leapseconds revision 136638
1156608Sdeischen# @(#)leapseconds 7.17 2156608Sdeischen 3156608Sdeischen# Allowance for leapseconds added to each timezone file. 4156608Sdeischen 5156608Sdeischen# The International Earth Rotation Service periodically uses leap seconds 6156608Sdeischen# to keep UTC to within 0.9 s of UT1 7156608Sdeischen# (which measures the true angular orientation of the earth in space); see 8156608Sdeischen# Terry J Quinn, The BIPM and the accurate measure of time, 9156608Sdeischen# Proc IEEE 79, 7 (July 1991), 894-905. 10156608Sdeischen# There were no leap seconds before 1972, because the official mechanism 11156608Sdeischen# accounting for the discrepancy between atomic time and the earth's rotation 12156608Sdeischen# did not exist until the early 1970s. 13156608Sdeischen 14# The correction (+ or -) is made at the given time, so lines 15# will typically look like: 16# Leap YEAR MON DAY 23:59:60 + R/S 17# or 18# Leap YEAR MON DAY 23:59:59 - R/S 19 20# If the leapsecond is Rolling (R) the given time is local time 21# If the leapsecond is Stationary (S) the given time is UTC 22 23# Leap YEAR MONTH DAY HH:MM:SS CORR R/S 24Leap 1972 Jun 30 23:59:60 + S 25Leap 1972 Dec 31 23:59:60 + S 26Leap 1973 Dec 31 23:59:60 + S 27Leap 1974 Dec 31 23:59:60 + S 28Leap 1975 Dec 31 23:59:60 + S 29Leap 1976 Dec 31 23:59:60 + S 30Leap 1977 Dec 31 23:59:60 + S 31Leap 1978 Dec 31 23:59:60 + S 32Leap 1979 Dec 31 23:59:60 + S 33Leap 1981 Jun 30 23:59:60 + S 34Leap 1982 Jun 30 23:59:60 + S 35Leap 1983 Jun 30 23:59:60 + S 36Leap 1985 Jun 30 23:59:60 + S 37Leap 1987 Dec 31 23:59:60 + S 38Leap 1989 Dec 31 23:59:60 + S 39Leap 1990 Dec 31 23:59:60 + S 40Leap 1992 Jun 30 23:59:60 + S 41Leap 1993 Jun 30 23:59:60 + S 42Leap 1994 Jun 30 23:59:60 + S 43Leap 1995 Dec 31 23:59:60 + S 44Leap 1997 Jun 30 23:59:60 + S 45Leap 1998 Dec 31 23:59:60 + S 46 47# INTERNATIONAL EARTH ROTATION AND REFERENCE SYSTEMS SERVICE (IERS) 48# 49# SERVICE INTERNATIONAL DE LA ROTATION TERRESTRE ET DES SYSTEMES DE REFERENCE 50# 51# SERVICE DE LA ROTATION TERRESTRE 52# OBSERVATOIRE DE PARIS 53# 61, Av. de l'Observatoire 75014 PARIS (France) 54# Tel. : 33 (0) 1 40 51 22 26 55# FAX : 33 (0) 1 40 51 22 91 56# Internet : services.iers@obspm.fr 57# 58# Paris, 15 January 2004 59# 60# Bulletin C 27 61# 62# To authorities responsible 63# for the measurement and 64# distribution of time 65# 66# INFORMATION ON UTC - TAI 67# 68# NO positive leap second will be introduced at the end of June 2004. 69# The difference between UTC and the International Atomic Time TAI is: 70# 71# from 1999 January 1, 0h UTC, until further notice : UTC-TAI = -32 s 72# 73# Leap seconds can be introduced in UTC at the end of the months of December 74# or June, depending on the evolution of UT1-TAI. Bulletin C is mailed every 75# six months, either to announce a time step in UTC, or to confirm that there 76# will be no time step at the next possible date. 77# 78# Daniel GAMBIS 79# Director 80# Earth Orientation Center of IERS 81# Observatoire de Paris, France 82