leapseconds revision 192886
1192886Sedwin# <pre> 2192886Sedwin# @(#)leapseconds 8.8 3192886Sedwin# This file is in the public domain, so clarified as of 4192886Sedwin# 2009-05-17 by Arthur David Olson. 575267Swollman 62742Swollman# Allowance for leapseconds added to each timezone file. 72742Swollman 82742Swollman# The International Earth Rotation Service periodically uses leap seconds 958787Sru# to keep UTC to within 0.9 s of UT1 1058787Sru# (which measures the true angular orientation of the earth in space); see 112742Swollman# Terry J Quinn, The BIPM and the accurate measure of time, 122742Swollman# Proc IEEE 79, 7 (July 1991), 894-905. 132742Swollman# There were no leap seconds before 1972, because the official mechanism 142742Swollman# accounting for the discrepancy between atomic time and the earth's rotation 152742Swollman# did not exist until the early 1970s. 162742Swollman 172742Swollman# The correction (+ or -) is made at the given time, so lines 182742Swollman# will typically look like: 192742Swollman# Leap YEAR MON DAY 23:59:60 + R/S 202742Swollman# or 212742Swollman# Leap YEAR MON DAY 23:59:59 - R/S 222742Swollman 232742Swollman# If the leapsecond is Rolling (R) the given time is local time 2443014Swollman# If the leapsecond is Stationary (S) the given time is UTC 252742Swollman 262742Swollman# Leap YEAR MONTH DAY HH:MM:SS CORR R/S 272742SwollmanLeap 1972 Jun 30 23:59:60 + S 282742SwollmanLeap 1972 Dec 31 23:59:60 + S 292742SwollmanLeap 1973 Dec 31 23:59:60 + S 302742SwollmanLeap 1974 Dec 31 23:59:60 + S 312742SwollmanLeap 1975 Dec 31 23:59:60 + S 322742SwollmanLeap 1976 Dec 31 23:59:60 + S 332742SwollmanLeap 1977 Dec 31 23:59:60 + S 342742SwollmanLeap 1978 Dec 31 23:59:60 + S 352742SwollmanLeap 1979 Dec 31 23:59:60 + S 362742SwollmanLeap 1981 Jun 30 23:59:60 + S 372742SwollmanLeap 1982 Jun 30 23:59:60 + S 382742SwollmanLeap 1983 Jun 30 23:59:60 + S 392742SwollmanLeap 1985 Jun 30 23:59:60 + S 402742SwollmanLeap 1987 Dec 31 23:59:60 + S 412742SwollmanLeap 1989 Dec 31 23:59:60 + S 422742SwollmanLeap 1990 Dec 31 23:59:60 + S 432742SwollmanLeap 1992 Jun 30 23:59:60 + S 442742SwollmanLeap 1993 Jun 30 23:59:60 + S 452742SwollmanLeap 1994 Jun 30 23:59:60 + S 4639871SphkLeap 1995 Dec 31 23:59:60 + S 4739871SphkLeap 1997 Jun 30 23:59:60 + S 4839898SphkLeap 1998 Dec 31 23:59:60 + S 49147771SphkLeap 2005 Dec 31 23:59:60 + S 50181424SedwinLeap 2008 Dec 31 23:59:60 + S 5186222Swollman 52171948Sedwin# INTERNATIONAL EARTH ROTATION AND REFERENCE SYSTEMS SERVICE (IERS) 53176974Sedwin# 54136638Swollman# SERVICE INTERNATIONAL DE LA ROTATION TERRESTRE ET DES SYSTEMES DE REFERENCE 55149514Swollman# 5675267Swollman# SERVICE DE LA ROTATION TERRESTRE 57181424Sedwin# OBSERVATOIRE DE PARIS 5875267Swollman# 61, Av. de l'Observatoire 75014 PARIS (France) 59171948Sedwin# Tel. : 33 (0) 1 40 51 22 26 60171948Sedwin# FAX : 33 (0) 1 40 51 22 91 61181424Sedwin# e-mail : services.iers@obspm.fr 62181424Sedwin# http://hpiers.obspm.fr/eop-pc 63149514Swollman# 64187524Sphk# Paris, 15 January 2009 65149514Swollman# 66187524Sphk# Bulletin C 37 67149514Swollman# 68181424Sedwin# To authorities responsible 69171948Sedwin# for the measurement and 70181424Sedwin# distribution of time 71171948Sedwin# 72187524Sphk# NO positive leap second will be introduced at the end of June 2009. 73187524Sphk# The difference between Coordinated Universal Time UTC and the 74187524Sphk# International Atomic Time TAI is : 75187524Sphk# 76187524Sphk# from 2009 January 1, 0h UTC, until further notice : UTC-TAI = -34 s 77171948Sedwin# 78171948Sedwin# Leap seconds can be introduced in UTC at the end of the months of December 79181424Sedwin# or June, depending on the evolution of UT1-TAI. Bulletin C is mailed every 80181424Sedwin# six months, either to announce a time step in UTC or to confirm that there 81171948Sedwin# will be no time step at the next possible date. 82171948Sedwin# 83171948Sedwin# Daniel GAMBIS 84181424Sedwin# Head 85181424Sedwin# Earth Orientation Center of IERS 86171948Sedwin# Observatoire de Paris, France 87