UCDS and DM

[posuna at iso.vilspa.esa.es]

Hi,

> I was slightly puzzled by comments at the interoperability workshop
> about data collections which do not have catalogues/tables.  Surely
> even a collection of FITS spectra or images or etc. must be accessed
> via a descriptive list? Although I suppose a data collection could
> consist of a single image (or etc.). In either case, though, is this
> is another example of where it would be useful to take UCDs from what
> might be a single description ("images taken at 0.05 arcsec resolution
> ...") of the whole data collection - and use them to form or augment a
> table to allow access to the data?


We do have quite complex data models for our data; you can see part of
the ISO model in the attached figures called iso_cdm_obss.gif and
iso_pdm_obss.gif which are part of our (database jargon) CDM (Conceptual
Data Model) and PDM (Physical Data Model) documents (where you can see
loads of very project-specific things).

The access to our data is not done through a descriptive list, but
through database queries. However, in the case that someone wants a
catalogue/table from our data, we can provide one. 

This is what we do with CDS: we provide them with the table they
store in Vizier and that can be used as the rest of catalogues there for
data mining (I'm not sure whether this is the word...I mean data
discovery, etc.). You can find this table at:

ftp://cdsarc.u-strasbg.fr/cats/B/iso/isolog.dat.gz

However, that is only a very specific view of our data which can,
otherwise, be accessed through other means, e.g., by SIAP or future
SSAP, etc., or in the case of a proper general Data Model, through a
proper VOQl to the Data Model (how we translate the future "Standard VO
data Model" to ours is another story...(unfortunately, only up to
us I'm afraid...)).



Cheers,
Pedro.







-- 

Pedro Osuna Alcalaya


SOFTWARE Development Group
XMM-Newton Science Archive				
e-mail: Pedro.Osuna at esa.int
Tel + 34 91 8131314  				

European Space Agency
VILLAFRANCA Satellites Tracking Station
P.O. Box 50727 
E-28080 Villafranca del Castillo
MADRID - SPAIN

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