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Hubble Space Telescope

Phase II Proposal Instructions

The Phase II Proposal Instructions are available as PDF documents (you need the Acrobat reader). Two formats are provided: 8.5x11 for US readers and an A4 format for elsewhere.

STScI is no longer printing the Phase II Proposal Instructions (P2PI) and we do not maintain an inventory of copies. This saves on wasted paper, but, more importantly, the electronic document has extremely useful features that paper cannot reproduce. These include a fully-linked table of contents and index, navigation buttons on each page, and many cross-references.

We urge you to try the document on-screen first. You have several ways to access the PDF files for reading:

  1. Recommended: Click to download the US or A4 versions. Your browser will open a dialog box and ask for a file name. Place the file in a location convenient to you, and then you can open the file in your browser by typing a URL of the form: file:[your-directory-name]/p2pi.pdf
    If this does not work, click on the above links with your right mouse button and pull the menu down to "Save Link As...".
  2. You can get the PDF files by anonymous ftp with these steps:
    • cd to your local directory where you wish to place the file
    • ftp
    • login as "anonymous," use your e-mail address as password
    • cd outside-access/out.going/p2pi
    • binary
    • get p2pi.pdf (or p2pi_A4.pdf)
    • quit

    After transferring the files, you open them in your browser as "file:..".

  3. Click to open the file directly. When you do this, the files are downloaded to your computer, but to a temporary area where you cannot save them. However, as long as you leave the Acrobat reader open you should have no problem.

The Acrobat reader can be downloaded for free from Once you are in the document it is easy to print selected pages for ready reference (use Ctrl-p).

If you still want a paper copy after you try this, please realize we will do exactly what you would anyway: print it out on a laser printer, stick it in an envelope, and drop it in the mail. Send requests for paper copies to

Release Documents

    The Call for Proposals describes the policies and procedures for submitting a HST Phase I proposal. Go to the CP.

    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. Go to the Primer.

    Science Justification Templates for Cycle 26 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