# @(#)leapseconds       8.1

# Allowance for leapseconds added to each timezone file.

# The International Earth Rotation Service periodically uses leap seconds
# to keep UTC to within 0.9 s of UT1
# (which measures the true angular orientation of the earth in space); see
# Terry J Quinn, The BIPM and the accurate measure of time,
# Proc IEEE 79, 7 (July 1991), 894-905.
# There were no leap seconds before 1972, because the official mechanism
# accounting for the discrepancy between atomic time and the earth's rotation
# did not exist until the early 1970s.

# The correction (+ or -) is made at the given time, so lines
# will typically look like:
#       Leap    YEAR    MON     DAY     23:59:60        +       R/S
# or
#       Leap    YEAR    MON     DAY     23:59:59        -       R/S

# If the leapsecond is Rolling (R) the given time is local time
# If the leapsecond is Stationary (S) the given time is UTC

# Leap  YEAR    MONTH   DAY     HH:MM:SS        CORR    R/S
Leap    1972    Jun     30      23:59:60        +       S
Leap    1972    Dec     31      23:59:60        +       S
Leap    1973    Dec     31      23:59:60        +       S
Leap    1974    Dec     31      23:59:60        +       S
Leap    1975    Dec     31      23:59:60        +       S
Leap    1976    Dec     31      23:59:60        +       S
Leap    1977    Dec     31      23:59:60        +       S
Leap    1978    Dec     31      23:59:60        +       S
Leap    1979    Dec     31      23:59:60        +       S
Leap    1981    Jun     30      23:59:60        +       S
Leap    1982    Jun     30      23:59:60        +       S
Leap    1983    Jun     30      23:59:60        +       S
Leap    1985    Jun     30      23:59:60        +       S
Leap    1987    Dec     31      23:59:60        +       S
Leap    1989    Dec     31      23:59:60        +       S
Leap    1990    Dec     31      23:59:60        +       S
Leap    1992    Jun     30      23:59:60        +       S
Leap    1993    Jun     30      23:59:60        +       S
Leap    1994    Jun     30      23:59:60        +       S
Leap    1995    Dec     31      23:59:60        +       S
Leap    1997    Jun     30      23:59:60        +       S
Leap    1998    Dec     31      23:59:60        +       S
Leap    2005    Dec     31      23:59:60        +       S

#       INTERNATIONAL EARTH ROTATION AND REFERENCE SYSTEMS SERVICE (IERS)
#
# SERVICE INTERNATIONAL DE LA ROTATION TERRESTRE ET DES SYSTEMES DE REFERENCE
#
# SERVICE DE LA ROTATION TERRESTRE
# OBSERVATOIRE DE PARIS
# 61, Av. de l'Observatoire 75014 PARIS (France)
# Tel.      : 33 (0) 1 40 51 22 26
# FAX       : 33 (0) 1 40 51 22 91
# ...
# http://hpiers.obspm.fr/eop-pc
#
#                                               Paris, 4 July 2005
#                                                       
#                                               Bulletin C 30
#
#                                               To authorities responsible
#                                               for the measurement and
#                                               distribution of time
#
#
#                                    UTC TIME STEP
#                             on the 1st of January 2006
#
# A positive leap second will be introduced at the end of December 2005.
# The sequence of dates of the UTC second markers will be:
#
#                       2005 December 31,     23h 59m 59s
#                       2005 December 31,     23h 59m 60s
#                       2006 January   1,      0h  0m  0s
#
# The difference between UTC and the International Atomic Time TAI is:
#
# from 1999 January 1, 0h UTC, to 2006 January 1  0h UTC  : UTC-TAI = - 32s
# from 2006 January 1, 0h UTC, until further notice       : UTC-TAI = - 33s
#
# Leap seconds can be introduced in UtC at the end of the months of December
# or June, depending on the evolution of UT1-TAI. Bulletin C is mailed every
# six months, either to announce a time step in UTC or to confirm that there
# will be no time step at the next possible date.
#
#                                       Daniel GAMBIS
#                                       Head
#                                       Earth Orientation Center of IERS
#                                       Observatoire de Paris, France
