I see questions on this list about precise definitions of UCD, and I do
not think it is relevant. We are not building a self-consistent data
model of astronomy, but rather we are pragmatically taking the list of
quantities that real astronomers have used in 5000 real tables at
Vizier.
If a table is published in ApJ that defines the "altitude" of their observatory (pos.earth.altitude), it is not for us to say the writer was a fool, it is for us to make sure there is a UCD for that concept.
Similarly, the STC is irrelevant here. If astronomical tables contain RA and Dec, then there should be pos.eq.ra and pos.eq.dec. It is not for us to say that RA and Dec do not always have unambiguous definitions.
California Institute of Technology
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Received on 2005-06-29Z12:19:21