xref: /freebsd/contrib/tzdata/leapseconds (revision 0f2bd1e89db1a2f09268edea21e0ead329e092df)
1# <pre>
2# @(#)leapseconds	8.10
3# This file is in the public domain, so clarified as of
4# 2009-05-17 by Arthur David Olson.
5
6# Allowance for leapseconds added to each timezone file.
7
8# The International Earth Rotation Service periodically uses leap seconds
9# to keep UTC to within 0.9 s of UT1
10# (which measures the true angular orientation of the earth in space); see
11# Terry J Quinn, The BIPM and the accurate measure of time,
12# Proc IEEE 79, 7 (July 1991), 894-905.
13# There were no leap seconds before 1972, because the official mechanism
14# accounting for the discrepancy between atomic time and the earth's rotation
15# did not exist until the early 1970s.
16
17# The correction (+ or -) is made at the given time, so lines
18# will typically look like:
19#	Leap	YEAR	MON	DAY	23:59:60	+	R/S
20# or
21#	Leap	YEAR	MON	DAY	23:59:59	-	R/S
22
23# If the leapsecond is Rolling (R) the given time is local time
24# If the leapsecond is Stationary (S) the given time is UTC
25
26# Leap	YEAR	MONTH	DAY	HH:MM:SS	CORR	R/S
27Leap	1972	Jun	30	23:59:60	+	S
28Leap	1972	Dec	31	23:59:60	+	S
29Leap	1973	Dec	31	23:59:60	+	S
30Leap	1974	Dec	31	23:59:60	+	S
31Leap	1975	Dec	31	23:59:60	+	S
32Leap	1976	Dec	31	23:59:60	+	S
33Leap	1977	Dec	31	23:59:60	+	S
34Leap	1978	Dec	31	23:59:60	+	S
35Leap	1979	Dec	31	23:59:60	+	S
36Leap	1981	Jun	30	23:59:60	+	S
37Leap	1982	Jun	30	23:59:60	+	S
38Leap	1983	Jun	30	23:59:60	+	S
39Leap	1985	Jun	30	23:59:60	+	S
40Leap	1987	Dec	31	23:59:60	+	S
41Leap	1989	Dec	31	23:59:60	+	S
42Leap	1990	Dec	31	23:59:60	+	S
43Leap	1992	Jun	30	23:59:60	+	S
44Leap	1993	Jun	30	23:59:60	+	S
45Leap	1994	Jun	30	23:59:60	+	S
46Leap	1995	Dec	31	23:59:60	+	S
47Leap	1997	Jun	30	23:59:60	+	S
48Leap	1998	Dec	31	23:59:60	+	S
49Leap	2005	Dec	31	23:59:60	+	S
50Leap	2008	Dec	31	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# SERVICE DE LA ROTATION TERRESTRE
57# OBSERVATOIRE DE PARIS
58# 61, Av. de l'Observatoire 75014 PARIS (France)
59# Tel.      : 33 (0) 1 40 51 22 26
60# FAX       : 33 (0) 1 40 51 22 91
61# Internet  : services.iers@obspm.fr
62#
63# Paris, 14 July 2010
64#
65# Bulletin C 40
66#
67# To authorities responsible
68# for the measurement and
69# distribution of time
70#
71# INFORMATION ON UTC - TAI
72#
73# NO positive leap second will be introduced at the end of December 2010.
74# The difference between Coordinated Universal Time UTC and the
75# International Atomic Time TAI is :
76#
77# from 2009 January 1, 0h UTC, until further notice : UTC-TAI = -34 s
78#
79# Leap seconds can be introduced in UTC at the end of the months of December
80# or June,  depending on the evolution of UT1-TAI. Bulletin C is mailed every
81# six months, either to announce a time step in UTC, or to confirm that there
82# will be no time step at the next possible date.
83#
84# Daniel GAMBIS
85# Director
86# Earth Orientation Center of IERS
87# Observatoire de Paris, France
88