VO Course 05: VOTable, VO Protocols, and UCDs

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Description of the VOTable data format, VO semantic tools (UCDs, UTypes), and VO protocols. Part of the virtual observatory course by Juan de Dios Santander Vela, as imparted for the MTAF (Métodos y Técnicas Avanzadas en Física, Advanced Methods and Techniques in Physics) Master at the University of Granada (UGR).

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VO Course 05: VOTable, VO Protocols, and UCDs

  1. 1. The VOTable, VO Protocols,and UCDsJuan de Dios Santander Vela (IAA-CSIC)
  2. 2. OverviewVOTable, the VO table formatUCDs, UTypes, & column semanticsSimple DAL protocols Simple ConeSearch Simple Image Access Simple Spectral Access
  3. 3. VOTable
  4. 4. VOTableXML-based metadata (and sometimes, data)formatAllows for things which cannot be done with FITS Semantic specification Hierachical resource nesting Linking (internal and to outside data)
  5. 5. VOTable StructureVOTABLE DESCRIPTION 0..1 DEFINITIONS 0..1 COOSYS 0.. PARAM INFO RESOURCE 0.. @ ID @ version restricts: xs:NMTOKEN
  6. 6. VOTable: COOSYSCOOSYS extends: xs:string @ ID ID restricts: xs:NCName type: ID from: XMLSchema.xsd @ equinox astroYear restricts: xs:token type: astroYear @ epoch astroYear restricts: xs:token type: astroYear @ system restricts: xs:NMTOKEN string restricts: xs:anySimpleType whiteSpace : preserve base: string from: XMLSchema.xsd
  7. 7. VOTable: RESOURCE RESOURCE DESCRIPTION 0..1 INFO 0.. COOSYS PARAM LINK 0.. TABLE 0.. RESOURCE 0.. ##other 0.. @ name @ ID @ utype @ type restricts: xs:NMTOKEN @ ##other
  8. 8. VOTable: TABLE TABLE DESCRIPTION 0..1 FIELD 0.. PARAM GROUP LINK 0.. DATA 0..1 @ ID @ name @ ref @ ucd @ utype @ nrows
  9. 9. VOTable: DATADATA TABLEDATA BINARY BINARY STREAM ref: BINARY FITS FITS STREAM @ extnum ref: FITS
  10. 10. VOTable: TABLEDATATABLEDATA TR TR TD 0.. 1.. ref: TR
  11. 11. VOTable: STREAMSTREAM extends: xs:string @ type restricts: xs:NMTOKEN locator other NMTOKEN restricts: xs:token base: NMTOKEN from: XMLSchema.xsd @ href @ actuate restricts: xs:NMTOKEN onLoad onRequest other none NMTOKEN restricts: xs:token base: NMTOKEN from: XMLSchema.xsd @ encoding encodingType restricts: xs:NMTOKEN gzip base64 dynamic none NMTOKEN restricts: xs:token base: NMTOKEN from: XMLSchema.xsd type: encodingType @ expires dateTime type: dateTime from: XMLSchema.xsd @ rights token restricts: xs:normalizedString type: token from: XMLSchema.xsd string base: string from: XMLSchema.xsd
  12. 12. Unified Content DescriptorUnified Content Descriptor (UCD) Extended unit Provides broad-range semantics for table columns, and class equivalence Mandatory attribute (@ucd) for VOTable FIELDs
  13. 13. UCD1+ Tree arith (arithmetics) em (electromagnetic spectrum) instr (instrument) meta (metadata) obs (observation) phot (photometry) phys (physics) pos (positional data) spect (spectral data) src (source) stat (statistics) time
  14. 14. UTypesUTypes are tools for direct mapping of columnsinto datamodels Allows for VOTable serialisation or complex data modelsAdditional, optional FIELD attribute (@utype)We will return to them when we talk about datamodels
  15. 15. VO Access ProtocolsAccess protocols == DAL protocolsSimple protocols Simple to query Complex to build, different protocol per data product type Simple ConeSearch, Simple Image Access, Simple Spectral Access Common data model: CharDM
  16. 16. ConeSearch endPointURL? RA=rightAscension& DEC=declination& mandatory SR=searchRadius& VERB=verbosity optional : ERIC IED GEN NTIF RC H IS E SEA UST B E ID C ONE M DS FIEL TA BLE
  17. 17. Simple Image Access endPointURL? mandatory POS=RA,DEC& SIZE=searchRadius& FORMAT=formatType& INTERSECT=intersectionMechanism& NAXIS=axisSizeVector& CFRAME=coordFrame& EQUINOX=equinoxSpec& CRPIX=refPixCoordVector& CRVAL=refPixValueVector& optional CDELT=pixScaleVector& ROTANG=rotationAngle& PROJ=projectionKind& VERB=verbosity
  18. 18. Simple Spectra AccessendPointURL?POS=ra,dec& APERTURE=apertAngle&SIZE=searchRadius& TIMERES=timeResol&BAND=freqRange& SNR=signal2noise&TIME=timeRange& REDSHIFT=redShiftRange&FORMAT=formatType& VARAMPL=amplitudeVariability&SPECRP=specResol& TARGETNAME=targetName&SPATRES=spatialResol& TARGETCLASS=targetClass&PUBDID=pubID& FLUXCALIB=fluxCalibKind&CREATORDID=creatorID& WAVECALIB=waveCalibKindCOLLECTION=collectionID&TOP=topNumResults&MAXREC=maxRecords& mandatoryMTIME=modificationTime& recommendedCOMPRESS=compressionFlag& optionalRUNID=jobRunID&
  19. 19. VO Access ProtocolsSxA Protocols simple to query But they need a lot of client-side processing for filteringTable Access Protocol REST: REpresentational State Transfer Direct access to tables Complex REST interaction
  20. 20. References & LinksVOTable format Simple ConeSearch UCDs Simple Image Access UCD1+ list Simple Spectral Access UTypes Table Access Protocol

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