[Radioig] ObsCore Extension for visibility data

[BONNAREL FRANCOIS]

Dear radioIG members,

We want to recall you that an IVOA ObsCoreExtension note exists and can 
be found on github here : 
https://github.com/ivoa/ObsCoreExtensionForVisibilityData

We encourage you to read it and post some comments or issues here or on 
github.

This is a list of  questions which are still under discussion or should be:

       - how to give access to spectral ranges in frequency ?

       - how to estimate min and max distances in the uv plane ?

       - should we have a single Obscore+ extension table or just create 
a new VisObsCore table with the new proposed attributes and on which 
column do we join the two tables ?

       - how do we access maps useful for quality/relevance estimation 
of the data (uv coverage maps, dirty beams, etc ...) . Via DataLink or 
direct integration in the extension ?

      - probably others (for example how do we advertize availaibility 
of this  extension in registering ObsTAP services )....

Cheers

Mark Lacy and François