IDL> es = 0.0
IDL> cdf_tt2000, epoch, 2000,1,1,0,0,0, /comp
IDL> print, (es-epoch/1.d+9) - 3600.*12
      -64.184000

IDL> es = 31622400.000000
IDL> cdf_tt2000, epoch, 2001,1,1,0,0,0, /comp
IDL> print, (es-epoch/1.d+9) - 3600.*12
      -64.184000

IDL> es =504921604.000000
IDL> cdf_tt2000, epoch, 2016,1,1,0,0,0, /comp
IDL> print, (es-epoch/1.d+9) - 3600.*12
      -68.184000

IDL> es =536544005.000000
IDL> cdf_tt2000, epoch, 2017,1,1,0,0,0, /comp
IDL> print, (es-epoch/1.d+9) - 3600.*12
      -69.184000
IDL>