relative fluxes

Petr Skoda skoda at sunstel.asu.cas.cz
Mon Jun 29 14:31:18 PDT 2009



> - More importantly, in my opinion it will take more work to generate the
>  needed metadata than to reformat the FITS files. That work will be required
>  whether the metadata is to be added as FITS keywords or just written to the
>  VOTable response.


Here should help the practical example and perhaps some convertor using 
FITS keywords to write metadata (something like Mex) but in a practice:
what is important in FITS header except of  date, time, exposure length,
spectrograph parameters ... is 
observatory, telescope, instrument.... which is usually static for given 
type of data and spectral info (CRVAL1, CDELT1, CRPIX1 NAXIS1) and HJD.

The FITS header are typicaly stored to some kind of DB tables as they are 
required for generating observatory reports, giving idea what has been 
already in the archives etc .... But it is only work with headers and db 
tables - many observatories have to do it anyway.

So to tell somebody - use this info from your fits header database and 
generate other db columns with strange (VO Dm ;-) names and you have the 
VO server is well
understood by potential publishers and modified accordingly,
But once they are required to go to fits files and modify them is much 
more demanding.
If you had a simple task to convert e.g.     fitstobintab *.fits *.binfits
it might still work - but give me such a task !


> I guess its left to be seen whether officially supporting this format is 
> enough
> incentive for observatories to register new SSAP services. If it is, I would 
> support

There is, of course, a lot of other obstacles. E.g. data jealousy or fear 
of loosing strategic trumps, unawareness and underestimation of creating 
archives, very limited usage of data (only several object under study, but 
long-term monitoring of others just for future analysis - there is a lot 
of interesting cases - e.g. when the emission phase appears after several 
years - you have to monitor and see the same spectrum all the time until 
the day D;-)
And if all of this is overcome here it comes the final strike:
What to do with my data ?

( I supposed to upload it somewhere - but there is need to convert it to 
bintable - how ? And I will have two different versions - how to maintain 
it?)

The question is solved by delivering small publishing platform 
(prepackaged server when only some fields are filled, the FITS header is 
extracted - some mapping of keywords to dm checked manualy, deploy  and 
thats it 
-we have the SSA server.

But it is still not there, although eg. SAADA is approaching it (but I am 
not sure about 1D FITS mapping - probably there is still work ongoing)
DALToolkit as well - but only for bintables.

But the 1DFITS to bintable  converter has to be the part of it as well !
Who will do it ?

*************************************************************************
*  Petr Skoda                         Phone : +420-323-649201, ext. 361 * 
*  Stellar Department                         +420-323-620361           *
*  Astronomical Institute AS CR       Fax   : +420-323-620250           *
*  251 65 Ondrejov                    e-mail: skoda at sunstel.asu.cas.cz  *
*  Czech Republic                                                       *
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