Spectral 2.0 - Document update

[Petr Skoda]

Hi Mark and all DM members

Unfortunately I do not have time to go through tiny details of SDM 2.0
But I would like to be assured (by you) that there is a simple answer to 
these issues:

1) normalized spectra -  I mean continuum normalized (i.e the horizontal 
line of continuum is at 1.0)
Those do not have by definition units - its just relative ratio - it was 
somehow defined in older SDMs as a ration and some reference (but no one 
defined yest how to refer to the description of contiuum) - in practise 
all usefull optical spectra should be continuum normalized by pipeline 
(or manually) already before ingesting in SSA services ....
How to describe the Fluxunit and UCDs on flux etc ..... ?

2) The wavelength of practically all optical spectra from ground (et least 
those in current SSA services) is a wavelength in AIR !!!
It is exactly what comes out of pipelines and reflects the observing 
conditions (temperature, humity ...) .
The conversion to vacuum wavelengths is not trivial and requires some 
provenance values .... and moreover it would not be much useful for most 
people as they know (by heart) only air wavelengths and expect them ....

But SDM and SSAP define implicitely all wavelenghts in vacuum ....

So in principle all current SSA services are faked !!! They are not 
compliant at all with standards ...

The (hacked) solution is to deliver label on X axis as "air wavelength"
but in principle we may not use the current SDM and SSAP with calm minds 
....

3) SDM2 and SSAP2 aspire to be able to handle the time series ...
then the spectral units should be time units, bands as wavelength 
ranges are changing into formal 
description of photometric filters (and somehow converted to real band 
ranges) - there was a discussion last year ...

is this possibility reflected in definiton of axes and their labels ?
I suppose we should tacle this in Sesto  ....


Best regards

Petr

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*  Petr Skoda                         Phone : +420-323-649201, ext. 361 *
*  Stellar Department                         +420-323-620361           *
*  Astronomical Institute AS CR       Fax   : +420-323-620250           *
*  251 65 Ondrejov                    e-mail: skoda at sunstel.asu.cas.cz  *
*  Czech Republic                                                       *
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