This page contains general information about the Hubble Space Telescope proposal process, the organization of this document, and links to useful information.

About this Document

Two documents are of primary relevance for HST proposers: this Call for Proposals for Cycle 33 and the HST Primer for Cycle 33. The Call for Proposals discusses policies and procedures, and explains how to submit a Phase I proposal. The Primer provides a basic introduction to the technical aspects of HST and its instruments, and explains how to calculate the appropriate number of orbits for your Phase I observing time requests.

The Call for Proposals is available electronically in HTML and PDF formats. The HTML version is optimized for on-line browsing, and contains many links to related or more detailed information, both within the document itself and in other STScI documents. You are therefore encouraged to use the HTML version electronically. Nonetheless, some people may prefer to read a hard copy, and with this in mind, the PDF version was optimized for printing.

General Guidelines for Proposal Preparation

• Explain why your science program is critically important, what impact it will have within its immediate subfield, what impact it will have outside of its immediate subfield, why it requires HST and any special requirements, and how it will acheive its science goals. See HST Proposal Selection Procedures for more information.
• Write for the appropriate audience. Review panels span a broad range of scientific topics and reviewers necessarily span a broad range of expertise. This is especially true of the Executive Committee that reviews the Large and Treasury proposals. Keep in mind that often reviewers with the closest expertise to the topic of the proposal have a conflict of interest with the proposal and are prohibited from its review. It is therefore crucial that your proposal provides sufficient introductory material for the non-specialist, and explains the importance of the program to astronomy in general.
• Explain clearly and coherently what you want to do and why. Make sure to get your point across to reviewers who have to judge many proposals in a few days.
• If you have a project that requires a significant investment of HST observing time, do not hesitate to propose it. Cycle 33 will be open to all proposal categories.
• It is the responsibility of the proposer to ensure that the proposed observations are technically feasible. Proposals that are not technically feasible will be rejected, so familiarize yourself with the technical documentation provided by STScI. (In particular, make sure that your observations do not exceed bright object safety limits in the Observing Considerations section of the HST Primer). Contact the STScI Help Desk if anything is not clear, or if you are unsure about the feasibility of a particular approach or observation. 
• Proposers who are eligible for NASA funding and intend to request funds for supporting resources, including support for ground-based observations or for the analysis of archived ground-based observations, should make those intents clear in the scientific justifications of their Phase I proposals. Proposers who are eligible for NASA funding and intend to request support for ancillary work, such as obtaining and analyzing ground-based observations or laboratory results, must state that intent in the scientific justification of their Phase I proposal. Budgets for all accepted programs will be subject to review and requests to cover costs that are not justified in the Phase I proposal will be judged out of scope and disallowed.

Resources, Documentation, and Tools

The Cycle 33 Announcement webpage provides links to information and documentation that will be useful to you while preparing your proposals. This page will also provide any late-breaking updates on the Phase I process, and answers to frequently asked questions. The Phase I Proposal Roadmap is a high level, step-by-step guide to writing a Phase I Proposal. Links to the appropriate sections of various documents (Call for Proposals, Primer, etc.) are given for each step. The The Hubble Space Telescope Primer for Cycle 33 provides a basic introduction to the technical aspects of HST and its instruments, and explains how to request the appropriate number of orbits in a Phase I proposal. The Instrument Handbooks are the primary source of information for the HST instruments. They can be found following the relevant links on the HST Instruments Page. You should use current versions of the Instrument Handbooks when preparing a proposal. They are available for all instruments, including former instruments that may be of interest for Archival Research. The Handbooks are distributed electronically, and can be accessed from the HST Documents webpage. This page also provides links to more detailed technical information, such as that provided in Instrument Science Reports.

For information regarding the overlap and complementarity of HST and JWST see Guidelines for Proposals where JWST and HST Overlap in Capabilities.

The Astronomer’s Proposal Tool (APT)

The Astronomer’s Proposal Tool (APT) is the interface for all Phase I and Phase II proposal submissions for HST. The current version of APT, along with minor bug fixes and enhancements, is essentially the same system as was used in the last cycle. See the "HST What’s New" button in APT for details on the changes. The APT webpage contains information on the installation and use of APT.
The Aladin Sky Atlas is available via APT. This interface can be used to display HST apertures on images of the sky. This tool brings a variety of benefits to users including access to a wide variety of images and catalogs. The GALEX catalog is available in Aladin to assist in checking for potentially dangerous objects for the UV detectors. Training documentation and videos can be found on the APT Training Materials page.

