leapseconds revision 140320
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 4775267Swollman# 48140320Swollman# 49140320Swollman# 50140320Swollman# INTERNATIONAL EARTH ROTATION AND REFERENCE SYSTEMS SERVICE (IERS) 51140320Swollman# 52136638Swollman# SERVICE INTERNATIONAL DE LA ROTATION TERRESTRE ET DES SYSTEMES DE REFERENCE 53136638Swollman# 5475267Swollman# SERVICE DE LA ROTATION TERRESTRE 55140320Swollman# OBSERVATOIRE DE PARIS 5675267Swollman# 61, Av. de l'Observatoire 75014 PARIS (France) 5775267Swollman# Tel. : 33 (0) 1 40 51 22 26 5875267Swollman# FAX : 33 (0) 1 40 51 22 91 59136638Swollman# Internet : services.iers@obspm.fr 6075267Swollman# 61140320Swollman# Paris, 14 January 2005 62140320Swollman# 6375267Swollman# 64140320Swollman# Bulletin C 29 65140320Swollman# 66140320Swollman# To authorities responsible 67140320Swollman# for the measurement and 68140320Swollman# distribution of time 69140320Swollman# 7075267Swollman# 7175267Swollman# 72140320Swollman# INFORMATION ON UTC - TAI 73140320Swollman# 7475267Swollman# 75140320Swollman# NO positive leap second will be introduced at the end of June 2005. 76140320Swollman# The difference between Coordinated Universal Time UTC and the 77140320Swollman# International Atomic Time TAI is : 78140320Swollman# 79140320Swollman# from 1999 January 1, 0h UTC, until further notice : UTC-TAI = -32 s 8086222Swollman# 81140320Swollman# Leap seconds can be introduced in UTC at the end of the months of December 82140320Swollman# or June, depending on the evolution of UT1-TAI. Bulletin C is mailed every 83140320Swollman# six months, either to announce a time step in UTC, or to confirm that there 84140320Swollman# will be no time step at the next possible date. 85136638Swollman# 8686222Swollman# 87140320Swollman# Daniel GAMBIS 88140320Swollman# Director 89140320Swollman# Earth Orientation Center of IERS 90140320Swollman# Observatoire de Paris, France 91140320Swollman# 92