About the draft itself Re: WD-SIA-2.0

[Douglas Tody]

> PS-Yes, wavelength in meters - no one's first choice :-)

Wavelength in meters is actually quite a natural unit for radio
telescopes, which predominantly observe in the centimeter, millimeter,
and sometimes meter wavelength ranges, although it is true that
frequency is more commonly used to describe the radio bands.  O/IR and
UV predominantly use angstroms, microns, and nanometers, all of which
are wavelength measures.  (But I am sure this will always be a topic
for heated discussion :-)



On Mon, 5 May 2014, Patrick Dowler wrote:

>
>
> On 14/04/14 01:00 PM, Arnold Rots wrote:
>> And what is "barycentric wavelength"? Conversion from frequency to
>> wavelength as applied at the gravitational potential at the barycenter?
>> Or does it mean to reduce the spectral coordinate to the barycenter only
>> dynamically? That's pretty inconvenient for people who are doing
>> Galactic work.
>
> The intent here is that the BAND parameter only supports one unit (m) and one 
> reference position/time/scale/hard-to-remember thing.
>
> Since we have to pick one, can you tell me the one most suitable that would 
> apply to BAND and TIME parameters. Note that the draft currently just refers 
> to the same restricted time metadata as DALI uses for literal values (time 
> scale UTC and unknown reference position). What should we use for wavelength 
> values in the BAND parameter, knowing that implementers will actually just 
> query the wavelength(s) they have in files, filter lookup tables, or spectral 
> wcs already.
>
> PS-Yes, wavelength in meters - no one's first choice :-)
>
> -- 
>
> Patrick Dowler
> Canadian Astronomy Data Centre
> National Research Council Canada
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