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).

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 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

11. FITS Keywords: Common
FITS 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

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

17. Standardising Catalogues
Standardising IC S!
A NT
S EM
Naming
Column relationships (errors, bounds, notes…)
Dates & Units

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