 21, 2016

Late Breaking News

What's New for Cycle 24

Proposal Opportunity Updates

Proposal Format Updates

Changes in the Proposal Review Process

New Supported Instrument Capabilities

Important Features Carried Over From Cycle 23

Click here for details on these and other changes for Cycle 24

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 24 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..

Past Proposal Opportunities