xref: /freebsd-10.2-release/contrib/tzdata/leapseconds

# @(#)leapseconds	8.6

# 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
Leap	2008	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
# e-mail    : services.iers@obspm.fr
# http://hpiers.obspm.fr/eop-pc
#
# Paris, 4 July 2008
#
# Bulletin C 36
#
# To authorities responsible
# for the measurement and
# distribution of time
#
# UTC TIME STEP
# on the 1st of January 2009
#
# A positive leap second will be introduced at the end of December 2008.
# The sequence of dates of the UTC second markers will be:		
#
# 2008 December 31,     23h 59m 59s
# 2008 December 31,     23h 59m 60s
# 2009 January   1,      0h  0m  0s
#
# The difference between UTC and the International Atomic Time TAI is:
#
# from 2006 January 1, 0h UTC, to 2009 January 1  0h UTC  : UTC-TAI = - 33s
# from 2009 January 1, 0h UTC, until further notice       : UTC-TAI = - 34s
#
# 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