Time series: Annotation of light curves in VOTable

[Mark Taylor]

Francois,

On Tue, 21 Apr 2020, François Bonnarel wrote:

> after discussion with Laurent Michel and Ada I have two points  to address.
> 
> 1 ) I think it's better to mark the VOTABLE as being a timeseries right at the
> beginning of the document instead of putting the utype="timeseries"
> information at the beginning of the TABLE.

I don't understand this comment - I don't see utype="timeseries"
anywhere in the current text.  There is utype="timeseries:PhotometryPoint"
(along with a sidenote that it needs more explanation), but that's
not (necessarily) at the beginning of the TABLE, it's in the
PHOTCAL GROUP.
In any case I don't agree that the start of the document is the right
place to specify that a timeseries is included - perhaps somebody
wants to put some time series tables and some other tables in the
same VOTABLE document.  Why do you want to do this?

> 2 ) In the current note the multiband case is serialized as 3 tables written
> in sequence. Each table has its own PhotCal GROUP attached. In the attached
> example (discussed with Ada) we propose an alternative: a single table with a
> "FilterIndentifier" column. 3 different Photcal GROUPS are attached to this
> tabel and the appropriate Filteridentifier PARAM in each of these group is
> referring to the column with the same name  in the TABLE. The assumption is
> that photometric metadata given in the GROUP are valid for all roaws where
> values of FilterIndentifier in the row and in the GROUP PARAM match.

By the "FilterIndentifier" column I presume you mean the one with
name="photometric_filter" in the example.  What values actually go
in this column? there's nothing written in the example.
Guessing some possible answers to that question, I'll note that
using a table written in this form is likely to be quite a bit
harder for clients than the proposal in the Note text.

Mark

--
Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
m.b.taylor at bris.ac.uk +44-117-9288776  http://www.star.bris.ac.uk/~mbt/