Utypes for Light Curves?
roy at cacr.caltech.edu
Tue Jun 15 03:22:21 PDT 2010
> Have a look at Bruno's
This looks like an interesting document. Finally the Utypes are brought
out into daylight where we can see them. As I have written before, I am
interested in building a way for Light Curves to be serialized, and
building an access protocol for fetching LC from a repository. There are
several suggestions for how to represent LC ( thru  below), some
from within the IVOA community, some not. I am guessing that the Utypes
from the above is a way to elaborate the generalities of the DAL2Arch in
ref , is that right?
Following this, the Time Axis data model and Flux Axis data models look
quite relevant. I am imagining a representation of a Light Curve that
has some parameters and a table wrapped in a VOTable. The parameters and
fields will include these things from the above, for example
<FIELD utype="FluxAxis.Accuracy.StatError"/> for error in flux
<FIELD utype="TimeAxis.Coverage.Location.Value"/> for time of observation
Is that correct? If so we need a few more Utypes:
-- The FluxAxis data model does not seem to have an actual measured
value of Flux. What the Utype for the FIELD that has the flux value?
-- How do we represent the filter used for the observations? Don't we
need upper and lower limits for the filter, central wavelength, name of
the filter, that sort of thing? The Spectral DM lookslike it has some
useful Utypes, but a Spectrum is not the same a Filter.
-- How does the TimeAxis model work with STC? It says "Midpoint of
exposure on MJD scale". What time scale is this, where is the observer,
is it barycentric, etc etc. How does this sort of thing integrate with
the Utypes? Can  and  work together in this? Or maybe  and ?
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