units symbols

[Anita M. S. Richards]

Thanks very much Jesus,

The VOSpec model will be very useful.

Please can I ask anyone with important information or comments, especially 
references to useful documents, to put them on the wiki page

http://www.ivoa.net/twiki/bin/view/IVOA/UnitsDesc

thanks

Anita

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Dr. A.M.S. Richards, AstroGrid Astronomer, University of Manchester, 
Jodrell Bank Centre for Astrophysics, Turing Building, 
University of Manchester, M13 9PL
+44 (0)161 275 4124
and
MERLIN/VLBI National Facility, Jodrell Bank Observatory, 
Cheshire SK11 9DL, U.K. +44 (0)1477 571321 (tel) 571618 (fax)


On Thu, 4 Oct 2007, Jesus Salgado wrote:

> Dear all,
>
> I have been reading the different valuable contributions about the
> different standards for units and, more than ever, I think the purpose
> of the creation of a work package inside the DM group for unit
> description is to define what a unit is.
>
> I could be wrong but the final output I expect is a data model, not a
> recommendation of which standard should be adopted. Of course, as a
> consequence of this effort, one existing standard could be recommended
> because we would be able to analyze the different existing standards
> with more information and to estimate if one of the standards is better
> than the other.
>
> As you already know, in VOSpec we already work with a mini-model for
> units that could be defined as:
>
> - String representation
> - UCD
> - Scaleq
> - Dimeq
>
> (see http://arxiv.org/pdf/astro-ph/0511616)
>
> The problem is not so simple as, for the conversion of units, a
> "conversion object" should be created with no only the initial and final
> unit for the conversion, but the numerical value of the magnitude, the
> constants that characterize the problem and other magnitudes of the
> problem (with their values and units), as all of them could be needed in
> the conversion (all of them would be the "dimensions" of the problem).
> This is a quite general procedure and, in my opinion, it is a good
> starting point to start the abstraction of a units data model.
>
> We will document this approach properly as a contribution to the work
> package.
>
> Best Regards,
> Jesus
> -- 
> Jesus J. Salgado
>
>
> ESAC Science Archive Team
> e-mail: Jesus.Salgado at sciops.esa.int
> Tel + 34 91 8131271
>
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>
>
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