time series with sparse em axes

[Baptiste Cecconi]

I Marco, 

if I understand well, you have 3 dynamic-spectra (each having 6 spectral channels).
The http://www.ivoa.net/rdf/product-type#dynamic-spectrum data product should applicable. 

In epncore, this should be no problem to describe the spectral axis. Nothing prevents to have sparse spectral axes in the datasets. 

Cheers
Baptiste


> Le 24 mars 2025 à 09:47, Markus Demleitner via semantics <semantics at ivoa.net> a écrit :
> 
> Hi Marco,
> 
> On Fri, Mar 21, 2025 at 06:26:59PM +0100, Molinaro, Marco via semantics wrote:
>> for a "heritage data" project we have a set of observations
>> that consist of time series of nearly monochromatic RHCP & LHCP
>> radio fluxes of the full disk Sun.
>> 
>> Unfortunately the files they are stored in (FITS bintables)
>> contain:
>> - the 6 individual observational frequencies, sparse from 237Mhz to 2.7GHz
>> - for each of them 3 time series: LHCP, RHCP and the sum of them (full flux)
>> 
>> This leads us to describe them, no matter if in obscore or epncore,
>> as 6 separate time series records referencing the same FITS dataset,
>> because we are unable to describe the sparse "em" axes.
> 
> Well, as long as the time axis is sampled uniformly, there is nothing
> that would keep you from having just one time series with 18 columns,
> and I believe clients like SPLAT would do a reasonable job displaying
> them.
> 
> If the time axis is not sampled uniformly over all frequencies, I
> think I'd go for per-frequency time series with one column each for
> the three observation modes.
> 
> All that is based on what I think will make this data easy to work
> with with generic VO tools, completely independently of the
> underlying physics and in particular community practice.  Therefore:
> 
>> Or maybe Radio, HE, TD IGs have some insight on this.
> 
> I'd frankly ask Solar System first (and its vice chair already
> confesses he can't help here).  I'd say *if* there's some dominant
> practice in the community, whatever format that calls for is what I'd
> serve up by default; and then I'd attach a datalink that yields
> SDM-compliant tables with Ada blocks (:-)
> <http://ivoa.net/documents/Notes/LightCurveTimeSeries/index.html>
> for interoperability beyond that community.
> 
> Consider this as not much more than my 2 cents, though.
> 
>        -- Markus
> 

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