Spectra DM for theoretical spectra?

[Petr Skoda]

On Tue, 2 Jun 2009, Carlos Rodrigo Blanco wrote:

> The main point, as I see it, is that the SpectrumDM is designed having 
> observed spectra in mind, no theoretical ones.

> The model contains everything that is necesary to describe the content of a 
> spectrum (the wavelength, flux and all that, and this is the same for 
> observed and theoretical ones) but nothing of what is needed to 
> __characterize__ a theoretical spectrum.

I see that Carlos was quicker then I - have read this just after finishing 
my objections (basicaly the same as Carlos).

I see the problem not only in characterization of metadata in the SDM
but generally in the attitude ov VO community to the spectra and 
especially theoretical ones. I see in everyday science that most 
discoveries are done by comparison of theoretical results of given model 
with observation - but it is done in a highly ineffective way - mostly by 
manual comparison case by case.
The VO could here extremely rise the scientific productivity and attract 
the researches to use it as here is the breakpoint where the even very 
conservative astronomer would prefer to go the VO way in comparing 
hundreds of models with  his observation.

The DEMOs like "get 1 spectrum from this telescope and overplot this 
Kurucz model" is nice but the real science needs more.

So I suggest the SVO group should revise the TSAP (called e.g. S3;-)
and start the SSAv2 from this side. As I have seen there is no priority on 
spectra extension in the DAL, the Theory group may be the proper driver.
I will be happy to collaborate on this effort.

I see that the problem of describing model parameters may solve some 
problems I see with proper SSA of observed spectra - e.g. the way how they 
were reduced (e.g. the usage of optimal extraction, removal of telluric 
lines, convolution with instrumental profiles .... , how the continuum was 
applied) is resembling the same issues as how the theory spectra were 
created ..... we need both query parameters and characterization 
(provenance) metadata to distinguish between different version of spectra 
as results of different processing ....

In a some sence are all spectra only theoretical ;-)
as the observed ADUs directly detected on given pixels are converted to 
what we call "observed spectrum" by the theoretical model of the 
instrument and mathematical methods that seems to be obvious for the given 
instrument.

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*  Petr Skoda                         Phone : +420-323-649201, ext. 361 * 
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