Photometry in VO Spectrum Model

[Pedro Osuna]

Hi all,

we are not discussing about the protocol, we are discussing about the
Data Model, as an abstraction of the data that represents properly those
data. How to access them would be another issue.

Some time ago I sent Jonathan a note in which I asked him for the
blessing to create a small group working on Photometry data model
definitions. I attach the mail I sent to Jonathan and his response
(claiming that he believed everything related to photometry could be
done with the current model). 

I think that modelling of Photometric data should be done properly, and
in view of the fact that it is not precisely a trivial issue, probably
the best at this time would be to:

1) release SED as is (without photometry description)
2) create a small group working on a model for Photometry as separate
(or complementary or whatever) to the SED one. 

(In passing, I believe the same should be done for Time Series: create a
proper model complementary to the SED but somehow separate (Pavlos
Protopapas told me he has written something on this already....))

If you'd agree with this approach, Jonathan could eventually give his
blessing and an effort could be started to create the Photometry Data
Model. We already identified a list of people interested in belonging to
this effort (see the emails attached) within EURO-VO and could add to an
IVOA overall effort.


Cheers,
P.




>I can see that one might want to plot a spectrum in magnitude units in
> a standard system.  A good question to consider however, is whether this
> feature belongs in the user interface, where the spectrum is plotted in
> whatever units the user prefers, or in the protocol.On Mon, 2006-10-23 at 09:09 -0600, Doug Tody wrote:
> Hi All -
> 
> On Mon, 23 Oct 2006, Pedro Osuna wrote:
> > it was me who proposed the photometry thing.
> >
> > It is astronomers who like to do this "strange" things Doug, like liking
> > to share data in magnitudes rather than real fluxes. I can give you many
> > examples of those cases (whether "sensible" thing to do or otherwise is
> > another issue), but just have a look yourself at Vizier using the old
> > UCD system to guess how many catalogues there are there with photometric
> > points (for instance, Johnson J):
> 
> I can see that one might want to plot a spectrum in magnitude units in
> a standard system.  A good question to consider however, is whether this
> feature belongs in the user interface, where the spectrum is plotted in
> whatever units the user prefers, or in the protocol.  This is similar to
> displaying RA/DEC in sexagesimal units, while we use decimal degrees in
> the protocol.  This sort of conversion is easily handled in the user
> interface.
> 
> 	- Doug
-- 
Pedro Osuna Alcalaya

European Space Agency (ESA)
European Space Astronomy Centre (ESAC)
Research and Scientific Support Department (RSSD)
Astronomy Science Operations Division (SCI-SD)
e-mail: Pedro.Osuna at esa.int
Tel + 34 91 813 13 14    Fax: +34 91 813 11 72
-------------------------------------------------                                                                                
European Space Astronomy Centre (ESAC)
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E-28080 Villafranca del Castillo
MADRID - SPAIN
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