comments to SDM 1.01

[Dobos, Laszlo]

It also might be useful to reconsider the whole unit system notation keeping
in mind further issues, like automatic unit conversion. We already have a
problem with Angstroms (though using only SI units can help overcome this
problem but makes the life of vo client application developers more
difficult), because angstrom and amper are noted with the same letter using
the ascii charset.

On the otherhand, I would not introduce any unit describing normalization or
whatever else. First of all, characterization has a field for calibration,
that's perfectly enough and appropriate to describe if the flux axis
represents normalized values (for example setting the field to NORMALIZED
implies the fluxes are indeed spectrophotometrically calibrated relatively
to each other).

However, it still would be useful to describe different normalization
methods. One can normalize spectra to a given flux at a given wavelength,
but in stellar population synthesis fluxes are normalized to represent the
emission of a star population with one solar mass.


Cheers

Laszlo

-----Original Message-----
From: owner-dm at eso.org [mailto:owner-dm at eso.org] On Behalf Of Petr Skoda
Sent: Wednesday, August 22, 2007 4:29 PM
To: dm at ivoa.net
Subject: comments to SDM 1.01


As I have emphasized in dal group, the normalized spectrum is a important
fully science ready output and thus it is not equivalent to ignore the flux
axis by stating the units as "n/a" and telling the units to be "unitless" -
but is is perfect quantitative and measurable information on normalized
spectra - so I propose the special notation for such a "unit" as a "1" (one)
or if letter required as "U" (unity) or "N" (normalized)