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The SpecFrame Model

As for a SkyFrame, a SpecFrame is a Frame ([*]) and also a Mapping ([*]), so it inherits all the properties and behaviour of these two ancestral classes. When used as a Mapping, a SpecFrame implements a unit transformation, exactly like a basic Frame ([*]) or a UnitMap, so this aspect of its behaviour is not of great importance.

When used as a Frame, however, a SpecFrame represents a wide range of different 1-dimensional coordinate system which can be used to describe positions within a spectrum. The options available largely mirror those described in the FITS-WCS paper III Representations of spectral coordinates in FITS (Greisen, Valdes, Calabretta & Allen).


next up previous 264
Next: Creating a SpecFrame
Up: Spectral Coordinate Systems (SpecFrames)
Previous: Spectral Coordinate Systems (SpecFrames)

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