Data Access Policy for ESO Data held in the ESO Science Archive Facility

Published on 11 May 2022. Applicable from that date onward.

The European Southern Observatory (ESO) Science Archive Facility (SAF) has been operational at ESO headquarters in Munich since 1991. It contains data from ESO telescopes at La Silla Paranal Observatory, including the APEX submillimeter telescope on Llano de Chajnantor. All raw data from the La Silla Paranal Observatory are stored together with the corresponding calibrations, as well as selected products both contributed by the community or generated at ESO. In addition, it contains the UKIDSS/WFCAM data obtained at the UK Infrared Telescope facility in Hawaii, as well as the science processed data from the ESO large programmes.

The Principal Investigators (PIs) of successful proposals for time on ESO telescopes, and their delegates, have exclusive access to their scientific data for the duration of a proprietary period, after which it is accessible to all users from the international community. Processed data distributed via the SAF retain the same proprietary protections as the raw data they were derived from. The length of the proprietary period is set by the Director General and communicated in the Phase 1 Call for Proposals. The proprietary period starts when the raw data is made available for download from the ESO SAF to the PI, or their delegates. It is typically of one year and may depend on the observing programme type (e.g. Public Survey raw data is not covered by proprietary protection).

The information contained in the headers of all the data files in the ESO SAF is in normal circumstances immediately and publicly available. The abstracts of successful proposals are made public at the time the proprietary period expires. All calibration data are public immediately after the observations.

Exceptions to the above rules, such as the extension of the proprietary period or restrictions to the access to header information, may be granted in special cases. The corresponding requests have to be justified in detail and submitted to the Director General of ESO for approval. Deviations from the general policies may also occur for Guaranteed Time Observations (GTO). Please check the dedicated information at the GTO policy page.

All data in the ESO archive retain ESO’s copyright, and are distributed according to the terms of the Creative Commons Attribution 4.0 International license (CC BY 4.0).

ESO subscribes to the FAIR Guiding Principles for scientific data management and stewardship (see

When downloading data from the SAF, all users are requested to limit to maximum five concurrent downloads.

Requirements for third parties distributing ESO data

ESO data files (both raw and processed data) may be distributed by third parties, and disseminated via other services, according to the terms of the Creative Commons Attribution 4.0 International license. Credit to the ESO provenance of the data must be acknowledged, and the file headers preserved.

In case of scientific use of the ESO data by users that access ESO data via third party archival services, the users should follow the same acknowledgement policies as for the ESO SAF, as described below.

Acknowledgement policies

If the access to the ESO SAF services was helpful for the users’ science work, the following acknowledgement is required:

This research has made use of the services of the ESO Science Archive Facility.

All users of the ESO SAF are required to acknowledge the source of the data with an appropriate citation in their publications.

Publications making use of ESO raw data must include the following statement in a footnote or in the acknowledgement:

Based on observations collected at the European Southern Observatory under ESO programme(s) TP.C-NNNN(R)1 or PPP.AAAA.nnn2

Processed data downloaded from the ESO Archive are assigned a Digital Object Identifier (DOI). The list of the DOIs currently available can be found here. The following statement must be included in any publications making use of them:

Based on data obtained from the ESO Science Archive Facility with DOI(s) under

Publications making use of the ESO raw or processed data which have been assigned an archive request number (of the form XXXXXX) must include the following statement in a footnote or in the acknowledgement:

Based on data obtained from the ESO Science Archive Facility under request number <request_number>.

Publications making use of APEX observational data must include the following statement in a footnote or in the acknowledgement:

Based on data acquired with the Atacama Pathfinder Experiment (APEX) under programme(s) TP.C-NNNN(R)1 or PPP.AAAA.nnn2. APEX is a collaboration between the Max-Planck-Institut für Radioastronomie, the European Southern Observatory, and the Onsala Space Observatory.

For publications making use of ALMA observational data, please see the ALMA acknowledgement at

For scientific institutions distributing further ESO raw and/or processed data:

Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme(s) TP.C-NNNN(R)1 or PPP.AAAA.nnn2, and/or processed data created thereof.

(1) Please substitute the place-holder TP.C-NNNN(R) with the programme ID(s) of the data used, e.g., 094.A-1234(A).

(2) As of ESO period 105 (proposal deadline 26 September 2019, start of observations on 1 April 2020), but also including DDT programmes of period 104, the programme ID format changed to a new simplified structure PPP.AAAA for Programme ID and PPP.AAAA.nnn for run ID, where PPP is Period, and nnn is number of the run, and AAAA is a unique identifier composed of numbers and letters.

(3) Please substitute NNN with the correct number from the doi column in the table at

You will find the ESO Programme identifier in the FITS header of the observations (under keyword HIERARCH ESO OBS PROG ID for raw data and under keyword PROGIDn for processed data). The description of the programme ID syntax is provided in the ESO programme identification code page.