Observed values of UT1-TAI, 1962-1999

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 2 units of the last digit listed.
________________________________________________________________________________

  Date      UT1-TAI   Date     UT1-TAI    Date     UT1-TAI     Date     UT1-TAI
              (s)                (s)                 (s)                  (s)
________________________________________________________________________________

1962 JAN 1  -1.813  1972 JAN 1 -10.045  1982 JAN 1 -19.983   1992 JAN 1 -26.1252
     APR 1  -1.936       APR 1 -10.347       APR 1 -20.184        APR 1 -26.3562
     JUL 1  -2.058       JUL 1 -10.638       JUL 1 -20.391        JUL 1 -26.5569
     OCT 1  -2.142       OCT 1 -10.888       OCT 1 -20.550        OCT 1 -26.7146

1963 JAN 1  -2.289  1973 JAN 1 -11.189  1983 JAN 1 -20.773   1993 JAN 1 -26.9378
     APR 1  -2.407       APR 1 -11.489       APR 1 -21.036        APR 1 -27.1734
     JUL 1  -2.551       JUL 1 -11.771       JUL 1 -21.250        JUL 1 -27.4010
     OCT 1  -2.659       OCT 1 -12.016       OCT 1 -21.400        OCT 1 -27.5748

1964 JAN 1  -2.847  1974 JAN 1 -12.301  1984 JAN 1 -21.6042  1994 JAN 1 -27.8004
     APR 1  -3.043       APR 1 -12.553       APR 1 -21.7603       APR 1 -28.0202
     JUL 1  -3.217       JUL 1 -12.814       JUL 1 -21.9018       JUL 1 -28.2171
     OCT 1  -3.350       OCT 1 -13.023       OCT 1 -22.0074       OCT 1 -28.3738

1965 JAN 1  -3.558  1975 JAN 1 -13.292  1985 JAN 1 -22.1587  1995 JAN 1 -28.6014
     APR 1  -3.761       APR 1 -13.554       APR 1 -22.3058       APR 1 -28.8437
     JUL 1  -3.964       JUL 1 -13.799       JUL 1 -22.4516       JUL 1 -29.0614
     OCT 1  -4.139       OCT 1 -13.999       OCT 1 -22.5333       OCT 1 -29.2196

1966 JAN 1  -4.360  1976 JAN 1 -14.274  1986 JAN 1 -22.6872  1996 JAN 1 -29.4447
     APR 1  -4.586       APR 1 -14.545       APR 1 -22.8157       APR 1 -29.6292
     JUL 1  -4.817       JUL 1 -14.812       JUL 1 -22.9292       JUL 1 -29.8129
     OCT 1  -5.006       OCT 1 -15.054       OCT 1 -23.0058       OCT 1 -29.9362

1967 JAN 1  -5.248  1977 JAN 1 -15.336  1987 JAN 1 -23.1382  1997 JAN 1 -30.1110
     APR 1  -5.476       APR 1 -15.595       APR 1 -23.2788       APR 1 -30.2914
     JUL 1  -5.700       JUL 1 -15.850       JUL 1 -23.3972       JUL 1 -30.4731
     OCT 1  -5.871       OCT 1 -16.062       OCT 1 -23.4816       OCT 1 -30.6087

1968 JAN 1  -6.111  1978 JAN 1 -16.351  1988 JAN 1 -23.6356  1998 JAN 1 -30.7818
     APR 1  -6.344       APR 1 -16.651       APR 1 -23.7823       APR 1 -30.9622
     JUL 1  -6.573       JUL 1 -16.917       JUL 1 -23.9100       JUL 1 -31.1004
     OCT 1  -6.775       OCT 1 -17.123       OCT 1 -23.9771       OCT 1 -31.1582    

1969 JAN 1  -7.021  1979 JAN 1 -17.402  1989 JAN 1 -24.1159  1999 JAN 1 -31.2833
     APR 1  -7.274       APR 1 -17.670       APR 1 -24.2443       APR 1 -31.3840
     JUL 1  -7.521       JUL 1 -17.918       JUL 1 -24.3857       JUL 1 -31.4801
     OCT 1  -7.734       OCT 1 -18.112       OCT 1 -24.4899

1970 JAN 1  -7.997  1980 JAN 1 -18.355  1990 JAN 1 -24.6713
     APR 1  -8.271       APR 1 -18.582       APR 1 -24.8631
     JUL 1  -8.526       JUL 1 -18.792       JUL 1 -25.0386
     OCT 1  -8.722       OCT 1 -18.970       OCT 1 -25.1803 

1971 JAN 1  -8.985  1981 JAN 1 -19.196  1991 JAN 1 -25.3813 
     APR 1  -9.237       APR 1 -19.414       APR 1 -25.5871
     JUL 1  -9.503       JUL 1 -19.629       JUL 1 -25.7735
     OCT 1  -9.741       OCT 1 -19.777       OCT 1 -25.9204
Created: 1 Jan 2001. Table provided by the former Central Bureau.

IERS HOME ORGANIZATION DATA / PRODUCTS PUBLICATIONS SCIENCE BACKGROUND NEWS / MEETINGS LINKS