xref: /freebsd/contrib/tzdata/leapseconds (revision 2f02600abfddfc4e9f20dd384a2e729b451e16bd)
1# <pre>
2# This file is in the public domain, so clarified as of
3# 2009-05-17 by Arthur David Olson.
4
5# Allowance for leapseconds added to each timezone file.
6
7# The International Earth Rotation Service periodically uses leap seconds
8# to keep UTC to within 0.9 s of UT1
9# (which measures the true angular orientation of the earth in space); see
10# Terry J Quinn, The BIPM and the accurate measure of time,
11# Proc IEEE 79, 7 (July 1991), 894-905.
12# There were no leap seconds before 1972, because the official mechanism
13# accounting for the discrepancy between atomic time and the earth's rotation
14# did not exist until the early 1970s.
15
16# The correction (+ or -) is made at the given time, so lines
17# will typically look like:
18#	Leap	YEAR	MON	DAY	23:59:60	+	R/S
19# or
20#	Leap	YEAR	MON	DAY	23:59:59	-	R/S
21
22# If the leapsecond is Rolling (R) the given time is local time
23# If the leapsecond is Stationary (S) the given time is UTC
24
25# Leap	YEAR	MONTH	DAY	HH:MM:SS	CORR	R/S
26Leap	1972	Jun	30	23:59:60	+	S
27Leap	1972	Dec	31	23:59:60	+	S
28Leap	1973	Dec	31	23:59:60	+	S
29Leap	1974	Dec	31	23:59:60	+	S
30Leap	1975	Dec	31	23:59:60	+	S
31Leap	1976	Dec	31	23:59:60	+	S
32Leap	1977	Dec	31	23:59:60	+	S
33Leap	1978	Dec	31	23:59:60	+	S
34Leap	1979	Dec	31	23:59:60	+	S
35Leap	1981	Jun	30	23:59:60	+	S
36Leap	1982	Jun	30	23:59:60	+	S
37Leap	1983	Jun	30	23:59:60	+	S
38Leap	1985	Jun	30	23:59:60	+	S
39Leap	1987	Dec	31	23:59:60	+	S
40Leap	1989	Dec	31	23:59:60	+	S
41Leap	1990	Dec	31	23:59:60	+	S
42Leap	1992	Jun	30	23:59:60	+	S
43Leap	1993	Jun	30	23:59:60	+	S
44Leap	1994	Jun	30	23:59:60	+	S
45Leap	1995	Dec	31	23:59:60	+	S
46Leap	1997	Jun	30	23:59:60	+	S
47Leap	1998	Dec	31	23:59:60	+	S
48Leap	2005	Dec	31	23:59:60	+	S
49Leap	2008	Dec	31	23:59:60	+	S
50Leap	2012	Jun	30	23:59:60	+	S
51
52# INTERNATIONAL EARTH ROTATION AND REFERENCE SYSTEMS SERVICE (IERS)
53#
54# SERVICE INTERNATIONAL DE LA ROTATION TERRESTRE ET DES SYSTEMES DE REFERENCE
55#
56#
57# SERVICE DE LA ROTATION TERRESTRE
58# OBSERVATOIRE DE PARIS
59# 61, Av. de l'Observatoire 75014 PARIS (France)
60# Tel.      : 33 (0) 1 40 51 22 26
61# FAX       : 33 (0) 1 40 51 22 91
62# e-mail    : (E-Mail Removed)
63# http://hpiers.obspm.fr/eop-pc
64#
65# Paris, 5 January 2012
66#
67#
68# Bulletin C 43
69#
70# To authorities responsible
71# for the measurement and
72# distribution of time
73#
74#
75# UTC TIME STEP
76# on the 1st of July 2012
77#
78#
79# A positive leap second will be introduced at the end of June 2012.
80# The sequence of dates of the UTC second markers will be:
81#
82#                          2012 June 30,     23h 59m 59s
83#                          2012 June 30,     23h 59m 60s
84#                          2012 July  1,      0h  0m  0s
85#
86# The difference between UTC and the International Atomic Time TAI is:
87#
88# from 2009 January 1, 0h UTC, to 2012 July 1  0h UTC  : UTC-TAI = - 34s
89# from 2012 July 1,    0h UTC, until further notice    : UTC-TAI = - 35s
90#
91# Leap seconds can be introduced in UTC at the end of the months of December
92# or June, depending on the evolution of UT1-TAI. Bulletin C is mailed every
93# six months, either to announce a time step in UTC or to confirm that there
94# will be no time step at the next possible date.
95#
96#
97# Daniel GAMBIS
98# Head
99# Earth Orientation Center of IERS
100# Observatoire de Paris, France
101