Exposure Time Calculators (ETCs)

STScI provides Exposure Time Calculators (ETCs) for each of the HST instruments. Please use those electronic tools to estimate how long you need to integrate to achieve the signal-to-noise ratio required for your project. The ETCs will also issue warnings about target count rates that exceed linearity and safety limits. The ETCs can be accessed from the HST ETC webpage.

HST Data Archive

The HST Data Archive is part of the Mikulski Archive for Space Telescopes (MAST). The HST Data Archive contains all the data obtained by HST. Completed HST observations from both General Observer (GO) and Guaranteed Time Observer (GTO) programs are available to the community upon the expiration of their exclusive access periods. Observations taken by Large, Treasury, and Large GO Pure Parallel programs generally carry no exclusive access period.

The HST Archive Page provides links to information about getting started, search and retrieval, documentation, etc. You can search for HST data using either of two main search pages: the dedicated HST search page or the Data Discovery Portal. The Canadian Astronomy Data Centre (CADC) and the European Space Astronomy Centre (ESAC) maintain copies of the HST science data.

The Hubble Legacy Archive (HLA) is a project designed to enhance science from HST data by augmenting the HST Data Archive and by providing advanced browsing capabilities. Features of the HLA include a preview viewer, an interactive image display, a footprint service, individual and combined and mosaicked images, improved astrometric positions, object catalogs, and selected grism extractions. The HLA is a joint project of the Space Telescope Science Institute, the European Coordinating Facility (ST-ECF), and the Canadian Astronomy Data Centre. It offers access to high-level HST products including composite images and interactive tools for previewing data products. The Primer contains more detailed information about the HLA.

The HLA also produces source lists for tens of thousands of HST images. The Hubble Source Catalog (HSC) combines these visit-based WFC3, ACS, and WFPC2 source lists from the HLA into a master catalog with roughly 300 million sources. Version 1 of the HSC was released in February 2015, Version 2 was released in the Fall 2016 and Version 3 was released in July 2018. The HSC is an invaluable resource for exploring a wide range of new archival proposals, a few potential examples of which are also included in the HST Cycle 33 Primer.

Proposers can use high-level data products in the HST Spectroscopic Legacy Archive (HSLA) to increase the scientific use of existing spectroscopic data. This archive contains “science grade” co-added spectra of all usable public data, combining exposures for each target from across visits, programs, and cycles. This data is organized into “smart archives” by target type (such as “hot stars” and “white dwarfs”) and by scientific purpose (“IGM absorption sources”) so that samples can be readily constructed and downloaded without manual interaction with MAST. The third generation of these products that include FUV and NUV modes of COS is available on line via MAST. For STIS observations or more recent COS data, proposers can also make use of the default Hubble Advance Spectral Products (HASP) in the archive to increase the scientific use of existing spectroscopic data. More details are available at https://archive.stsci.edu/missions-and-data/hst/hasp. 

Questions about the Archive and archival data should be sent to the Archive Help Desk at http://masthelp.stsci.edu.

NASA High-End Computing Program

NASA's High-End Computing (HEC) Program maintains a comprehensive set of resources and services for the agency's four Mission Directorates, the NASA Engineering and Safety Center, external collaborators, and the nation. By closely partnering with each Mission Directorate, the HEC Program addresses their specific resource requirements and user needs. Mission support includes ensuring reliable remote access for a user community spread broadly across NASA centers and partner organizations nationwide.

Successful HST proposers will be eligible to apply for NASA High-End Computing Time. More information on NASA HEC Program can be found on https://www.hec.nasa.gov.

Duplication Checking

The HST Data Archive provides access to several tools that allow you to check whether planned observations duplicate any previously executed or accepted HST observations. See Data Rights and Duplication Policies for details.

STScI Help Desk

If this Call for Proposals and the materials referenced above do not answer your questions, or if you have trouble accessing or printing Web Documents, contact the STScI Help Desk at http://hsthelp.stsci.edu.

Next: HST Proposal Submission Policies