SV: do we need it?

[Frederic V. Hessman]

 > It has been suggested that the need for the SV is obvious and  
pressing. Is
 > it? What for? Maybe people could reply to this with their own views.

> One of the original motivations for the SV came from DAL/DM: we  
> have a need to describe the type of astronomical object observed  
> (Target.Class), or search for data for a particular class of object  
> (TargetClass input parameter) and found that, while some partial  
> compilations of this type had been created within astronomy, there  
> was nothing comprehensive.
>
> As a starting point it would be good to have such a list so that  
> data publishers can assign a standard classification to an object  
> when an observation is published, rather than just make one up as  
> we do currently (this does not require infererence, just a good  
> well thought out and comprehensive classification system). Later,  
> once we have this, is will also be desirable to be able to map less  
> well-formed user inputs for astronomical object types to the SV in  
> a portal, so that we can use this for data discovery (this could  
> benefit from inference capabilities).
>
> I imagine VOEvent (at least) has a very similar problem.
We could continue to go through the formal products created by the  
IVOA or other groups (e.g. HTN) and see where standardized tokens  
would have been handy.

On a more fundamental level: if the goal of the VO is to permit  
automated or at least computer-assisted work in a form appropriate to  
aid a human astronomer, then the VO has to have a fundamental basis  
which labels things like human astronomers do.   If you want to ask  
something like "Show me all the IMAGES taken with an OPTICAL CAMERA  
on a 2.0m or bigger GROUND-BASED TELESCOPE through a JOHNSON I-BAND  
FILTER of the any BARRED SPIRAL GALAXIES in the sdss CATALOGUE so  
that I can probe the CUSPiness of the BULGE's light given the  
presence of massive BLACK HOLEs" (or whatever), then you will be able  
to do this by hand to some extent given a good knowledge of all the  
available VO tools, but there's no way for a computer to have any  
idea what your asking for.

I hardly think it's necessary to put together more justification than  
this.  If VO tools don't presently use vocabularies, then they  
obviously aren't very powerful, because that means that humans are  
constantly being used to perform many stupid vocabulary  
identifications and connections which a computer could do just as  
easily (or better) if it only knew how ;-)

Rick

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Dr. Frederic V. Hessman     Hessman at Astro.physik.Uni-Goettingen.DE
Institut für Astrophysik          Tel.  +49-551-39-5052
Friedrich-Hund-Platz 1         Fax +49-551-39-5043
37077 Goettingen                 Room F04-133
http://www.Astro.physik.Uni-Goettingen.de/~hessman
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