VOEvent 1.1 new draft with STC elaboration

[Rob Seaman]

On May 16, 2006, at 10:30 AM, Arnold Rots wrote:

> I suggest the following standard systems:
>
>   UTC-HPC-TOPO
> 	Describes raw observational data
>   UTC-HELIO-HPC-TOPO
> 	For time-corrected observational data
>   UTC-HGC-HELIO
> 	Suitable for reporting solar events
> The following seem useful:
>   UTC-HELIO-HEEQ-TOPO
>   UTC-HELIO-HCC-TOPO
>
> Are there any among these that you don't expect to be used at all?
> Are there any among these that you don't expect to be used in VOEvent?
> Are there others that you expect to be used?

And exactly *how* are these going to be used?  Perhaps the answer to  
this might shed some light on the nighttime usage, as well.  Does the  
workflow go something like:

	1) use an XQuery to fetch the coordinate system identifier (as above)

		1b) throw an exception if system is not supported (or is unrecognized)

	2) consult a table of what coordinate quantities (e.g., RA, Dec,  
Epoch, + errors in each for UTC-FK5-GEO) to expect

		2a) perhaps this table would also convey units, ucds, default  
values, etc?

	3) use an XQuery (or whatever) to fetch the values for the  
appropriate quantities

	4) descend through a tree of conditionals depending on system and  
values

		4a) many branches would throw exceptions

		4b) some branches would allow parsing to succeed

Was wondering about separating the timelike and spacelike points of  
view myself.  A little bit of this might result in a renewed interest  
in generating separate SC and TC schema :-)

Am copying this message to Frank Hill.  Among other things, am  
wondering what sense there is in calling solar coordinates  
"topocentric", if time is being handled separately.

Rob