leapseconds revision 136638
1136638Swollman# @(#)leapseconds 7.17 275267Swollman 32742Swollman# Allowance for leapseconds added to each timezone file. 42742Swollman 52742Swollman# The International Earth Rotation Service periodically uses leap seconds 658787Sru# to keep UTC to within 0.9 s of UT1 758787Sru# (which measures the true angular orientation of the earth in space); see 82742Swollman# Terry J Quinn, The BIPM and the accurate measure of time, 92742Swollman# Proc IEEE 79, 7 (July 1991), 894-905. 102742Swollman# There were no leap seconds before 1972, because the official mechanism 112742Swollman# accounting for the discrepancy between atomic time and the earth's rotation 122742Swollman# did not exist until the early 1970s. 132742Swollman 142742Swollman# The correction (+ or -) is made at the given time, so lines 152742Swollman# will typically look like: 162742Swollman# Leap YEAR MON DAY 23:59:60 + R/S 172742Swollman# or 182742Swollman# Leap YEAR MON DAY 23:59:59 - R/S 192742Swollman 202742Swollman# If the leapsecond is Rolling (R) the given time is local time 2143014Swollman# If the leapsecond is Stationary (S) the given time is UTC 222742Swollman 232742Swollman# Leap YEAR MONTH DAY HH:MM:SS CORR R/S 242742SwollmanLeap 1972 Jun 30 23:59:60 + S 252742SwollmanLeap 1972 Dec 31 23:59:60 + S 262742SwollmanLeap 1973 Dec 31 23:59:60 + S 272742SwollmanLeap 1974 Dec 31 23:59:60 + S 282742SwollmanLeap 1975 Dec 31 23:59:60 + S 292742SwollmanLeap 1976 Dec 31 23:59:60 + S 302742SwollmanLeap 1977 Dec 31 23:59:60 + S 312742SwollmanLeap 1978 Dec 31 23:59:60 + S 322742SwollmanLeap 1979 Dec 31 23:59:60 + S 332742SwollmanLeap 1981 Jun 30 23:59:60 + S 342742SwollmanLeap 1982 Jun 30 23:59:60 + S 352742SwollmanLeap 1983 Jun 30 23:59:60 + S 362742SwollmanLeap 1985 Jun 30 23:59:60 + S 372742SwollmanLeap 1987 Dec 31 23:59:60 + S 382742SwollmanLeap 1989 Dec 31 23:59:60 + S 392742SwollmanLeap 1990 Dec 31 23:59:60 + S 402742SwollmanLeap 1992 Jun 30 23:59:60 + S 412742SwollmanLeap 1993 Jun 30 23:59:60 + S 422742SwollmanLeap 1994 Jun 30 23:59:60 + S 4339871SphkLeap 1995 Dec 31 23:59:60 + S 4439871SphkLeap 1997 Jun 30 23:59:60 + S 4539898SphkLeap 1998 Dec 31 23:59:60 + S 4686222Swollman 47136638Swollman# INTERNATIONAL EARTH ROTATION AND REFERENCE SYSTEMS SERVICE (IERS) 4875267Swollman# 49136638Swollman# SERVICE INTERNATIONAL DE LA ROTATION TERRESTRE ET DES SYSTEMES DE REFERENCE 50136638Swollman# 5175267Swollman# SERVICE DE LA ROTATION TERRESTRE 5275267Swollman# OBSERVATOIRE DE PARIS 5375267Swollman# 61, Av. de l'Observatoire 75014 PARIS (France) 5475267Swollman# Tel. : 33 (0) 1 40 51 22 26 5575267Swollman# FAX : 33 (0) 1 40 51 22 91 56136638Swollman# Internet : services.iers@obspm.fr 5775267Swollman# 58136638Swollman# Paris, 15 January 2004 5975267Swollman# 60136638Swollman# Bulletin C 27 6175267Swollman# 62121098Swollman# To authorities responsible 63121098Swollman# for the measurement and 64121098Swollman# distribution of time 6575267Swollman# 66121098Swollman# INFORMATION ON UTC - TAI 6775267Swollman# 68136638Swollman# NO positive leap second will be introduced at the end of June 2004. 69121098Swollman# The difference between UTC and the International Atomic Time TAI is: 7086222Swollman# 71136638Swollman# from 1999 January 1, 0h UTC, until further notice : UTC-TAI = -32 s 72136638Swollman# 7393799Swollman# Leap seconds can be introduced in UTC at the end of the months of December 74121098Swollman# or June, depending on the evolution of UT1-TAI. Bulletin C is mailed every 7593799Swollman# six months, either to announce a time step in UTC, or to confirm that there 7693799Swollman# will be no time step at the next possible date. 7786222Swollman# 78121098Swollman# Daniel GAMBIS 79121098Swollman# Director 80121098Swollman# Earth Orientation Center of IERS 81136638Swollman# Observatoire de Paris, France 82