astSkyOffsetMapastSkyOffsetMap - Returns a Mapping which goes from absolute coordinates to offset coordinates

Description:
This function returns a MappingMapping in which the forward transformation transforms a position in the coordinate system given by the SystemSystem attribute of the supplied SkyFrameSkyFrame, into the offset coordinate system specified by the SkyRef, SkyRefP and SkyRefIsSkyRefIs attributes of the supplied SkyFrame.

A UnitMapUnitMap is returned if the SkyFrame does not define an offset coordinate system.

Synopsis:
AstMapping $*$astSkyOffsetMap( AstSkyFrame $*$this )
Parameters:
this
Pointer to the SkyFrame.
Returned Value:
astSkyOffsetMap()
Pointer to the returned Mapping.
Notes:
  • A null ObjectObject pointer (AST__NULL) will be returned if this function is invoked with the AST error status set, or if it should fail for any reason.