WD-AccessData-1.0-20140312

[Petr Skoda]

Thanks for explanation of the plans.
>
> WD-AccessData-1.0 will support a single set of fixed units:
>
> * POS is ICRS degrees
OK it is the most expected query of everyone  (after conversion from HMS 
to deg by client)


> * BAND is barycentric wavelength in meters
Well same as SSA .
Used for selection of spectral lines works well

But tell me how to select the photometric R band  image !

I know it is named R but the exact range depends on a manufacturer of the 
filter (some may have leaks)
So if I look in the literature I can get some value (to query for) but the 
metadata in characterization may give another range of wavelengths - I may 
not fit into so I will need to try wider range several times ....
And to be honest - lot of photometric surveys simply tell it is this item 
from the list of our filters (e.g. in SDSS you get only u,g,z or so - )
it may be a detective work to match the proper filter range either to 
query it and namely to extract only what I want .

What are the reason not to allow names (letters) whatever they mean (the 
scientist will sure know what he wants)?


I do not insist on symbolic names but as a scientist I want to know how 
can I select the only one band image from set of several - or from 
multi-extension FITS with several colours.


> * TIME is UTC but allows MJD or timestamp strings
OK as in SSA  - proved to work

>
> This is the minimal simplest thing that meets the CSP use cases and can 
> pretty easily cover common (90% or more of) use cases. This is the same 
> restriction as in the WD-SIA-2.0 {query} capability.

the biggest mistake of SIA 1.0 is there is not primary the concept of 
filters built-in - I am just in troubles trying to access the multi 
colour survey.

I do not believe the most use cases can be solved by stating 
wavelengths in BAND....