VO Course 02: Astronomy & Standards
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VO Course 02: Astronomy & Standards

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Overview of the virtual observatory course by Juan de Dios Santander Vela, and part of the MTAF (Métodos y Técnicas Avanzadas en Física, Advanced Methods and Techniques in Physics) Master at the ...

Overview of the virtual observatory course by Juan de Dios Santander Vela, and part of 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 02: Astronomy & Standards VO Course 02: Astronomy & Standards Presentation Transcript

  • Astronomy & StandardsInteroperability of astronomical dataJuan de Dios Santander Vela (IAA-CSIC)
  • OverviewAstrophysical recordsSharing astrophysical dataInteroperability standards
  • Astrophysical Records
  • Astrophysical records Aurignacian Lunar Calendar / diagram, drawing after Marshack, A. 1970; Notation dans les Gravures du Paléolithique Supérieur, Bordeaux, Delmas / Don’s Maps
  • Astrophysical recordsIn astrophysics, we record the EM radiation fromdistant objects, in order to: understand the processes that generated the EM radiation understand the processes that affect the received EM radiation
  • Many different recordsAstrophysical records are different by means oftheir EM/energy range (long vs. short-λ radio, IR, optical, UV, X-Ray, ɣ-Ray) Product type (images, time series, spectra, spectral cube, image cube, combinations…) Instrument setup
  • Many different recordsMany, many things can change Coordinate system, physical measurement, physical support… And that’s just the observation generation!
  • Many different recordsMost of those records can be represented asmulti-dimensional arrays Need to specify Units Sampling Physical meaning
  • FITS: the Flexible ImageTransport SystemHeader + Table data Special case: Image dataHeader: Keyword-value pairs 2-level hierarchies (Main HDU + Extensions)NASA Standard + IAU Recommendation
  • FITS Keywords: BasicFITS Provenance Coordinates BSCALE SIMPLE ORIGIN EPOCH BUNIT END AUTHOR EQUINOX BZERO DATE OBSERVER NAXIS TFORMn BITPIX DATE-OBS NAXISn TNULLn XTENSION TELESCOP CTYPEn TBCOLn EXTNAME INSTRUME CRVALn THEAP EXTLEVEL OBJECT CDELTn TUNITn EXTVER REFERENC CRPIXn TDIMn EXTEND CROTAn TZEROn COMMENT TDISPn HISTORY TSCALn TTYPEn BLOCKED Tables & GROUPS Images GCOUNT BLANK PCOUNT DATAMIN PTYPEn DATAMAX PSCALn TFIELDS PZEROn
  • FITS Keywords: CommonFITS HDUDOC GRATING ORIENTAT HDUVERS GRATINGn AIRMASS TITLE HDUCLASn SATURATE LATITUDE FILENAME OBJNAME FILETYPE CHECKSUM ROOTNAME DATASUM Target PROGRAM CHECKVER SUNANGLE Time & Date CREATOR MOONANGL TIME-OBS CONFIGUR RA TIME-END NEXTEND Groupings DEC DATE-END HDUNAME GRPNAME RA_NOM EXPOSURE HDUVER GRPIDn DEC_NOM EXPTIME HDULEVEL GRPLCn RA_OBJ TELAPSE TLMINn DEC_OBJ ELAPTIME TLMAXn RA_PNT ONTIME TDMINn Provenance DEC_PNT LIVETIME TDMAXn OBS_ID PA_PNT TDBINn OBS_MODE RA_SCX TSORTKEY DATAMODE DEC_SCX Conventions PROGRAM APERTURE RA_SCY HIERARCH CREATOR DETNAM DEC_SXY INHERIT CONFIGUR FILTER RA_SCZ CONTINUE HDUCLASS FILTERn DEC_SCZ
  • Curse of FlexibilityFITS can accommodate data from any instrument/telescope but the price is semantics can be very different from instrument to instrument initially solved through manuals for each instrument this doesn’t scale for multi-λ astronomy
  • Astronomical Catalogues Robert Grant: Catalogue of 6415 stars for the epoch 1870. Glasgow: James MacLehose & Sons, 1883. Pages 472-473, beginning of the catalogue. Sp Coll MacLehose f8.
  • Astronomical CataloguesCollections of astronomical object propertiesTypically, the result of many observations, orexhaustive treatment of all object in a observationMain index types Spatial Temporal Object template
  • Astronomical CataloguesExplosion of catalogues since early ‘90s, thanks to Digitised astronomy Internet (FTP ➡ WWW) Journal tables
  • Astronomical Catalogues Astrometry Miscellany Photometry (no Non-stellar Objects Radio) Radio Catalogues Spectroscopy High-Energy Cross-Identifications Catalogues Combined Data Journal Catalogues
  • Standardising CataloguesStandardising IC S! A NT S EM Naming Column relationships (errors, bounds, notes…) Dates & Units
  • References & LinksFITS Standard DocumentFITS World Coordinate SystemFITS DictionariesStandard for Documentation of AstronomicalCataloguesUCD List