Re: New UCDs for VOEvent please

From: Frederic V. \ <Hessman-at-Astro.physik.Uni-Goettingen.DE>
Date: Wed, 27 Apr 2005 13:34:54 +0200

> "how do you envision using these new UODs (Unified Object-type
> Descriptor)?" By that, I mean, in which part of the metadata would you
> like to insert theses descriptors?

To explain where I'm coming from, let's look at VOEvent and RTML:

• the VOEvent now has a <Classification type="(name)"> element, where (name) can be something like "supernova" or "gamma-ray burst".
• RTML has a TargetType used by a <Classification>(name)</Classification> element. Sound pretty similar? Yes, VOEvent could adopt RTML's element or vice versa, but what do the Virtual Repository people do? Is it really the job of VOEvent to suggest how all the VO colleagues are supposed to classify objects when they get around to needing such, especially when others start needed descriptions of objects and processes which will never produce an event?

I admit I'm a newcomer with no (as yet) official function, but I can't imagine the VO getting much farther without being able to teach the software how to describe what is is we're actually studying beyond saying that the number in a table is supposed to mean (admittedly an important first step).

> An object type may not be unique... How do we handle those cases?
> (after
> all, these are flags/labels to make our life easier. If the core of a
> galaxy is an AGN, what does the descriptor look like?
> UCDs of physical quantities are much easier to handle in that sense!
> (as
> noted below regarding the unicity of a UCD).

Why the need for a final description? From a VOEvent perspective, something should gradually shift from one description to another, e.g.

        process.burst;em.gamma -> process.burst;em.vis -> galaxies;stars.supernova
or - something which is bound to happen eventually (since it already has) -

        galaxies.Seyfert;galaxies.nucleus;em.X-ray -> stars.variable.cataclysmic.polar
  This capability for being able to descibe what people/computers think is happening has quite practical consequences when it comes to things like follow-up observations: some won't be interested in Seyferts, others in polars, and the Chandra ToO may insist that it be one or the other.

> How deep do we want to describe an object? Say that the same AGN has
> exhibited variations in HBeta flux (ok, kick for the incorrectness :-)
> :-)
> Do we want to describe such variability? For some people/applications
> it
> will be important, for others not.

Deep enough to be useful, shallow enough to be manageable.

Rick

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Dr. Frederic V. Hessman      Hessman-at-Astro.physik.Uni-Goettingen.DE
Universitaets-Sternwarte     Tel.  +49-551-39-5052
Geismarlandstr. 11                Fax +49-551-39-5043
37083 Goettingen                 http://www.uni-sw.gwdg.de/~hessman
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Received on 2005-04-27Z11:33:20