Leap Second Table

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The Leap Second Table (UTCTAI.dat file) is an editable ASCII text file that contains historical and predicted occurrences of leap seconds. It is based on historical data provided by The US Naval Observatory and predicted data provided by Goddard Space Flight Center.

 

FreeFlyer will add 9 seconds to any date before the first epoch or row in the table (11317.5 - Jan 1, 1972), and then will add a single leap second based on the epoch that is in the first column of the UTCTAI.dat file.

 

Predicted and definitive leap second occurrences can be found on the USNO web site: http://maia.usno.navy.mil/. Since the Leap Second Table is an ASCII text file, it can easily be edited by simply adding the time of the leap second (in UTC Julian (GSFC)) and a comment (for user benefit).

 

The format of the file is shown below.

11317.5         // January 1, 1972

11499.5         // July    1, 1972

11683.5         // January 1, 1973

12048.5         // January 1, 1974

12413.5         // January 1, 1975

12778.5         // January 1, 1976

13144.5         // January 1, 1977

13509.5         // January 1, 1978

13874.5         // January 1, 1979

14239.5         // January 1, 1980

14786.5         // July    1, 1981

15151.5         // July    1, 1982

15516.5         // July    1, 1983

16247.5         // July    1, 1985

17161.5         // January 1, 1988

17892.5         // January 1, 1990

18257.5         // January 1, 1991

18804.5         // July    1, 1992

19169.5         // July    1, 1993

19534.5         // July    1, 1994

20083.5         // January 1, 1996

20630.5         // July    1, 1997

21179.5         // January 1, 1999

23736.5         // January 1, 2006

24832.5         // January 1, 2009

26109.5         // July    1, 2012

27204.5         // July    1, 2015

27754.5         // January 1, 2017