STC ObservationLocation

[Roy Williams]

Arnold

I would like to ask a question about the structure of the STC system,  
in particular it is the old chestnut about the element  
ObservatoryLocation.

Of course, if I specify that the coordinate frame is centered on  
TOPO, then it means I need to specify where that center is -- i.e.  
the observatory location must be specified. Even for very distant  
objects, the timing information cannot be accurate without this.

BUT

Suppose I specify that the coordinates are in GEO (geocentric) or  
BARY (barycenter of solar system), then why it is necessary here to  
say where the observation was taken? Is it just that the XML schema  
is too coarse to make this fine distinction? Or is there a subtle  
matter of coordinate accuracy that I have missed?

Roy

California Institute of Technology
626 395 3670

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