" Standards
of Rest" section (below).
The default StdOfRest value is " Helio" .
" Topocentric" , " Topocent" or " Topo" : The observers rest-frame (assumed to be on the surface of the
earth). Spectra recorded in this standard of rest suffer a Doppler shift which varies over the course of a
day because of the rotation of the observer around the axis of the earth. This standard
of rest must be qualified using the ObsLat, ObsLon, ObsAlt, Epoch, RefRA and RefDec
attributes.
" Geocentric" , " Geocentr" or " Geo" : The rest-frame of the earth centre. Spectra recorded in this
standard of rest suffer a Doppler shift which varies over the course of a year because of the rotation of
the earth around the Sun. This standard of rest must be qualified using the Epoch, RefRA and RefDec
attributes.
" Barycentric" , " Barycent" or " Bary" : The rest-frame of the solar-system barycentre. Spectra
recorded in this standard of rest suffer a Doppler shift which depends both on the velocity of the
Sun through the Local Standard of Rest, and on the movement of the planets through the
solar system. This standard of rest must be qualified using the Epoch, RefRA and RefDec
attributes.
" Heliocentric" , " Heliocen" or " Helio" : The rest-frame of the Sun. Spectra recorded in this standard
of rest suffer a Doppler shift which depends on the velocity of the Sun through the Local
Standard of Rest. This standard of rest must be qualified using the RefRA and RefDec
attributes.
" LSRK" , " LSR" : The rest-frame of the kinematical Local Standard of Rest. Spectra recorded in this
standard of rest suffer a Doppler shift which depends on the velocity of the kinematical Local
Standard of Rest through the galaxy. This standard of rest must be qualified using the RefRA and
RefDec attributes.
" LSRD" : The rest-frame of the dynamical Local Standard of Rest. Spectra recorded in this standard of
rest suffer a Doppler shift which depends on the velocity of the dynamical Local Standard of Rest
through the galaxy. This standard of rest must be qualified using the RefRA and RefDec
attributes.
" Galactic" , " Galactoc" or " Gal" : The rest-frame of the galactic centre. Spectra recorded in this
standard of rest suffer a Doppler shift which depends on the velocity of the galactic centre
through the local group. This standard of rest must be qualified using the RefRA and RefDec
attributes.
" Local_group" , " Localgrp" or " LG" : The rest-frame of the local group. This standard of rest must
be qualified using the RefRA and RefDec attributes.
" Source" , or " src" : The rest-frame of the source. This standard of rest must be qualified using the
RefRA, RefDec and SourceVel attributes.
Where more than one alternative System value is shown above, the first of these will be returned when an enquiry is made.