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)
2. Overview Astrophysical records Sharing astrophysical data Interoperability standards
3. Astrophysical Records
4. Astrophysical records Aurignacian Lunar Calendar / diagram, drawing after Marshack, A. 1970; Notation dans les Gravures du Paléolithique Supérieur, Bordeaux, Delmas / Don’s Maps
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
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
7. Many different records Many, many things can change Coordinate system, physical measurement, physical support… And that’s just the observation generation!
8. Many different records Most of those records can be represented as multi-dimensional arrays Need to specify Units Sampling Physical meaning
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
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
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
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
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.
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
15. Astronomical Catalogues Explosion of catalogues since early ‘90s, thanks to Digitised astronomy Internet (FTP ➡ WWW) Journal tables
16. Astronomical Catalogues Astrometry Photometry (no Radio) Spectroscopy Cross-Identifications Combined Data Miscellany Non-stellar Objects Radio Catalogues High-Energy Catalogues Journal Catalogues
17. Standardising Catalogues Standardising Naming Column relationships (errors, bounds, notes…) Dates & Units SEMANTICS!
18. References & Links FITS Standard Document FITS World Coordinate System FITS Dictionaries Standard for Documentation of Astronomical Catalogues UCD List