[obs-tap]observable quantities in observations and their UCDs

[Anita M. S. Richards]

Good point, and in fact radio data are often provided adjusted to constant 
Vlsr.  However, the rest frequency of the reference line is then required 
also.

cheers
a

On Wed, 23 Jun 2010, Douglas Tody wrote:

> While this is technically correct I suggest the solution is to merely
> generalize the concept of "observable" a bit, since actual datasets
> from telescopes can be delivered with this quantity as the "observed"
> value, and the observation is often explicity intended to produce
> a velocity.  The same thing goes for other similar cases, e.g., a
> normalized spectrum is not directly observed, but we have them in
> our archives and need to describe them and deliver them to users.
> Instruments are increasingly complicated and may well do some
> processing beyond just what can be directly observed physically.
> - Doug
>
>
>
> On Wed, 23 Jun 2010, Igor Chilingarian wrote:
>
>> Hi Mireille,
>> 
>> As I already mentioned in our discussion here at CDS, I do not think that 
>> "velocity" is observable in any sense. I would agree that it can be a 
>> spectral coordinate, but we NEVER directly observe velocities. Velocities 
>> are results of the [model-dependent] data analysis.
>> 
>> With best regards,
>> 						Igor
>> 
>> On Thu, 17 Jun 2010, Mireille Louys wrote:
>> 
>>> Dear DM members,
>>> 
>>> At the last interop in Victoria, we decided to build
>>> up a list of observable quantities that are measured in an observation
>>> and to attach to it a proper Ucd. These will be the observables
>>> considered for the Obs/Tap specification .
>>> 
>>> I gathered material from the Polarisation Note and Interferometry note by 
>>> Anita.
>>> I included items from Francois's observable list.
>>> 
>>> Please find here a table to start with for this.
>>> 
>>> Thanks for your inputs, comments and corrections.
>>> 
>>> Best regards, Mireille
>>> 
>>> 
>> 
>