f. genova, vo as a data grid, 2003/06/301 interoperability of astronomy data bases françoise...
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F. Genova, VO as a Data Grid, 2003/06/30 1
Interoperability of astronomy data bases
Françoise Genova, CDS
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Astronomy
• A small discipline
• Few commercial constraints
• A long term partnership to define exchange standards and links
FITS: early data exchange format
on-line information in astronomy:
from observations to results
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An early example of interoprerability: Name resolver
Object name >> position
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Evolving world - Web Services - Very Large Surveys
Simbad Name Resolver>> Sesame Web Service
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Web Services as building blocks
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The astronomy bibliographic network
Links between
– electronic journals– the ADS bibliographic database– on-line services (SIMBAD, NED)– … archival data/published results
bibcode e.g. 1999A&A...351.1003G
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References in anon-line article
links to ADS
quality check
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ADS
- Abstracts- Scanned articles- Links to original on-line paper- Links to other, distributed information e.g. original observations- Also-read articles
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ADS
From bibliographyTo the originalobservations
Search an author’s publications
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HST archiveFrom observationTo publication
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A&A on line
From publication to SIMBAD and more
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SimbadInformationAbout the object
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Links To high energyobservations inHEASARC,To Catalogues
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Links from object names in journals: an early example: IBVS
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Links to images and data
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GCVS
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Lessons learnt• De facto standard
SIMBAD/NED, ADS, journals, archives
• Cooperation between all the actors+ snowball effectJournals, ADS, data centres, archive centres
• The community is trained (everyday tools)• Easy-to-build link
but contents / validation are fundamentalthe role of experts remains fundamental for
building value-added services
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Data federationTabular data in astronomy
A common description for tabular data– Reference catalogues– Published tables– Surveys– Catalogues of observations in archives
ReadMephysical organization contents
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ReadMe
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Tables published in articles are usable data!
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Links to observational data (images, spectra, time series), often distributed in observatory archives
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An homogenized view of heterogeneous informationWith links to data
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Towards data integration
• XML
• VOTable > Roy’s talk
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HEARSARCBrowse
Astroresin action!
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With a touch of GLU
Générateur de Liens Uniformes
• Resource dictionary (shared, distributed, hierarchical name space, clone management…), knows the query syntax
• Resolver: symbolic name > URL• An early registry prototype with many of
the required functionalities (conversions, failure tests, …)
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Observations from European archivesInclusive: NASA missions HST, Chandra, surveys, …
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Glu Tag Resolver
Symbolic name >> URL
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Data mining: the Uniform Content Descriptors
• A set of UCDs has been first developed in the frame of the ESO/CDS Data Mining project to describe VizieR catalogue columns (100.000 columns, 1.300 UCDs)
• Name for concept• Assigned semi-automatically using column label,
description and unit• Used e.g. to check the coherence of information in
tables
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UCD browser
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UCD+units: conversion, selection
Select catalogues & target
Join on UCDs :
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Colour excess characterizes carbon stars
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http://cdsweb.u-strasbg.fr/UCD/
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Extension of UCDs
• SDSS: 1.500 columns– Manual verification needed– Very few additional UCDs
• On-going:– UCDs for VOX– UCDs for IDHA data modelAdd ‘Metadata’ branch … FITS keywords are often not accurate
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Validation, maintenance
• A new structure
• Prune the existing UCD tree
• UCD steering group– Proposal in October 2003– UCD V1.0– Evolution mechanism
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The future
• Other knowledge basis– List of object names– Journal keywords– Thesaurus (built by librarians)…
Astronomy described with different points of view
Converging towards an ontology of astronomy??