24 # Allowance for leap seconds added to each time zone file. |
24 # Allowance for leap seconds added to each time zone file. |
25 |
25 |
26 # This file is in the public domain. |
26 # This file is in the public domain. |
27 |
27 |
28 # This file is generated automatically from the data in the public-domain |
28 # This file is generated automatically from the data in the public-domain |
29 # leap-seconds.list file, which can be copied from |
29 # NIST format leap-seconds.list file, which can be copied from |
30 # <ftp://ftp.nist.gov/pub/time/leap-seconds.list> |
30 # <ftp://ftp.nist.gov/pub/time/leap-seconds.list> |
31 # or <ftp://ftp.boulder.nist.gov/pub/time/leap-seconds.list> |
31 # or <ftp://ftp.boulder.nist.gov/pub/time/leap-seconds.list>. |
32 # or <ftp://tycho.usno.navy.mil/pub/ntp/leap-seconds.list>. |
|
33 # For more about leap-seconds.list, please see |
32 # For more about leap-seconds.list, please see |
34 # The NTP Timescale and Leap Seconds |
33 # The NTP Timescale and Leap Seconds |
35 # <https://www.eecis.udel.edu/~mills/leap.html>. |
34 # <https://www.eecis.udel.edu/~mills/leap.html>. |
36 |
35 |
37 # The International Earth Rotation and Reference Systems Service |
36 # The rules for leap seconds are specified in Annex 1 (Time scales) of: |
|
37 # Standard-frequency and time-signal emissions. |
|
38 # International Telecommunication Union - Radiocommunication Sector |
|
39 # (ITU-R) Recommendation TF.460-6 (02/2002) |
|
40 # <https://www.itu.int/rec/R-REC-TF.460-6-200202-I/>. |
|
41 # The International Earth Rotation and Reference Systems Service (IERS) |
38 # periodically uses leap seconds to keep UTC to within 0.9 s of UT1 |
42 # periodically uses leap seconds to keep UTC to within 0.9 s of UT1 |
39 # (which measures the true angular orientation of the earth in space) |
43 # (a proxy for Earth's angle in space as measured by astronomers) |
40 # and publishes leap second data in a copyrighted file |
44 # and publishes leap second data in a copyrighted file |
41 # <https://hpiers.obspm.fr/iers/bul/bulc/Leap_Second.dat>. |
45 # <https://hpiers.obspm.fr/iers/bul/bulc/Leap_Second.dat>. |
42 # See: Levine J. Coordinated Universal Time and the leap second. |
46 # See: Levine J. Coordinated Universal Time and the leap second. |
43 # URSI Radio Sci Bull. 2016;89(4):30-6. doi:10.23919/URSIRSB.2016.7909995 |
47 # URSI Radio Sci Bull. 2016;89(4):30-6. doi:10.23919/URSIRSB.2016.7909995 |
44 # <https://ieeexplore.ieee.org/document/7909995>. |
48 # <https://ieeexplore.ieee.org/document/7909995>. |
45 |
49 |
46 # There were no leap seconds before 1972, because the official mechanism |
50 # There were no leap seconds before 1972, as no official mechanism |
47 # accounting for the discrepancy between atomic time and the earth's rotation |
51 # accounted for the discrepancy between atomic time (TAI) and the earth's |
48 # did not exist. The first ("1 Jan 1972") data line in leap-seconds.list |
52 # rotation. The first ("1 Jan 1972") data line in leap-seconds.list |
49 # does not denote a leap second; it denotes the start of the current definition |
53 # does not denote a leap second; it denotes the start of the current definition |
50 # of UTC. |
54 # of UTC. |
51 |
55 |
52 # The correction (+ or -) is made at the given time, so lines |
56 # All leap-seconds are Stationary (S) at the given UTC time. |
53 # will typically look like: |
57 # The correction (+ or -) is made at the given time, so in the unlikely |
54 # Leap YEAR MON DAY 23:59:60 + R/S |
58 # event of a negative leap second, a line would look like this: |
55 # or |
59 # Leap YEAR MON DAY 23:59:59 - S |
56 # Leap YEAR MON DAY 23:59:59 - R/S |
60 # Typical lines look like this: |
57 |
61 # Leap YEAR MON DAY 23:59:60 + S |
58 # If the leap second is Rolling (R) the given time is local time (unused here). |
|
59 Leap 1972 Jun 30 23:59:60 + S |
62 Leap 1972 Jun 30 23:59:60 + S |
60 Leap 1972 Dec 31 23:59:60 + S |
63 Leap 1972 Dec 31 23:59:60 + S |
61 Leap 1973 Dec 31 23:59:60 + S |
64 Leap 1973 Dec 31 23:59:60 + S |
62 Leap 1974 Dec 31 23:59:60 + S |
65 Leap 1974 Dec 31 23:59:60 + S |
63 Leap 1975 Dec 31 23:59:60 + S |
66 Leap 1975 Dec 31 23:59:60 + S |