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:
(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) P.O. Box 50727 E-28080 Villafranca del Castillo MADRID - SPAIN ================================================================================================ This message and any attachments are intended for the use of the addressee or addressees only. The unauthorised disclosure, use, dissemination or copying (either in whole or in part) of its content is prohibited. If you received this message in error, please delete it from your system and notify the sender. E-mails can be altered and their integrity cannot be guaranteed. ESA shall not be liable for any e-mail if modified. =================================================================================================Received on 2006-10-23Z19:15:52attached mail follows:
Dear Jonathan, at the VOTech meeting at Sorrento, I touched again on the issue of the absence of a proper model for photometry. There was a general agreement there that we needed a proper model for Photometric data, and a small group of people volunteered to create an effort in this direction. I said that any DM effort should go in a common IVOA direction, and hence I am forwarding you the mail I have sent to this group of people. Our intention is that you give your blessing for it, and then we present at Victoria why we are creating the group, what we are trying to solve and then invite people to join. Could you please have a look at the mail and let me know whether you'd agree on the approach? Thank you. Cheers, P. -- Pedro Osuna Alcalaya ESA Science Archives System Engineer Science Archive Team European Space Astronomy Centre (ESAC/ESA) e-mail: Pedro.Osuna-at-esa.int Tel + 34 91 8131314 --------------------------------- European Space Astronomy Centre European Space Agency P.O. Box 50727 E-28080 Villafranca del Castillo MADRID - SPAIN
attached mail follows:
Dear all, as agreed at the Sorrento meeting, I take the action to invite you to a small group of people willing to create a proper Data Model for Photometric data. I have been waiting this time because Peppe Longo was preparing a document that I wanted to serve as our starting point, but unfortunately there has not been time enough to have it ready yet (although I know it is in its way). The idea is briefly to build a model for photometry, where _any_ thing needed to work with photometric data is available and well described. In general, a photometric measurement is the result of a series of convolutions of different functions, and the idea is that the model contains all possibilities: from simple reference wavelength plus zero point data, to complex response curves, filter curves, etc. I would like to propose to the IVOA in general the endorsement of a possible Photometry model that would be "plugged in" to the SED data model. I think any Data Model effort should be "blessed" by the IVOA, hence I will forward this mail to Jonathan to make him aware of what we might be working on. Eventually, we should then propose in Victoria the official creation of a subgroup for this, but then Jonathan would have to give his official go-ahead or otherwise. I would also like to invite some people from other sides of the world, and in particular I think that Tamas Budavari (JHU) should be in the group. I am sure that there might be other people wanting to join the effort, so it might be worth to go to Victoria with a brief outlining of what the problem is, why we want to solve it and to invite people to join. Please send me anything that might me coming to your head related to photometry; I will then collect information and prepare a small presentation for Victoria on why we need the group and what we are trying to solve (_not_ about how to solve it, yet). We will then afterwards start thinking on how to tackle things.... I think I have collected all the people we agreed at Sorrento, plus Matteo, whom I have added myself. Let me know if you want someone else to be in. Please send me any comments, suggestions or inputs soon. Thank you. Cheers, P. -- Pedro Osuna Alcalaya ESA Science Archives System Engineer Science Archive Team European Space Astronomy Centre (ESAC/ESA) e-mail: Pedro.Osuna-at-esa.int Tel + 34 91 8131314 --------------------------------- European Space Astronomy Centre European Space Agency P.O. Box 50727 E-28080 Villafranca del Castillo MADRID - SPAIN
attached mail follows:
Dear all, I attach the response from Jonathan wrt the Photometry group. According to him, everything can be described with the current SED and Characterization model. I think each member of this small group should have a look at it, and check whether this is true or not, and whether the creation of this group is redundant or not. If everything is really there, then there is no point in creating anything. I wait for your research...... Thanks, P. -------- Forwarded Message -------- From: Jonathan McDowell <jcm-at-head.cfa.harvard.edu> To: pedro.osuna-at-sciops.esa.int Subject: Photometry Date: Thu, 04 May 2006 15:00:19 -0400 (EDT) Hi Pedro I'm happy for you to do this with the proviso that it be consistent as much as possible with Spectrum and with Characterization. I think that between those two models pretty much everything you need, including filter response curves, is there. - Jonathan