TT2UT1:

-------------------------------------------------------------------------------
   Converts TT (Terrestrial (dynamic) Time)
   to UT1 (time scale based on the rotation of the earth)
   UT1 = TT - DT where DT is determined from astronomical
   observations.
-------------------------------------------------------------------------------
   Form:
   jDUT1 = TT2UT1( jDTT )
-------------------------------------------------------------------------------

   ------
   Inputs
   ------
   jDTT      (1,1) Julian date Terrestrial (Dynamic) Time

   -------
   Outputs
   -------
   jDUT1     (1,1) ulian date Universal Time 1

-------------------------------------------------------------------------------

Children:

Common: Time/DeltaT