VOResource v0.8.2

[Anita Richards]

On Fri, 26 Sep 2003, martin hill wrote:

> I shall take this opportunity to raise my own pet peeve: UCDs are not nearly
> enough for describing data properly, so that we can compare and combine data
> across different datacenters.
>
> But the registry does need one (or several) ways of describing data
> using a common 'dictionary' of some sort, and UCDs are the best we've
> got right now!  It may be that not every column needs to be assigned a
> UCD (? what do people think? ) but the ones that astronomers are likely
> to query on (the WHERE part of an SQL clause) will need them.

Yes indeed...

As I understand it UCDs were evolved to aid catalogue _selection_ (before
services were available to manipulate much of the data inside catalogues)
and thus they are very well suited to registries. For example there is a
UCD for 'time' but it does not tell you if it is the start or stop time.
This is fine for the Registry to select catalogues which might be used to
plot a time series for an object.  Do we need separate UCDs for start and
stop times etc? As Martin suggests, that should be decided by looking at
existing science problems to see what would be useful and what is a
priority.  But isn't that more a VOQL issue than a registry issue?

cheers
a

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Dr. Anita M. S. Richards, AVO Astronomer
MERLIN/VLBI National Facility, University of Manchester,
Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL, U.K.
tel +44 (0)1477 572683 (direct); 571321 (switchboard); 571618 (fax).