dm: Re: units symbols

From: Arnold Rots <arots-at-head.cfa.harvard.edu>
Date: Fri, 5 Oct 2007 10:17:03 -0400 (EDT)

I caught on to the units somewhat belatedly, but here are the unit strings that are currently allowed in STC (XSD excerpt is appended).

Time unit strings:

  's' (second)
  'h' (hour = 3600 s)
  'd' (day = 86400 s)
  'a' or 'yr' (Julian year = 365.25 d)
  'cy' (Julian century = 36525 d)
  '' (empty, i.e., dimensionless; for ISO-8601 format)

Spatial coordinate unit strings:
  angular
'deg' (degree)
'rad' (radian)
'h' (hour)
'arcmin'
'arcsec'

  linear
'm' (meter)
'km'
'mm'
'AU'
'pc' (parsec)
'kpc'
'Mpc'
'lyr' (lightyear)
'' (empty, i.e., dimensionless, for unit sphere)
  three-units strings are for special 3-D vectors where the components   do not share the same unit; one may prefer to give each component   its own unit, instead:
'deg deg m'
'deg deg Mpc'

  Then there is the position angle definition (not strictly a unit):     Position angles may be counted from North (through East),     (positive) X (to positive Y),
    or (positive) Y (to positive X) axis

      'North'
      'X'
      'Y'

velocity units are constructed as posUnitType / velTimeType the latter may be second, day, hour, year (a or yr), century, but not empty

Spectral units:
  frequency
'Hz'
'kHz'
'MHz'
'GHz'

  wavelength
'm'
'mm'
'um' (micron)
'nm'
'Angstrom'

  energy
'eV'
'keV'
'MeV'
'GeV'
'TeV'

Arnold

Anita M. S. Richards wrote:
[ Charset UTF-8 unsupported, converting... ]

> 
> Thanks very much Jesus,
> 
> The VOSpec model will be very useful.
> 
> Please can I ask anyone with important information or comments, especially 
> references to useful documents, to put them on the wiki page
> 
> http://www.ivoa.net/twiki/bin/view/IVOA/UnitsDesc
> 
> thanks
> 
> Anita
> 
> - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
> 
> Dr. A.M.S. Richards, AstroGrid Astronomer, University of Manchester, 
> Jodrell Bank Centre for Astrophysics, Turing Building, 
> University of Manchester, M13 9PL
> +44 (0)161 275 4124
> and
> MERLIN/VLBI National Facility, Jodrell Bank Observatory, 
> Cheshire SK11 9DL, U.K. +44 (0)1477 571321 (tel) 571618 (fax)
> 
> 
> On Thu, 4 Oct 2007, Jesus Salgado wrote:
> 
--------------------------------------------------------------------------
Arnold H. Rots                                Chandra X-ray Science Center
Smithsonian Astrophysical Observatory                tel:  +1 617 496 7701
60 Garden Street, MS 67                              fax:  +1 617 495 7356
Cambridge, MA 02138                             arots-at-head.cfa.harvard.edu
USA                                     http://hea-www.harvard.edu/~arots/
--------------------------------------------------------------------------

  <xs:simpleType name="timeUnitType">
    <xs:annotation>
      <xs:documentation>Time units may be second (s), hour (h: 3600 s), day (d: 86400 s), Julian year (a, yr: 365.25 d), Julian century (cy: 36525 d), or empty (i.e., dimensionless) for ISO-8601 format</xs:documentation>     </xs:annotation>
    <xs:restriction base="unitType">

      <xs:enumeration value="s"/>
      <xs:enumeration value="h"/>
      <xs:enumeration value="d"/>
      <xs:enumeration value="a"/>
      <xs:enumeration value="yr"/>
      <xs:enumeration value="cy"/>
      <xs:enumeration value=""/>

    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="posUnitType">
    <xs:annotation>
      <xs:documentation>Spatial coordinate units may be angular (degrees, radians, hours, arcmins, arcsecs), linear (meters, km, mm, AUs, parsecs, kpc, Mpc, lightyears), or empty (i.e., dimensionless). The three-units strings are for special 3-D vectors where the components do not share the same unit; one may prefer to give each component its own unit, instead.</xs:documentation>     </xs:annotation>
    <xs:restriction base="unitType">

      <xs:enumeration value="deg"/>
      <xs:enumeration value="deg deg m"/>
      <xs:enumeration value="deg deg Mpc"/>
      <xs:enumeration value="rad"/>
      <xs:enumeration value="h"/>
      <xs:enumeration value="arcmin"/>
      <xs:enumeration value="arcsec"/>
      <xs:enumeration value="m"/>
      <xs:enumeration value="km"/>
      <xs:enumeration value="mm"/>
      <xs:enumeration value="AU"/>
      <xs:enumeration value="pc"/>
      <xs:enumeration value="kpc"/>
      <xs:enumeration value="Mpc"/>
      <xs:enumeration value="lyr"/>
      <xs:enumeration value=""/>

    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="angleUnitType">
    <xs:annotation>
      <xs:documentation>Angular coordinate units may be degrees, radians, hours, arcmins, arcsecs</xs:documentation>     </xs:annotation>
    <xs:restriction base="unitType">

      <xs:enumeration value="deg"/>
      <xs:enumeration value="rad"/>
      <xs:enumeration value="h"/>
      <xs:enumeration value="arcmin"/>
      <xs:enumeration value="arcsec"/>

    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="posAngleReferenceType">     <xs:annotation>
      <xs:documentation>Position angles may be counted from North (through East), (positive) X (to positive Y), or (positive) Y (to positive X) axis</xs:documentation>     </xs:annotation>
    <xs:restriction base="xs:string">

      <xs:enumeration value="North"/>
      <xs:enumeration value="X"/>
      <xs:enumeration value="Y"/>

    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="velTimeUnitType">     <xs:annotation>
      <xs:documentation>Velocity units are a posUnitType / velTimeType; the latter may be second, day, hour, year (a or yr), century, but not empty</xs:documentation>     </xs:annotation>
    <xs:restriction base="unitType">

      <xs:enumeration value="s"/>
      <xs:enumeration value="h"/>
      <xs:enumeration value="d"/>
      <xs:enumeration value="a"/>
      <xs:enumeration value="yr"/>
      <xs:enumeration value="cy"/>

    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="spectralUnitType">     <xs:annotation>
      <xs:documentation>Spectral units may be frequency (Hz, kHz, MHz, GHz), wavelength (meters, mm, micron, nm, Angstrom), or energy (eV, keV, MeV, GeV, TeV)</xs:documentation>     </xs:annotation>
    <xs:restriction base="unitType">

      <xs:enumeration value="Hz"/>
      <xs:enumeration value="kHz"/>
      <xs:enumeration value="MHz"/>
      <xs:enumeration value="GHz"/>
      <xs:enumeration value="m"/>
      <xs:enumeration value="mm"/>
      <xs:enumeration value="um"/>
      <xs:enumeration value="nm"/>
      <xs:enumeration value="Angstrom"/>
      <xs:enumeration value="eV"/>
      <xs:enumeration value="keV"/>
      <xs:enumeration value="MeV"/>
      <xs:enumeration value="GeV"/>
      <xs:enumeration value="TeV"/>

</xs:restriction>
</xs:simpleType> Received on 2007-10-05Z16:17:38