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With the arrival of MegaPrime, the new prime focus of the Canada France Hawaii 3.6-m telescope, equipped with MegaCam, a 340 Mpixel CCD mosaic offering a 1deg x 1deg field of view, started a new era of wide field astronomy at CFHT. Canada and France decided to join in a large program, the CFHT Legacy Survey (CFHTLS) aimed to contribute to three main scientific questions, while making sure that the data collected would serve a much broader community, thanks to a carefully chosen observing strategy. With a PI-less structure, data made available to any member of the French and Canadian communities, on-site real-time processing as well as elaborate post-processing also made available to all in France and Canada, the CFHTLS is both challenging and exciting. After a few months of pre-survey observations while MegaPrime was commissioned, the CFHTLS is now in operation since the end of August. The talk will present MegaPrime/MegaCam, describe the CFHTLS philosophy, its main scientific goals, and the many associate tools CFHT had to develop to support this very large program (~500 nights over 5 years).
In this review, the current status and expected evolution of data storage technologies in the next few years will be considered, in the light of the expected needs of constantly growing astronomical data volumes. Questions such as 'should we abandon tapes?' and 'why don't we just transfer all data over the net?', or 'Why do we give data out in the first place? The VO will provide results!' will be discussed.
The answers to the above questions have led to the definition of a new data distribution policy for the ESO/ST-ECF archive. This policy will affect both ESO program principal investigators as well as general archive users.
Data Models exist in people's heads. Data modelling consists of making these explicit on paper, so that (a) we can discover if there is more than one important model, and (b) we can develop using the model which has the best impedance match with the community being targeted. Thus modelling is not just about communications -- about bits (or angle brackets!) on the wire -- but is a software quality and usability issue.
We contend that there is in fact more than one model relevant to the VO, and that while the VOTable model is an excellent and valuable fit to the archivists' model of data, it may be a poor match for many users or (which is much the same thing) for the software written to service the sort of end-user astronomical applications which the VO targets.
Modelling work in other areas shows the importance of abstraction in the concrete goal of freeing software design from the particulars of any single implementation. This is extremely important for the VO because it allows us, and the software we write, to deal with the essentials of the data rather than the superficial aspects of a particular format such as XML or FITS. We discuss the work that we and others have been doing within this context; with this in mind, we will also review some of the various modelling languages available, such as XSchemas, UML, OMG MDA, HUTN, RDF, and Topic Maps.
Until recently, many astronomers regarded reducing radio astronomy data as an unnatural art. Yet pipelines and other user-friendly tools are now common. Most astronomers make some use of radio data such as in identifying galaxy types from the spectral energy distribution or probing obscured star-forming regions; and VOs use such problems as science drivers. The multitude of possible fields, resolutions, time-series and so on, which can be extracted from a single interferometry dataset, are at last becoming accessible, albeit usually via the observatories' individual web sites. The new generation of interferometers (ALMA, e-MERLIN, eVLA) will have easy data access designed into their archives. The next step for VOs and data providers is to provide interfaces so that data can be extracted from any registered archive without forcing the user to visit many sites.
Some current projects will be described, including: AstroGrid access to MERLIN archive data held at JBO; Expanding the capabilities of the European VLBI archive; Establishinging links and collating information from observatories world-wide alongside developing an interferometry data model for the IVOA.
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