timezone/leapseconds

   1 # @(#)leapseconds       8.1
   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 Leap    2005    Dec     31      23:59:60        +       S
  47
  48 #       INTERNATIONAL EARTH ROTATION AND REFERENCE SYSTEMS SERVICE (IERS)
  49 #
  50 # SERVICE INTERNATIONAL DE LA ROTATION TERRESTRE ET DES SYSTEMES DE REFERENCE
  51 #
  52 # SERVICE DE LA ROTATION TERRESTRE
  53 # OBSERVATOIRE DE PARIS
  54 # 61, Av. de l'Observatoire 75014 PARIS (France)
  55 # Tel.      : 33 (0) 1 40 51 22 26
  56 # FAX       : 33 (0) 1 40 51 22 91
  57 # ...
  58 # http://hpiers.obspm.fr/eop-pc
  59 #
  60 #                                               Paris, 4 July 2005
  61 #
  62 #                                               Bulletin C 30
  63 #
  64 #                                               To authorities responsible
  65 #                                               for the measurement and
  66 #                                               distribution of time
  67 #
  68 #
  69 #                                    UTC TIME STEP
  70 #                             on the 1st of January 2006
  71 #
  72 # A positive leap second will be introduced at the end of December 2005.
  73 # The sequence of dates of the UTC second markers will be:
  74 #
  75 #                       2005 December 31,     23h 59m 59s
  76 #                       2005 December 31,     23h 59m 60s
  77 #                       2006 January   1,      0h  0m  0s
  78 #
  79 # The difference between UTC and the International Atomic Time TAI is:
  80 #
  81 # from 1999 January 1, 0h UTC, to 2006 January 1  0h UTC  : UTC-TAI = - 32s
  82 # from 2006 January 1, 0h UTC, until further notice       : UTC-TAI = - 33s
  83 #
  84 # Leap seconds can be introduced in UtC at the end of the months of December
  85 # or June, depending on the evolution of UT1-TAI. Bulletin C is mailed every
  86 # six months, either to announce a time step in UTC or to confirm that there
  87 # will be no time step at the next possible date.
  88 #
  89 #                                       Daniel GAMBIS
  90 #                                       Head
  91 #                                       Earth Orientation Center of IERS
  92 #                                       Observatoire de Paris, France