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MAST Data Use Policy

Most data hosted at MAST are in the public domain (see: open data), and therefore do not have restrictions on use. There are, however, expectations (or in some cases, requirements) that researchers acknowledge the originating mission and (usually) STScI in all scholarly publications. See MAST Data Attributions for details.

The subset of data for which restrictions do apply are described in the following subsections.

Exclusive Access Data

Access to science data from most active missions is often limited to the Program Investigator Team during a period of exclusive access immediately following the observations. The duration of the exclusive access period ranges from a few months to as much as a year, depending upon the mission, the program category, and other factors. Some other data, such as those obtained during facility commissioning, or those that are found to duplicate concurrent observations by a Guaranteed Time Observer (GTO), may also be embargoed for a period of time. Data falling under exclusive access can be discovered via MAST public interfaces, but may not be retrieved except by authorized and authenticated persons. Following the expiration of the applicable exclusive access period, science data become available for public use without restriction.

Principal Investigators may request modifications (i.e., extensions, reductions, and/or restrictions) to the exclusive access period for some or all observations in their observing programs. Please make these requests via the Archive help desk: The Help Desk staff will forward all requests to the authorizing officials. All requests must be approved by STScI before being enacted.

Licensed Data

Some data products, such as high-level science products (HLSPs) which are created by the community and are made available through MAST, are covered under a Creative Commons Attribution license (CC BY 4.0). These products are available to the community for their use without restriction, provided that the product providers (i.e., the creators and MAST) are acknowledged in published works. If a user obtains such data from MAST and subsequently provides the data to a third party, the terms of the CC BY 4.0 license convey with the data.

Copyrighted Data

Certain data collections available through MAST are covered by copyright, and use of these data is restricted. The following collections are the product of a multi-institution collaboration, and are copyrighted:

  • Digitized Sky Survey (see DSS Copyright Holders, below)
  • Guide Star Catalogs (derived from the DSS images)

Scientists and educators conducting research, teaching (including textbooks), or other non-profit activities may use data from the copyrighted collections freely and without restriction, other than that users are requested to acknowledge the source of the data in any publications resulting from that use.

Commercial, for-profit use of the copyrighted collections is prohibited without written permission from the copyright holder(s). Contact for details.

DSS Copyright Holders

The DSS datarights are held by the following institutions depending on the survey plate material used.

Southern Hemisphere Surveys observed prior to 1993

Southern Hemisphere Surveys were made with the UK Schmidt Telescope at the Anglo-Australian Observatory. Plates from these surveys have been digitized and compressed by the STScI. The digitized images are copyright (c) 1976-1993, jointly by the UK SERC/PPARC (formerly Science and Engineering Research Council/Particle Physics and Astronomy Research Council, and currently the Science and Technology Facilities Council), and are distributed herein by agreement. All Rights Reserved. Represented by the Wide Field Astronomy Unit at the Royal Observatory Edinburgh (ROE); Contact

Southern Hemisphere Surveys observed since 1993

The "Second Epoch Survey" of the southern sky was made by the Anglo-Australian Observatory (AAO) with the UK Schmidt Telescope. Plates from this survey have been digitized and compressed by the STScI. The digitized images are copyright (c) 1993-2004 by the Anglo-Australian Observatory Board, and are distributed herein by agreement. All Rights Reserved; Contact

POSS-II Northern Hemisphere Surveys

The compressed files of the "Palomar Observatory - Space Telescope Science Institute Digital Sky Survey" of the northern sky, based on scans of the Second Palomar Sky Survey are copyright (c) 1993-2003 by the California Institute of Technology and are distributed herein by agreement. All Rights Reserved; Contact

POSS-I/Quick-V Northern Hemisphere Surveys

All material not subject to one of the above copyright provisions is copyright (c) 1984-2004 by the Association of Universities for Research in Astronomy, Inc. All Rights Reserved; Contact

Color DSS Images

For use of color DSS images not covered by above use policy, contact