units symbols
Arnold Rots
arots at head.cfa.harvard.edu
Fri Oct 5 07:17:03 PDT 2007
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>
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