ESO Images in a Universal Context

Astronomical metadata to provide better access to space images

9 March 2012

The European Southern Observatory has launched an initiative to attach extra information about context (metadata) to the images in its huge collection. The Astronomy Visualization Metadata standard that is now implemented has been developed in collaboration with many other major observatories, including partners from NASA, ESA, the California Academy of Sciences and the University of Arizona.

It is now easier than ever to learn more about the fantastic imagery of the Universe, including the archives of ESO. The Astronomy Visualization Metadata (AVM) standard was created to make access to astronomical images easier by collecting extra information in a standard way [1]. This extra information — known as metadata — includes details similar to those included with every digital snapshot picture coming from cameras today — who took the picture, when was it taken, where in the sky was the camera pointed and so on. It is, however, specifically designed for public-friendly astronomical images [2], making it much easier to find an image and much easier to put it into context. ESO has been helping to develop this tool and has been working on implementing it for all its astronomical images, culminating in its launch today.

Tagging our images with metadata means we can now classify astronomical images using one common universal ‘language’, making them more easily accessible to all,” explains Lars Holm Nielsen, Advanced Projects Coordinator at ESO, who led the efforts to implement the standard at ESO.

AVM tags, some of which are based on research-based standards used by scientists, have been specifically tailored to address the needs and interests of the general public and outreach community. For example coordinate tags (World Coordinate System or WCS tags) can be used to describe the position, orientation, and scale of an image, so that images can be easily used in virtual atlases of the sky and other such applications where coordinates are essential. Images now have links that take the visitor to Microsoft’s WorldWide Telescope. Or, for instance, all images taken with the MPG/ESO 2.2-metre Telescope can be displayed with one click. Also images of this telescope are available in one swift overview. Or all press releases with results from the Very Large Telescope are available in one list.

The ESO image gallery has AVM tagging running "under the hood" such that most of the information you see on the webpage is also embedded in the highest quality versions of the images. This kind of integration allows all of the information to be carried along and used by other applications.

Many applications already make use of these metadata. The NASA-led AstroPix database of astronomical images, an outreach project to which ESO contributes, already makes use of the AVM tags. AstroPix, which is currently in a beta version, offers access to the collected image libraries of a many of the leading astronomical observatories under a single unified interface. These include the Spitzer Space Telescope, the Chandra X-ray Observatory, the NASA/ESA Hubble Space Telescope, Galex, WISE and ESO. The tags are used to characterise the object types, captions, the facilities that took the images, the position in the sky and much more.

ESO has one of the biggest and best collections of astronomical images and now they have AVM tags they can be immediately searched and viewed in a very natural way, with AstroPix” adds Robert Hurt, leader of the AVM project as well as AstroPix. “It’s a big step forward.

Other applications and organisations using the AVM standard, which will now benefit from the newly tagged ESO images, include Microsoft’s WorldWide Telescope, Stellarium and Google Sky. And planetarium system producers such as Evans & Sutherland, Skyskan, and Uniview/SCISS already have AVM support, or will have, in their software.

This is a significant achievement for everyone involved in astronomy outreach. The wide response from our partners also means we will be able to better reach out to the public and share the incredible images coming from ESO’s many operating telescopes. We are grateful to everyone involved in this effort", [3] adds Lars Lindberg Christensen, Head of ESO Outreach and one of the initiators of the project.


[1] Metadata — additional information about data — describes the contents and context of data files using tags that can be used to classify files. It is used to describe digital data such as images using standards specially-tailored to the needs of a particular field.

[2] AVM, developed in the framework of Virtual Astronomy Multimedia Project (VAMP), is also relevant for artist‘s concepts and diagrams, simulations, and photography, and is only the first step in a future effort to encompass all multimedia products related to astronomy, including videos, podcasts, etc. VAMP is a collaborative project between individuals representing Spitzer Science Center, ESA/Hubble, California Academy of Sciences, IPAC/IRSA, and the University of Arizona. Key personnel at major observatories and end-application development organisations have endorsed the project and are committed to seeing success.

[3] ESO would like to thank the people without whose support this could not have been possible. They include Lars Holm Nielsen, Robert Hurt, Adrienne Gauthier, Amit Kapadia, Sarah Roberts and many others. Lars Holm Nielsen, who concludes a distinguished career at ESO with this release, is a specialist in development of information systems and software for cutting-edge science communication with a life long passion for astronomy. He has been working for the ESO-Hubble outreach group since 2002 and has been responsible for managing the implementation of advanced projects as well as the ESO’s outreach web infrastructure. In this capacity, he has been instrumental in developing the AVM system.

More Information

The year 2012 marks the 50th anniversary of the founding of the European Southern Observatory (ESO). ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive astronomical observatory. It is supported by 15 countries: Austria, Belgium, Brazil, Czechia, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 40-metre-class European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.



Lars Holm Nielsen
ESO, Garching, Germany
Cell: +49-151 22 652 416

Lars Lindberg Christensen
Head, ESO education and Public Outreach Department
Garching, Germany
Tel: +49-89-3200-6761
Cell: +49-173-3872-621

Robert Hurt
Spitzer Science Center
Tel: +1-626-395-1825

About the Announcement



Screenshot of an ESO image of the Orion Nebula shown in Microsoft’s WWT
Screenshot of an ESO image of the Orion Nebula shown in Microsoft’s WWT