UCDS and DM

[Patricio F. Ortiz]

On Tue, 21 Oct 2003, Anita Richards wrote:

> Please can I clarify a possible application, which may initially be done
> in an ad-hoc way until data models are fully harnessed:
>
> Supposing we are harvesting a catalogue which consists of radio flux
> densities measured at 22 GHz.  This is stated in the Abstract or ReadMe or
> maybe even the title, but there is no table in the data saying 'observing
> frequency'.  As I understand it, we could add a virtual column
> em.radio.12-25GHz, in which all the entries are the same.  Can this be
> done as a default, so that the data are recognised at their proper
> frequency?

Anita,

the way UCD1 would handle this is that the UCD associated to the flux
will reflect the region of the radio spectrum, eg,
PHOT_FLUX_RADIO_11-25GHz, therefore, your catalogue will be discovered
by the presence of that UCD without having to add a virtual column
describing the observed frequency range. This case was very common, and
not only in radio. There are hundreds of columns with "magnitude" as
explanation, and you find the waveband in either the readme or the
table title. UCDs are supposed to reflect the quantity as well as
possible, that's why even with UCD1 one can launch discovery queries of
this type and discover catalogues which have no indication of that part
of their content in other pieces of meta-data information.

Cheers,

Patricio

---
Patricio F. Ortiz			pfo at star.le.ac.uk
AstroGrid project
Department of Physics and Astronomy
University of Leicester			Tel: +44 (0)116 252 2015
LE1 7RH, UK