11315084cSEdwin Groothuis# Allowance for leap seconds added to each time zone file. 21315084cSEdwin Groothuis 3dd53226cSXin LI# This file is in the public domain. 4dd53226cSXin LI 5dd53226cSXin LI# This file is generated automatically from the data in the public-domain 62723c7ffSPhilip Paeps# NIST/IERS format leap-seconds.list file, which can be copied from 7dc505d53SPhilip Paeps# <https://hpiers.obspm.fr/iers/bul/bulc/ntp/leap-seconds.list> 82723c7ffSPhilip Paeps# or, in a variant with different comments, from 92723c7ffSPhilip Paeps# <ftp://ftp.boulder.nist.gov/pub/time/leap-seconds.list>. 10dd53226cSXin LI# For more about leap-seconds.list, please see 11dd53226cSXin LI# The NTP Timescale and Leap Seconds 1289abb9f8SPhilip Paeps# <https://www.eecis.udel.edu/~mills/leap.html>. 13dd53226cSXin LI 14798c0c0bSPhilip Paeps# The rules for leap seconds are specified in Annex 1 (Time scales) of: 15798c0c0bSPhilip Paeps# Standard-frequency and time-signal emissions. 16798c0c0bSPhilip Paeps# International Telecommunication Union - Radiocommunication Sector 17798c0c0bSPhilip Paeps# (ITU-R) Recommendation TF.460-6 (02/2002) 18798c0c0bSPhilip Paeps# <https://www.itu.int/rec/R-REC-TF.460-6-200202-I/>. 19798c0c0bSPhilip Paeps# The International Earth Rotation and Reference Systems Service (IERS) 20dd53226cSXin LI# periodically uses leap seconds to keep UTC to within 0.9 s of UT1 21798c0c0bSPhilip Paeps# (a proxy for Earth's angle in space as measured by astronomers) 2289abb9f8SPhilip Paeps# and publishes leap second data in a copyrighted file 2389abb9f8SPhilip Paeps# <https://hpiers.obspm.fr/iers/bul/bulc/Leap_Second.dat>. 2489abb9f8SPhilip Paeps# See: Levine J. Coordinated Universal Time and the leap second. 258d7edd17SPhilip Paeps# URSI Radio Sci Bull. 2016;89(4):30-6. doi:10.23919/URSIRSB.2016.7909995 2689abb9f8SPhilip Paeps# <https://ieeexplore.ieee.org/document/7909995>. 272c5e84ccSPhilip Paeps 28798c0c0bSPhilip Paeps# There were no leap seconds before 1972, as no official mechanism 29798c0c0bSPhilip Paeps# accounted for the discrepancy between atomic time (TAI) and the earth's 30798c0c0bSPhilip Paeps# rotation. The first ("1 Jan 1972") data line in leap-seconds.list 312c5e84ccSPhilip Paeps# does not denote a leap second; it denotes the start of the current definition 322c5e84ccSPhilip Paeps# of UTC. 331315084cSEdwin Groothuis 34798c0c0bSPhilip Paeps# All leap-seconds are Stationary (S) at the given UTC time. 35798c0c0bSPhilip Paeps# The correction (+ or -) is made at the given time, so in the unlikely 36798c0c0bSPhilip Paeps# event of a negative leap second, a line would look like this: 37798c0c0bSPhilip Paeps# Leap YEAR MON DAY 23:59:59 - S 38798c0c0bSPhilip Paeps# Typical lines look like this: 39798c0c0bSPhilip Paeps# Leap YEAR MON DAY 23:59:60 + S 401315084cSEdwin GroothuisLeap 1972 Jun 30 23:59:60 + S 411315084cSEdwin GroothuisLeap 1972 Dec 31 23:59:60 + S 421315084cSEdwin GroothuisLeap 1973 Dec 31 23:59:60 + S 431315084cSEdwin GroothuisLeap 1974 Dec 31 23:59:60 + S 441315084cSEdwin GroothuisLeap 1975 Dec 31 23:59:60 + S 451315084cSEdwin GroothuisLeap 1976 Dec 31 23:59:60 + S 461315084cSEdwin GroothuisLeap 1977 Dec 31 23:59:60 + S 471315084cSEdwin GroothuisLeap 1978 Dec 31 23:59:60 + S 481315084cSEdwin GroothuisLeap 1979 Dec 31 23:59:60 + S 491315084cSEdwin GroothuisLeap 1981 Jun 30 23:59:60 + S 501315084cSEdwin GroothuisLeap 1982 Jun 30 23:59:60 + S 511315084cSEdwin GroothuisLeap 1983 Jun 30 23:59:60 + S 521315084cSEdwin GroothuisLeap 1985 Jun 30 23:59:60 + S 531315084cSEdwin GroothuisLeap 1987 Dec 31 23:59:60 + S 541315084cSEdwin GroothuisLeap 1989 Dec 31 23:59:60 + S 551315084cSEdwin GroothuisLeap 1990 Dec 31 23:59:60 + S 561315084cSEdwin GroothuisLeap 1992 Jun 30 23:59:60 + S 571315084cSEdwin GroothuisLeap 1993 Jun 30 23:59:60 + S 581315084cSEdwin GroothuisLeap 1994 Jun 30 23:59:60 + S 591315084cSEdwin GroothuisLeap 1995 Dec 31 23:59:60 + S 601315084cSEdwin GroothuisLeap 1997 Jun 30 23:59:60 + S 611315084cSEdwin GroothuisLeap 1998 Dec 31 23:59:60 + S 621315084cSEdwin GroothuisLeap 2005 Dec 31 23:59:60 + S 631315084cSEdwin GroothuisLeap 2008 Dec 31 23:59:60 + S 64aad8a35cSEdwin GroothuisLeap 2012 Jun 30 23:59:60 + S 65dd53226cSXin LILeap 2015 Jun 30 23:59:60 + S 668fdf5721SBaptiste DaroussinLeap 2016 Dec 31 23:59:60 + S 672289da42SEdwin Groothuis 68dd5f96c4SPhilip Paeps# UTC timestamp when this leap second list expires. 69dd5f96c4SPhilip Paeps# Any additional leap seconds will come after this. 70dd5f96c4SPhilip Paeps# This Expires line is commented out for now, 71dd5f96c4SPhilip Paeps# so that pre-2020a zic implementations do not reject this file. 72*46226b01SPhilip Paeps#Expires 2025 Dec 28 00:00:00 73dd5f96c4SPhilip Paeps 7489abb9f8SPhilip Paeps# POSIX timestamps for the data in this file: 75*46226b01SPhilip Paeps#updated 1736208000 (2025-01-07 00:00:00 UTC) 76*46226b01SPhilip Paeps#expires 1766880000 (2025-12-28 00:00:00 UTC) 7789abb9f8SPhilip Paeps 782723c7ffSPhilip Paeps# Updated through IERS Bulletin C (https://hpiers.obspm.fr/iers/bul/bulc/bulletinc.dat) 79*46226b01SPhilip Paeps# File expires on 28 December 2025 80