The SpecFrame constructor function is particularly simple and a SpecFrame with default attributes is created as follows:
#include "ast.h" AstSpecFrame *specframe; ... specframe = astSpecFrame( "" );
Such a SpecFrame would represent the default coordinate system which is
heliocentric wavelength in metres (i.e. wavelength corrected to take into
account the Doppler shift caused by the velocity of the observer around the
sun).
AST A Library for Handling World Coordinate Systems in Astronomy