Revised ImageDM-ObsCore architecture

[Douglas Tody]

On Tue, 12 Nov 2013, Douglas Tody wrote:

> On Tue, 12 Nov 2013, CresitelloDittmar, Mark wrote:
>
>>  an abstract ObservationDataset class.   (I have trouble here, because the
>> Image/Spectral
>>  classes need DataID,Target,Curation objects which are Bigger than what is
>> in ObsCore.)

The current Image/Spectral DataID, Target,Curation elements are somewhat
bigger than what Observation defines, but not that much.  Note the more
complete version of the model is in Appendix B.  DataID for example,
defines six elements but only two are in the mandatory "core".  Spectral
and Image do add a couple more.

These are purely generic classes, not specific to images or spectra.  I
think what we want to do here is merely add them to the next version of
Observation, i.e., ObsCore (the document attempts to define the full
model as well as the Core Components; we just ran out of time to include
everything).  In any case, if Image and Spectral extend Observation then
we can add new fields.  It is just that if they are generic they should
really be in the base model.

 	- Doug