Re: UCDs in SpectrumDM

From: Frederic V. Hessman <hessman-at-Astro.physik.Uni-Goettingen.DE>
Date: Mon, 25 Jun 2007 09:59:15 +0200

On 23 Jun 2007, at 8:52 pm, Jonathan McDowell wrote:

>
> Andrea,
>
> I guess I don't feel that
> phot.flux.density;em.wl,stat.max
> (and similar) are 'cumbersome' - I find them much easier
> to understand than extra custom-crafted UCDs like ..perWave.
> I feel that em.wl, em.freq, etc. are naturally adjectives as well as
> nouns

> For em.*: in the context of the doc, this is a shorthand for
> (EITHER em.wl OR em.freq OR em.energy).

I confess that I have a hard time with all of these solutions, since they are workable only if the assumptions behind them are clearly defined (and who is going to garantee that someone teaches a computer correctly?).

In order to manipulate the numbers, the VO apps are going to have to deal with the units anyway, so I'd prefer one of two extreme solutions:

  1. em.flux THAT'S IT! Whether it's W/m^2/micron or Jy or photons/ cm^2 .... can only be known by looking at the units.

or

2. Pendanticism, e.g. W/m^2/micron =
em.energy;stat.perSqrMeter;stat.perTime;stat.perWavelength

I know these comments are late - so you can promptly delete this email - but these seem much more workable solutions.

Rick



Dr. Frederic V. Hessman     Hessman-at-Astro.physik.Uni-Goettingen.DE
Institut für Astrophysik          Tel.  +49-551-39-5052
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Received on 2007-06-25Z07:59:29