VOEvent 1.1 new draft with STC elaboration

[Rob Seaman]

Excellent discussion.  Suspect we lost some of the non-astronomers  
along the way.  Perhaps what we need (meaning what any pragmatic user  
of STC would need) is an explanation of why one might choose the  
different coordinate system options.  This could include astronomical  
usage scenarios and examples of converting between different  
coordinate systems (and examples of when this might not make any  
sense).  Perhaps such a document already exists?  If so, perhaps it  
might be augmented with VOEvent related scenarios?

Scenario 1:
	ESSENCE survey (http://www.ctio.noao.edu/wproject) is designed to  
detect Type Ia extragalactic SNe.  They wish to use VOEvent to convey  
alerts resulting from these detections.  The instrument is a CCD  
array on a 4m class optical telescope in the southern hemisphere.  A  
reduction pipeline generates candidate SNe detections for review and  
release by a human.  What coordinate system is most appropriate both  
for internal use by the ESSENCE team and for later followup by other  
ground-based telescopes and spacecraft?  Having received a packet  
conveying such coordinates, what steps does a responding observatory  
take to make best use of the transient alert for followup  
spectroscopic observations?

Other scenarios?

Rob