time in VOEvent (was Re: IVOA and ADASS?)

[Rob Seaman]

On Jul 2, 2008, at 2:15 PM, Roy Williams wrote:

> Good point. The time standards for VOEvent are defined as a subset  
> of the STC standard.

Rather, an excellent point!

> To quote the specification:
>
> The *coord_system_id* is built from a time part, a space part, and a  
> center specification, concatenated ion that order with hyphen as a  
> separator.
>
>   * The time part can be UTC (Universal Time) or TT (Terrestrial
>     Time). Currently, TT - UTC = 65.185 seconds.

The latest wording (section 3.4.1) also includes TDB.  We can worry  
about TCB if anybody actually starts using it :-)

>   * The space part can be "FK5" or "ICRS" (for which the coordinates
>     are right ascension and declination),
>   * The center specification can be TOPO (surface of the Earth), GEO
>     (geocentric coordinates), or BARY (barycentric coordinates).

I propose that we reference VOEvent time series data - whatever the  
schema, whether expressed as MJD or millifortnights - to this exact  
set.  No more, no less.

All in favor?  None opposed?

Rob