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OBSERVED VALUES OF UT1-TAI, 1962-2008

TT-UT1 can be obtained from this table using the expression

TT-UT1 = 32.184s - (UT1-TAI)

The uncertainty of UT1-TAI is smaller than 1 unit of the last digit listed.

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  Date      UT1-TAI   Date      UT1-TAI   Date      UT1-TAI    Date      UT1-TAI
              (s)                 (s)                 (s)                  (s)
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1962 JAN 1  -1.813  1974 JAN 1 -12.301  1986 JAN 1 -22.6872  1998 JAN 1 -30.7819
     APR 1  -1.936       APR 1 -12.553       APR 1 -22.8157       APR 1 -30.9622
     JUL 1  -2.058       JUL 1 -12.814       JUL 1 -22.9292       JUL 1 -31.1004
     OCT 1  -2.142       OCT 1 -13.023       OCT 1 -23.0058       OCT 1 -31.1582

1963 JAN 1  -2.289  1975 JAN 1 -13.292  1987 JAN 1 -23.1382  1999 JAN 1 -31.2834
     APR 1  -2.407       APR 1 -13.554       APR 1 -23.2788       APR 1 -31.3839
     JUL 1  -2.551       JUL 1 -13.799       JUL 1 -23.3972       JUL 1 -31.4802
     OCT 1  -2.659       OCT 1 -13.999       OCT 1 -23.4816       OCT 1 -31.5307

1964 JAN 1  -2.847  1976 JAN 1 -14.274  1988 JAN 1 -23.6356  2000 JAN 1 -31.6445
     APR 1  -3.043       APR 1 -14.545       APR 1 -23.7823       APR 1 -31.7235
     JUL 1  -3.217       JUL 1 -14.812       JUL 1 -23.9100       JUL 1 -31.7959
     OCT 1  -3.350       OCT 1 -15.054       OCT 1 -23.9771       OCT 1 -31.8253

1965 JAN 1  -3.558  1977 JAN 1 -15.336  1989 JAN 1 -24.1159  2001 JAN 1 -31.9067
     APR 1  -3.761       APR 1 -15.595       APR 1 -24.2443       APR 1 -31.9745
     JUL 1  -3.964       JUL 1 -15.850       JUL 1 -24.3857       JUL 1 -32.0277
     OCT 1  -4.139       OCT 1 -16.062       OCT 1 -24.4899       OCT 1 -32.0383

1966 JAN 1  -4.360  1978 JAN 1 -16.351  1990 JAN 1 -24.6713  2002 JAN 1 -32.1158
     APR 1  -4.586       APR 1 -16.651       APR 1 -24.8631       APR 1 -32.1895
     JUL 1  -4.817       JUL 1 -16.917       JUL 1 -25.0386       JUL 1 -32.2292
     OCT 1  -5.006       OCT 1 -17.123       OCT 1 -25.1803       OCT 1 -32.2328

1967 JAN 1  -5.248  1979 JAN 1 -17.402  1991 JAN 1 -25.3813  2003 JAN 1 -32.2895
     APR 1  -5.476       APR 1 -17.670       APR 1 -25.5871       APR 1 -32.3429
     JUL 1  -5.700       JUL 1 -17.918       JUL 1 -25.7735       JUL 1 -32.3672
     OCT 1  -5.871       OCT 1 -18.112       OCT 1 -25.9204       OCT 1 -32.3575

1968 JAN 1  -6.111  1980 JAN 1 -18.355  1992 JAN 1 -26.1252  2004 JAN 1 -32.3896
     APR 1  -6.344       APR 1 -18.582       APR 1 -26.3562       APR 1 -32.4336
     JUL 1  -6.573       JUL 1 -18.792       JUL 1 -26.5569       JUL 1 -32.4690
     OCT 1  -6.775       OCT 1 -18.970       OCT 1 -26.7146       OCT 1 -32.4560

1969 JAN 1  -7.021  1981 JAN 1 -19.196  1993 JAN 1 -26.9378  2005 JAN 1 -32.5039
     APR 1  -7.274       APR 1 -19.414       APR 1 -27.1734       APR 1 -32.5735
     JUL 1  -7.521       JUL 1 -19.629       JUL 1 -27.4010       JUL 1 -32.6155
     OCT 1  -7.734       OCT 1 -19.777       OCT 1 -27.5748       OCT 1 -32.6081

1970 JAN 1  -7.997  1982 JAN 1 -19.983  1994 JAN 1 -27.8004  2006 JAN 1 -32.6612
     APR 1  -8.271       APR 1 -20.184       APR 1 -28.0202       APR 1 -32.7335
     JUL 1  -8.526       JUL 1 -20.391       JUL 1 -28.2171       JUL 1 -32.8055        
     OCT 1  -8.722       OCT 1 -20.550       OCT 1 -28.3738       OCT 1 -32.8532          

1971 JAN 1  -8.985  1983 JAN 1 -20.773  1995 JAN 1 -28.6014  2007 JAN 1 -32.9624     
     APR 1  -9.237       APR 1 -21.036       APR 1 -28.8437       APR 1 -33.0654    
     JUL 1  -9.503       JUL 1 -21.250       JUL 1 -29.0614       JUL 1 -33.1574      
     OCT 1  -9.741       OCT 1 -21.400       OCT 1 -29.2196       OCT 1 -33.1871     

1972 JAN 1 -10.045  1984 JAN 1 -21.604  1996 JAN 1 -29.4447  2008 JAN 1 -33.2733     
     APR 1 -10.347       APR 1 -21.760       APR 1 -29.6292       APR 1 -33.3610   
     JUL 1 -10.638       JUL 1 -21.902       JUL 1 -29.8129       JUL 1 -33.4447       
     OCT 1 -10.888       OCT 1 -22.007       OCT 1 -29.9362       OCT 1 -33.4920    

1973 JAN 1 -11.189  1985 JAN 1 -22.159  1997 JAN 1 -30.1110  2009 JAN 1 -33.5896      
     APR 1 -11.489       APR 1 -22.306       APR 1 -30.2914     
     JUL 1 -11.771       JUL 1 -22.452       JUL 1 -30.4731     
     OCT 1 -12.016       OCT 1 -22.533       OCT 1 -30.6086