MTAF VO Course 02: Astronomy & Standards

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).

Transcript

1. Astronomy & Standards
   Interoperability of astronomical data
   Juan de Dios Santander Vela (IAA-CSIC)
   

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2. Overview
   Astrophysical records
   Sharing astrophysical data
   Interoperability standards
   

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3. Astrophysical Records
   

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4. Astrophysical records
   Aurignacian Lunar Calendar / diagram, drawing after
   Marshack, A. 1970; Notation dans les Gravures du
   Paléolithique Supérieur, Bordeaux, Delmas / Don’s Maps
   

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5. Astrophysical records
   In astrophysics, we record the EM radiation from
   distant objects, in order to:
   understand the processes that generated the
   EM radiation
   understand the processes that affect the
   received EM radiation
   

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6. Many different records
   Astrophysical records are different by means of
   their
   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
   

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7. Many different records
   Many, many things can change
   Coordinate system, physical measurement,
   physical support…
   And that’s just the observation generation!
   

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8. Many different records
   Most of those records can be represented as
   multi-dimensional arrays
   Need to specify
   Units
   Sampling
   Physical meaning
   

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9. FITS: the Flexible Image
   Transport System
   Header + Table data
   Special case: Image data
   Header: Keyword-value pairs
   2-level hierarchies (Main HDU + Extensions)
   NASA Standard + IAU Recommendation
   

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10. FITS Keywords: Basic
    FITS
    SIMPLE
    END
    DATE
    BITPIX
    XTENSION
    EXTNAME
    EXTLEVEL
    EXTVER
    EXTEND
    COMMENT
    HISTORY
    BLOCKED
    Provenance
    ORIGIN
    AUTHOR
    OBSERVER
    DATE-OBS
    TELESCOP
    INSTRUME
    OBJECT
    REFERENC
    Coordinates
    EPOCH
    EQUINOX
    NAXIS
    NAXISn
    CTYPEn
    CRVALn
    CDELTn
    CRPIXn
    CROTAn
    Tables &
    Images
    BLANK
    DATAMIN
    DATAMAX
    TFIELDS
    BSCALE
    BUNIT
    BZERO
    TFORMn
    TNULLn
    TBCOLn
    THEAP
    TUNITn
    TDIMn
    TZEROn
    TDISPn
    TSCALn
    TTYPEn
    GROUPS
    GCOUNT
    PCOUNT
    PTYPEn
    PSCALn
    PZEROn
    

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11. FITS Keywords: Common
    FITS
    TITLE
    FILENAME
    FILETYPE
    ROOTNAME
    PROGRAM
    CREATOR
    CONFIGUR
    NEXTEND
    HDUNAME
    HDUVER
    HDULEVEL
    TLMINn
    TLMAXn
    TDMINn
    TDMAXn
    TDBINn
    TSORTKEY
    PROGRAM
    CREATOR
    CONFIGUR
    HDUCLASS
    HDUDOC
    HDUVERS
    HDUCLASn
    CHECKSUM
    DATASUM
    CHECKVER
    Groupings
    GRPNAME
    GRPIDn
    GRPLCn
    Provenance
    OBS_ID
    OBS_MODE
    DATAMODE
    APERTURE
    DETNAM
    FILTER
    FILTERn
    GRATING
    GRATINGn
    SATURATE
    Target
    SUNANGLE
    MOONANGL
    RA
    DEC
    RA_NOM
    DEC_NOM
    RA_OBJ
    DEC_OBJ
    RA_PNT
    DEC_PNT
    PA_PNT
    RA_SCX
    DEC_SCX
    RA_SCY
    DEC_SXY
    RA_SCZ
    DEC_SCZ
    ORIENTAT
    AIRMASS
    LATITUDE
    OBJNAME
    Time & Date
    TIME-OBS
    TIME-END
    DATE-END
    EXPOSURE
    EXPTIME
    TELAPSE
    ELAPTIME
    ONTIME
    LIVETIME
    Conventions
    HIERARCH
    INHERIT
    CONTINUE
    

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12. Curse of Flexibility
    FITS 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
    

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13. 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.
    

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14. Astronomical Catalogues
    Collections of astronomical object properties
    Typically, the result of many observations, or
    exhaustive treatment of all object in a observation
    Main index types
    Spatial
    Temporal
    Object template
    

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15. Astronomical Catalogues
    Explosion of catalogues since early ‘90s, thanks to
    Digitised astronomy
    Internet (FTP ➡ WWW)
    Journal tables
    

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16. Astronomical Catalogues
    Astrometry
    Photometry (no
    Radio)
    Spectroscopy
    Cross-Identifications
    Combined Data
    Miscellany
    Non-stellar Objects
    Radio Catalogues
    High-Energy
    Catalogues
    Journal Catalogues
    

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17. Standardising Catalogues
    Standardising
    Naming
    Column relationships (errors, bounds, notes…)
    Dates & Units
    SEMANTICS!
    

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18. References & Links
    FITS Standard Document
    FITS World Coordinate System
    FITS Dictionaries
    Standard for Documentation of Astronomical
    Catalogues
    UCD List
    

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