Online Information in Astronomy - From networking to a virtual observatory

Genova, Francoise Online Information in Astronomy - From networking to a virtual observatory., 2002 . In 1st Open Archives Forum Workshop, Pisa (Italy), May 2002. [Presentation]

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English abstract

Astronomy relies on long-term observations of variable phenomena, and conserving and reusing data is the key for major scientific objectives, such as the definition of objects and of their properties, or the study of variability and evolution, all this requiring statistical studies on large number of objects. Observations at different wavelengths, with different techniques, allow one to understand the physical phenomena at work in objects. In addition, astronomical observations rely more and more on large ground-based and space observatories, and on large surveys of the sky, and reusing their data for new scientific objectives is necessary to optimise the scientific return of these large projects. This is an old, but increasingly complex endeavour: information volume and complexity increase, and information is heterogeneous and distributed. Moreover, data must be properly documented to remain usable. A technical revolution has of course occurred in the last years in that domain, with the increased technical capacity to store and manage information, and the new possibilities offered by the WWW in terms of information distribution, of integration of data with documentation, and of navigation between on-line services. These useful and appealing tools are widely used, but one has to keep in mind that careful work on the service contents and functionalities remains mandatory, and that information validation remains critical. Moreover, services and links have to be maintained on the long term. The development of services for the usage of the scientific community puts new constraints on the Agencies, with competition between data conservation/diffusion and the implementation of new instruments or operational costs. The scientific community also has to put a sufficient priority on this activity, in projects, evaluation, and strategic plans, and to encourage motivated scientists and engineers to work on data conservation and diffusion. Projects have to make their data available, in a usable form, i.e. data has to be properly selected, organized and documented, and the "project memory" has to be kept. Astronomy has very rapidly taken advantage of the new technical possibilities, by developing on-line information services and information networking. It is a small discipline with few commercial constraints, which has helped to build long term partnership to define community standards, thus allowing the development of links and of generic tools to access data. The network of astronomical information goes from observations, distributed in observatory archives, to results published in electronic journals, with also disciplinary centres distributing data and information in a given domain, and Data Centers building value-added services and generic tools. For instance, the Centre de Données astronomiques de Strasbourg (CDS), created in 1972 with the mission of taking care of electronic data, of building expertise about the data, of implementing tools for science, and of playing an international role, now summarizes its charter as follows: "Collect, homogenize, preserve, distribute astronomical information, for the usage of the whole astronomy community". Astronomy has developed disciplinary standards and tools for interoperability: for instance, FITS is a widely used data format (images, spectra, tables), and data from any telescopes is kept in FITS format, thus allowing the usage of common tools to deal with it. Another example is the "bibcode" (a 19-character description of published references), first defined by database managers who had to exchange bibliographic information, then adopted and extended by the reference astronomical bibliographic database, ADS, then by the journals when they developed electronic versions, then by observatory archives when they wished to implement links with published papers using their observations. The successful networking of bibliographic information in astronomy demonstrates how a high level of interoperability can be built using de facto standards, with a bottom-up approach defined by a small group of practitioners (long before the advent of the Internet!) and "snowball effect" in the community. In this model, links are easy to build but the quality of contents and validation are fundamental and in thehands of specialists. To take into account the current development of general standards for bibliography, a gateway with bibcode will be developed, to preserve on one hand the human readability of the bibcode and the functionalities and networking of astronomy on-line resources, and on the other hand to permit links with other disciplines (e.g. a correspondence table between the bibcode and DOI). Another example of disciplinary standard is the description of tabular data, the "ReadMe", an ASCII file, which contains information about the physical organization of the data and about its scientific meaning. It is common to catalogues, tables published in journals, surveys, and catalogues of observations in archives. It allows also a check of the homogeneity of tabular data in journals before publication, which improves the quality of published information, in addition to the peer review. This also means that published tables are usable data, and not only figures printed on paper. In the recent years, an XML standard for astronomical tabular data has been developed (astrores), and the usage of XML is currently widely discussed and implemented in the context of the Virtual Observatory projects. The Virtual Observatory (VO) can be defined as "an enabling and coordinating entity to foster the development of tools, protocols, and collaborations necessary to realize the full scientific potential of astronomical databases in the coming decade" (NVO White Paper, June 2000). The VO has many components, going from network infrastructure or computer and data GRID, to tools and standards for data mining, or to statistical tools able to access very large, distributed data sets. Several RTD/Phase A projects have been accepted in 2001, the Astrophysical Virtual Observatory in Europe, the National Virtual Observatory in USA, AstroGrid in UK, ... The European project (PI: European Southern Observatory, partners: ESA-ECF, AstroGrid, CDS, Terapix, Jodrell Bank) has three work areas: Science use case and requirements, Interoperability deployment and demonstration, and Technology needs.CDS is responsible for the Interoperability Work Area, and a prototype using the CDS data federation and data integration tools is being developed, to give access to ground- and space-based, multi-wavelength, multi-technique archives. The prototype is made available to the community for scientific usage, in order to obtain science results and user feedback at an early stage of the project. Another objective is to establish a set of usable recommendations for helping archive managers to implement interoperability. CDS also leads the Interoperability Working Group set up by the OPTICON European Network, which aims at studying cost effective tools and standards for improving access and data exchange to/from data archives and information services. The VO projects are coordinating their activities at the international level, and the first common milestone has been the definition of an XML standard for tabular data, VOTable (V1.0 was released on April 15, 2002).

Item type:	Presentation
Keywords:	Virtual Observatory (VO), Open Archive Iniziative, Astronomy
Subjects:	L. Information technology and library technology
Depositing user:	Andrea Marchitelli
Date deposited:	09 Jun 2005
Last modified:	02 Oct 2014 11:58
URI:	http://hdl.handle.net/10760/4689

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