zic.tproj/datfiles/leapseconds

   1 # @(#)leapseconds       7.17
   2
   3 # Allowance for leapseconds added to each timezone file.
   4
   5 # The International Earth Rotation Service periodically uses leap seconds
   6 # to keep UTC to within 0.9 s of UT1
   7 # (which measures the true angular orientation of the earth in space); see
   8 # Terry J Quinn, The BIPM and the accurate measure of time,
   9 # Proc IEEE 79, 7 (July 1991), 894-905.
  10 # There were no leap seconds before 1972, because the official mechanism
  11 # accounting for the discrepancy between atomic time and the earth's rotation
  12 # did not exist until the early 1970s.
  13
  14 # The correction (+ or -) is made at the given time, so lines
  15 # will typically look like:
  16 #       Leap    YEAR    MON     DAY     23:59:60        +       R/S
  17 # or
  18 #       Leap    YEAR    MON     DAY     23:59:59        -       R/S
  19
  20 # If the leapsecond is Rolling (R) the given time is local time
  21 # If the leapsecond is Stationary (S) the given time is UTC
  22
  23 # Leap  YEAR    MONTH   DAY     HH:MM:SS        CORR    R/S
  24 Leap    1972    Jun     30      23:59:60        +       S
  25 Leap    1972    Dec     31      23:59:60        +       S
  26 Leap    1973    Dec     31      23:59:60        +       S
  27 Leap    1974    Dec     31      23:59:60        +       S
  28 Leap    1975    Dec     31      23:59:60        +       S
  29 Leap    1976    Dec     31      23:59:60        +       S
  30 Leap    1977    Dec     31      23:59:60        +       S
  31 Leap    1978    Dec     31      23:59:60        +       S
  32 Leap    1979    Dec     31      23:59:60        +       S
  33 Leap    1981    Jun     30      23:59:60        +       S
  34 Leap    1982    Jun     30      23:59:60        +       S
  35 Leap    1983    Jun     30      23:59:60        +       S
  36 Leap    1985    Jun     30      23:59:60        +       S
  37 Leap    1987    Dec     31      23:59:60        +       S
  38 Leap    1989    Dec     31      23:59:60        +       S
  39 Leap    1990    Dec     31      23:59:60        +       S
  40 Leap    1992    Jun     30      23:59:60        +       S
  41 Leap    1993    Jun     30      23:59:60        +       S
  42 Leap    1994    Jun     30      23:59:60        +       S
  43 Leap    1995    Dec     31      23:59:60        +       S
  44 Leap    1997    Jun     30      23:59:60        +       S
  45 Leap    1998    Dec     31      23:59:60        +       S
  46
  47 #       INTERNATIONAL EARTH ROTATION AND REFERENCE SYSTEMS SERVICE (IERS)
  48 #
  49 # SERVICE INTERNATIONAL DE LA ROTATION TERRESTRE ET DES SYSTEMES DE REFERENCE
  50 #
  51 # SERVICE DE LA ROTATION TERRESTRE
  52 # OBSERVATOIRE DE PARIS
  53 # 61, Av. de l'Observatoire 75014 PARIS (France)
  54 # Tel.      : 33 (0) 1 40 51 22 26
  55 # FAX       : 33 (0) 1 40 51 22 91
  56 # Internet  : services.iers@obspm.fr
  57 #
  58 #                                               Paris, 15 January 2004
  59 #
  60 #                                               Bulletin C 27
  61 #
  62 #                                               To authorities responsible
  63 #                                               for the measurement and
  64 #                                               distribution of time
  65 #
  66 #                       INFORMATION ON UTC - TAI
  67 #
  68 # NO positive leap second will be introduced at the end of June 2004.
  69 # The difference between UTC and the International Atomic Time TAI is:
  70 #
  71 #       from 1999 January 1, 0h UTC, until further notice : UTC-TAI = -32 s
  72 #
  73 # Leap seconds can be introduced in UTC at the end of the months of December
  74 # or June, depending on the evolution of UT1-TAI. Bulletin C is mailed every
  75 # six months, either to announce a time step in UTC, or to confirm that there
  76 # will be no time step at the next possible date.
  77 #
  78 #                                       Daniel GAMBIS
  79 #                                       Director
  80 #                                       Earth Orientation Center of IERS
  81 #                                       Observatoire de Paris, France