Miguel Cervino wrote:
> First I center in "Q" UCDs, and I propose to keep:
>
> Q|em.energy |Energy value in the em frame
> Q|em.freq |Frequency value in the em frame
> Q|em.wavenumber |Wavenumber value in the em frame
> Q|em.wl |Wavelength value in the em frame
The point is that:
1. It would be clearer to use the em branch just to describe the
electro-magnetic axis (radio, ir,opt,...,line,..) and move energy, freq, wl
to the phys branch.
2. We now have phys.energy and em.energy
If you ask the assign tool
http://vizier.u-strasbg.fr/UCD/cgi-bin/descr2ucd
the word energy is translated always into phys.energy : correct.
You only get em.energy if you type photon energy : correct too.
But we are describing the same quantity with two ucd-words!
> Q|em.wl.air* |Wavelength value in the em frame in air frame
>
> somewhere it should be established default is vacuum?
> In most optical observation default is air and
> in UV vacuum as example, but SLOAN data release
> gives optical wl en vacuum...
yes, things are complicated: you often find <laboratory wl> which, I
suspect, are wl.air in the optical and, obviously, wl.vacuum in the UV!
> Q|em.veloc* |Apparent radial velocity
> Q|em.veloc.radio* |radio velocity
> Q|em.veloc.optical* |optical velocity
> Q|em.veloc.beta* |velocity/cr
somebody proposed already velocRadio, velocOpt. I ask him/her to re-submit
that proposal
>
> - Change from Q to E:
> Q|em.wl.central |Central wavelength
> Q|em.wl.effective |Effective wavelength
Yes, with the flag set to Q and a description like: central wl of Halpha
you'll get only wl.central .
> ... for clarity purpose and hogenity
> the UDCs I would suggest the following changues:
>
> em.IR.K --> em.IR.2-3um
> em.IR.H --> em.IR1500-2000nm
> em.IR.J --> em.IR1000-1500nm
>
> em.opt.I --> em.opt.750-1000nm
> em.opt.R --> em.opt.600-750nm
> em.opt.V --> em.opt.500-600nm
> em.opt.B --> em.opt.400-500nm
> em.opt.U --> em.opt.300-400nm
>
> so there no will be confusion with fotometry bands
may be we should go this way, because the names of those bands can be
misleading.
In the case of x- and gamma-rays though there is no confusion, so I would
keep the existing names...
> Finally, I think that the inclusion of em.line would be useful, but
> only for a very sort list of lines so ... I would agree with
> Hydrogen lines, but I do think that em.line.OIII should be
> depreciated (there is several OIII lines!, and if OIII is here, by
> not, O I, or H+K Ca II etc...? so I propose depreciate em.line.OIII ...
the reason for the inclusion of the OIII line is that the doublet 4959+5007
is one of the strongest lines in emission-line objects (second only to
Halpha in most cases). There are surveys in Halpha/beta and in OIII, not in
OI.
My point is: today em.line.OIII is used/useful. The day we'll find other
lines useful we'll propose their inclusion.
By the way: em.line.XXX is not a quantity: it is a qualifier of some other
quantity, e.g. intensity, flux, etc..
Cheers
Andrea Received on 2005-06-10Z11:00:44