<p dir="ltr">Petr, </p>
<p dir="ltr">Regarding your second point, that is one more reason why wavelength is such a bad choice for spectral coordinates. Frequency makes much more sense and has the advantage that its conversion to the third type, energy, is linear - it's two against one :-) <br>
But you alerted me to the fact that I need to add another property to the wavelength variant of the spectral coordinate in STC2.</p>
<p dir="ltr">Cheers, </p>
<p dir="ltr"> - Arnold </p>
<div class="gmail_quote">On Jun 4, 2015 8:46 PM, "Petr Skoda" <<a href="mailto:skoda@sunstel.asu.cas.cz">skoda@sunstel.asu.cas.cz</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi Mark and all DM members<br>
<br>
Unfortunately I do not have time to go through tiny details of SDM 2.0<br>
But I would like to be assured (by you) that there is a simple answer to these issues:<br>
<br>
1) normalized spectra - I mean continuum normalized (i.e the horizontal line of continuum is at 1.0)<br>
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 ....<br>
How to describe the Fluxunit and UCDs on flux etc ..... ?<br>
<br>
2) The wavelength of practically all optical spectra from ground (et least those in current SSA services) is a wavelength in AIR !!!<br>
It is exactly what comes out of pipelines and reflects the observing conditions (temperature, humity ...) .<br>
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 ....<br>
<br>
But SDM and SSAP define implicitely all wavelenghts in vacuum ....<br>
<br>
So in principle all current SSA services are faked !!! They are not compliant at all with standards ...<br>
<br>
The (hacked) solution is to deliver label on X axis as "air wavelength"<br>
but in principle we may not use the current SDM and SSAP with calm minds ....<br>
<br>
3) SDM2 and SSAP2 aspire to be able to handle the time series ...<br>
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 ...<br>
<br>
is this possibility reflected in definiton of axes and their labels ?<br>
I suppose we should tacle this in Sesto ....<br>
<br>
<br>
Best regards<br>
<br>
Petr<br>
<br>
*************************************************************************<br>
* Petr Skoda Phone : <a href="tel:%2B420-323-649201%2C%20ext.%20361" value="+420323649201" target="_blank">+420-323-649201, ext. 361</a> *<br>
* Stellar Department <a href="tel:%2B420-323-620361" value="+420323620361" target="_blank">+420-323-620361</a> *<br>
* Astronomical Institute AS CR Fax : <a href="tel:%2B420-323-620250" value="+420323620250" target="_blank">+420-323-620250</a> *<br>
* 251 65 Ondrejov e-mail: <a href="mailto:skoda@sunstel.asu.cas.cz" target="_blank">skoda@sunstel.asu.cas.cz</a> *<br>
* Czech Republic *<br>
*************************************************************************<br>
<br>
<br>
<br>
<br>
<br>
</blockquote></div>