Make sure VOTable definition is up to date

[MatthewWhiting]

Been a while since I looked at VOTable standards. Check them to make sure the VOTable format being used is correct and sufficient.

[MatthewWhiting]

Some links:

• VOTable : ​http://www.ivoa.net/Documents/VOTable/20091130/REC-VOTable-1.2.html
• STC (Space-Time Coords): ​http://ivoa.net/Documents/latest/STC.html
• UCD1+ - ​http://www.ivoa.net/Documents/latest/UCDlist.html

Some notes:

• We currently have J2000 etc hard-coded into the VOT header - this should reflect the WCS of the image.

• Check the UCDs, as the specs may have been updated

[MatthewWhiting]

Given #135 and the desire to improve the VOTable output, moving this ticket to 1.1.14 release.

[MatthewWhiting]

I'm going to defer this to a later milestone - I want to get 1.2 released sooner rather than later, and I'll need time to work through the new STC. Have made a slight improvement to the VOTable coordinate system, where it does actually respond (albeit poorly) to the coordinate system type. This needs revisiting though.

[MatthewWhiting]

A note about referencing STC in a VOTable can be found at: ​http://www.ivoa.net/Documents/Notes/VOTableSTC/

[MatthewWhiting]

Move this to 1.2.1 for evaluation.

[MatthewWhiting]

Still think this requires a bit of thought. Want to do it right, but also want to get 1.2.1 out sooner rather than later, so will bump it back up again.

[MatthewWhiting]

Hmm, looking at this again. A bit tricky, and if we want to do this then it makes sense to do it properly and not just a half-baked hack. Perhaps defer again to release 2.0...

[MatthewWhiting]

Given #206, move this into 1.6 so we can get the STC right at same time as namespaces and update to VOTable 1.3

[MatthewWhiting]

Closing this, as sufficient for 1.6 purposes.

Defer STC incorporation til 1.7 - see #223