’s System attribute (the default is wavelength) qualified, as necessary, by other attributes such as the rest frequency, the standard of rest, the epoch of observation, units, etc (see the description of the System attribute for details).
By setting a value for thr SpecOrigin attribute, a SpecFrame can be made to represent offsets from a given spectral position, rather than absolute spectral values.
AlignSpecOffset: Align SpecFrames using the offset coordinate system?
AlignStdOfRest: Standard of rest in which to align SpecFrames
RefDec: Declination of the source (FK5 J2000)
RefRA: Right ascension of the source (FK5 J2000)
RestFreq: Rest frequency
SourceSys: Source velocity spectral system
SourceVel: Source velocity
SourceVRF: Source velocity rest frame
SpecOrigin: The zero point for SpecFrame axis values
StdOfRest: Standard of rest
Several of the Frame attributes inherited by the SpecFrame class refer to a specific axis of the Frame
(for instance Unit(axis), Label(axis), etc). Since a SpecFrame is strictly one-dimensional, it allows these
attributes to be specified without an axis index. So for instance,
" is allowed in place of