A TimeMap is a specialised form of 1-dimensional Mapping which can be used to represent a sequence of conversions between standard time coordinate systems.
When a TimeMap is first created, it simply performs a unit (null) Mapping. Using the AST_TIMEADD routine, a series of coordinate conversion steps may then be added. This allows multi-step conversions between a variety of time coordinate systems to be assembled out of a set of building blocks.
For details of the individual coordinate conversions available, see the description of the AST_TIMEADD routine.
The nature and units of the coordinate values supplied for the first input (i.e. the time input) of a
TimeMap must be appropriate to the first conversion step applied by the TimeMap. For instance, if the
first conversion step is
" (Modified Julian Date to Besselian epoch) then the coordinate
values for the first input should be date in units of days. Similarly, the nature and units of the
coordinate values returned by a TimeMap will be determined by the last conversion step applied by
A null Object pointer (AST__NULL) will be returned if this function is invoked with STATUS set to an error value, or if it should fail for any reason.