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Proposal Support

The Hubble Space Telescope (HST) proposal process involves various steps, which are summarized below. For more details please check this page.

  • Call for Proposals

    The Call for Proposals (CP) invites the astronomical community to propose for observing time on HST in a given cycle (nominally one year in duration). It summarizes the policies and procedures for proposing in that cycle of HST observing, including requests for funding research on archival HST data. A CP for a given cycle is issued approximately a year before the nominal start of the cycle.

  • Phase I: Writing and submitting a proposal for HST observing time

    The CP describes in detail the policies and procedures for submitting a Phase I proposal for HST. Proposers should also consult all relevant technical documentation about the capabilities and sensitivities of the instrument(s) to be used in their programs and should discuss the requirements of their observing programs with appropriate Space Telescope Science Institute (STScI) experts. Contacts are provided via the STScI Help Desk at To avoid duplication conflicts proposers also should consult up-to-date exposure ASCII catalogs and the Duplication Checking Web Form.

  • Phase II: Providing the details

    A Telescope Allocation Committee (TAC), organized by the STScI, reviews and evaluates the submitted Phase I proposals. The TAC recommends a list of programs to the STScI Director for preliminary approval and implementation. Upon final approval by the Director, a successful proposal enters into the Phase II stage of proposal preparation, during which proposers must provide the details required by the ground system to schedule HST and obtain their observations.

Most HST observations have proprietary periods of one year, during which the data are only accessible to the proposers. More details on HST proprietary rights are available.