DataLink issues

[Petr Skoda]

Hi Pat !

> My sense from the splinter sessions in Urbana was that everyone agreed with
> this idea: DataLink does not itself take much in terms of parameters *but* it
> does have to be able to describe both links to static data products data
> products and links to services that perform some processing such as you and MD
> have described.

Yes link to more specific services


> In addition to "big data" that cannot be feasibly downloaded and cutouts in
> regular data to make client work straightforward, the Theory people need this
> as well since they access to "data products" -- maybe exclusively -- that
> require cutouts of some form and often along custom axes.
  I think its OK - DL will give you "link" to another service  and 
that service will allow you to give specific parameters of given protocol

So lets say you are browsink the reply of datalinks to given object - you 
will see - ha there is a spectrum - so we can launch the predefined tool 
(e.g. SPLAT) who understands SSA and has a fields to enter parameters to 
make the cutout of given line.

The key issue is the client - it would need to understand all possible 
parameters of all protocols and build the web form - like query fields on 
the fly .....

I foresee two different modus  operandi  of astronomers:

I am searching for a bunch of spectra of my objects having the halpha line 
(or some x-ray line) and they will go directly with specific request to 
the SSA

Or they are interested what is available in VO about my objects?
So use TAP to find all observations (images, spectra etc ......, raw data 
only ...) and find - ha - they have raw data - I can run ds9 to see them 
using DL - and they have as well reduced spectra - I can run SPLAT - and 
they have images - so I will (automatically) launch Aladin)...

So it is the real discovery of VO, while the specific protocols will 
provide the more advanced and focused results (including the 
postprocessing).

Concerning big data cube - we have discussed this with Felix Stoehr and my 
solar colleagues due to ALMA.

The only feasible solution is the discovery of datacube, getting it whole 
and then apply various non-trivial algorithms to get images, intensity 
maps, spectral lines etc .... and its very hard to foresee the wishes of 
user. So The postprocessing like simple collapsing of the cube in one 
dimension does not have a scientific sense without more specific control 
which would require a lot of parameters and visual interaction.

it terms of DL - you would see there is an ALMA observation on this spot 
in given time and you would get the link to the file. If someone will do 
the postprocessing tou would see e.g. the spectra in integral beam or list 
of spectra in different spots on the sky - and you could run SPLAT to see 
the spectrum but its difficult to imagine to do the processing on the fly 
for you - perhaps using UWS to run CASA remotely .....

I am sorry to the radioastronomers for intruding their business ;-)
And sorry to the Francois for extinguishing his enthusiasm about DL 
capabilities - After sad experience with SSA potential and reality I am 
getting more realistic ......

Petr

*************************************************************************
*  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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