[Passband] diverting into SEDs

[Guy Rixon]

On Mon, 31 May 2004, Martin Hill wrote:

> So far I see an SED as being a collection of 'SED Measurements', each
> measurement being a Flux, a Passband, some kind of Frame of reference, etc.  It
> may be that an SED could include a spectrum; if someone has for example measured
> an optical spectra and wants to combine it with an X-ray count.  But I suspect
> there will be many more things required in SEDs, so I would like to leave them
> for a bit...

This is a case of the "list-of-congruent-objects" thing that I was talking
about last week in Boston.

If we model an SED as a list of objects, we may choose to store it differently
(e.g. 1D FITS image giving fluxes with keyword-value pairs for errors and bin
widths and a WCS for wavelength/frequency/energy). In that case, we badly need
a way to write the mapping between the model and the storage.

> Be careful here as you're starting to mix 'representation' with the model.  When
> we come to modelling SEDs we simply say that the SED must/could 'have' stellar
> atmosphere/filter/etc data.  Whether this 'haved' data is remotely accessed or
> passed along with the rest of the SED is a representation issue we need to sort
> out (later).

Quite.

Guy Rixon 				        gtr at ast.cam.ac.uk
Institute of Astronomy   	                Tel: +44-1223-337542
Madingley Road, Cambridge, UK, CB3 0HA		Fax: +44-1223-337523