1. www.g-vo.org The International Virtual Observatory Alliance (IVOA) interoperability in action

2. www.g-vo.org Babylonian confusion SDSS ROSAT 2MASS FIRST GAIA

3. www.g-vo.org ROSAT FIRST GAIA SDSS2MASS Esperanto

4. www.g-vo.org IVOA Members IVOA Members

5. www.g-vo.org IVOA Mission statement “facilitate the international coordination and collaboration necessary for the development and deployment of the tools, systems and organizational structures necessary to enable the international utilization of astronomical archives as an integrated and interoperating virtual observatory.“

6. www.g-vo.org Working and Interest Groups Working and Interest Groups WGs –Standards and Process: how the IVOA works –Resource registry: where to register and discover resources –Data Modeling: how to describe data sets –Semantics: how to understand one another –VOTable: standard format for tabular data sets –Data Access Layer: very simple data access services –VO Query Language: more sophisticated data access –Grid and web services: programmatic accessibility –Applications: stand alone, and together –VOEvent: astronomical telegrams in XML IGs –Theory: virtual observations for virtual universes –Open GridForum Astro-RG: VObs and virtual organisations –Data Curation and Preservation: how not to loose your data

7. www.g-vo.org Resource Registry http://www.ivoa.net/twiki/bin/view/IVOA/IvoaResReg XML schema: http://www.ivoa.net/Documents/WD/ReR/VOResource- 20060620.html http://www.ivoa.net/Documents/WD/ReR/VOResource- 20060620.html Implementations: –Searchable Registry at STScISearchable Registry at STScI –NCSA Publishing RegistryNCSA Publishing Registry –ESAVO Full RegistryESAVO Full Registry Client tools: –VOExplorer (AstroGrid)VOExplorer –Splat, SpecView, Aladin

8. www.g-vo.org Data Modeling http://www.ivoa.net/twiki/bin/view/IVOA/IvoaDataModel Describe some standard data products –Data –Metadata ! –XML serialisation In process: –Space-Time CoordinatesSpace-Time Coordinates –1D Spectrum (used in SSA)1D Spectrum –Characterisation of data setsCharacterisation

9. www.g-vo.org Semantics http://www.ivoa.net/twiki/bin/view/IVOA/IvoaSemantics Provide standard lists of terms To be used wherever different agents need to understand each other UCDs: names of propertiesUCDs Semantic Vocabularies: astronomical termsSemantic Vocabularies

10. www.g-vo.org VOTable http://www.ivoa.net/twiki/bin/view/IVOA/IvoaVOTable XML format for tabular data Column definitions included with data Binary streams and FITS included Understood by many client tools (see applications set) –TOPCAT –VOPlot –Aladin

11. www.g-vo.org VOTable example

12. www.g-vo.org Data Access Layer I http://www.ivoa.net/twiki/bin/view/IVOA/IvoaDAL Simple protocols for discovering and retrieving data sets Generally HTP-GET based: –Base url: http://www.g-vo.org/ssa?action=doQuery&archiveid=ssa.service.cdfs –Query parameters: POS=53.161,-27.832&SIZE=0.2&BAND=0/&TIME=,&FORMAT=ALL Returns list of spectra with access URL for retrieving them.

13. www.g-vo.org Data Access Layer II Examples form GAVO, for more usage examples see tool demosGAVO –Simple cone search (source catalogues)Simple cone search ROSAT source catalogues and photon event lists) –Simple Image AccessSimple Image Access ROSAT pointed observations and All-Sky Survey fields –Simple Spectral AccessSimple Spectral Access Chandra Deep Field South optical follow up

14. www.g-vo.org Interoperability Standard services, once registered, can be found by client tools …

15. www.g-vo.org Interoperability ….and executed together (too many ROSAT results to show all here!)

16. www.g-vo.org Interoperability … and shown together

17. www.g-vo.org VObs Query Language http://www.ivoa.net/twiki/bin/view/IVOA/IvoaVOQL Querying remote databases –Remote filtering: reduces data to be sent –Combination (even distributed!) ADQL –SQL based –Some extra astronomical features Databases online –SDSS SkyServer –Millennium database (see demo)

18. www.g-vo.org Grid and web services http://www.ivoa.net/twiki/bin/view/IVOA/IvoaGridAndWeb Serviceshttp://www.ivoa.net/twiki/bin/view/IVOA/IvoaGridAndWeb Services Web services can be made accessible to other applications –SOAP/WSDL –REST –Grid Needs agreements on –Security: Single-Sign-On –Distributed storage: VOSpace –Standardised components: Universal Worker Service But then: distributed workflows !

19. www.g-vo.org VOEvent http://www.ivoa.net/twiki/bin/view/IVOA/IvoaVOEvent XML format for messages about sudden events –Where ? –What ? –When ? Robotic telescopes might connect to this … Users can connect to stream and selectively filter

20. www.g-vo.org Applications http://www.ivoa.net/twiki/bin/view/IVOA/IvoaApplications See various targeted demos: –Aladin (applet) –TOPCAT (webstart)webstart –SpecView (webstart) –… Application interoperability: Plastic –Messaging standard –Tying TOPCAT to Aladin to Splat to …TOPCAT –all on your desktop

21. www.g-vo.org IG: Theory http://www.ivoa.net/twiki/bin/view/IVOA/IvoaTheory