next up previous 264
Next: SpecMap - Sequence of spectral coordinate conversions
Up: AST Class Descriptions
Previous: SpecFluxFrame - Compound spectrum/flux Frame


SpecFrame - Spectral coordinate system description

Description:
A SpecFrame is a specialised form of one-dimensional Frame which represents various coordinate systems used to describe positions within an electro-magnetic spectrum. The particular coordinate system to be used is specified by setting the SpecFrame'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.

Constructor Function:
AST_SPECFRAME
Inheritance
The SpecFrame class inherits from the Frame class.
Attributes
In addition to those attributes common to all Frames, every SpecFrame also has the following attributes:

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, "Unit" is allowed in place of "Unit(1)".
Functions
In addition to those routines applicable to all Frames, the following routines may also be applied to all SpecFrames:



next up previous 264
Next: SpecMap - Sequence of spectral coordinate conversions
Up: AST Class Descriptions
Previous: SpecFluxFrame - Compound spectrum/flux Frame

AST A Library for Handling World Coordinate Systems in Astronomy
Starlink User Note 210
R.F. Warren-Smith & D.S. Berry
24th May 2011
E-mail:ussc@star.rl.ac.uk

Copyright (C) 2009 Science \& Technology Facilities Council