Spectrum data model

[Jonathan McDowell]

: Ach, what I actually thought you meant was the parent collection (e.g. if 
: the particular instance of Spectrum was describing one spectrum out of a 
: collection of 20 Markarin galaxies....). Shows how some idiot will always 
: get the wrong end of the stick however carefully it is worded!

This is covered by Spectrum.DataID.Collection

: >> Spectrum.Char.SpatialAxis.Coverage.Bounds.Extent: Bounds is box
: >> corners in Char; I can see confusion if it is a diameter in Spectrum -
: > Well, the idea is that Bounds.Extent is an alternate representation
: > of the same information in Bounds.Min/Bounds.Max. It's more appropriate
: > for spectra, but you can convert it.
: 
: Sorry, I don't agree, I think that it will confuse both data providers and 
: software.  If I have data in Char with a box described by square Bounds, 
: with data in the corners, I have to take the radius along the diagonal to 
: convert it to Spectrum Bounds.  Then if I convert the Spectrum Bounds back 

We could define it to be the extent parallel to the axes... of course
you need the proper Spectrum.Char.SpatialAxis.Coverage.Support.Area 
region to accurately define the aperture. 

: If things have the same name they should be the same thing.

I agree at the level of the leaves: Bounds.Max needs to always
mean the same thing. But Bounds, as a complex object, can have
different flavors.

: Maybe we should give up trying to make this model evenhanded for data 
: which do not have the main axis in the e-m spectrum. What do time 
: series/VOEvent people think? Are they catered for well enough with Char 
: and the specific time domain models, for data which the present version of 
: Spectrum does not fit?

It is true that we are really concentrating on the spectral
application for now, while trying to leave it open for time series.


: But there are now many VO-enabled  tools which handle spectra with varying 
: degrees of speciality (SpecView, VOSpec, TopCat, SPLAT....) which can read 
: a wide variety of formats (and contrariwise, image FITS can be quite 
: perverse...)

They read some formats, but there are plenty they don't.
And if we don't provide some recommended ones, the zoo of spectral
formats will continue to spread.

: Apologies for misunderstanding; if I have now got it straight, then " 
: Spectrum.Data.SpectralAxis.Value " etc. are only compulsory if you are 
: using the xml format for your data.  I think that somewhere early on e.g. 

Or the FITS version defined in the doc.


 cheers, Jonathan