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Merge pull request #42 from alcoat/main
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update leap-seconds.txt
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fbriol authored Jan 19, 2025
2 parents e8482a6 + dfad04a commit bc25859
Showing 1 changed file with 15 additions and 15 deletions.
30 changes: 15 additions & 15 deletions src/python/pyfes/data/leap-seconds.txt
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# ATOMIC TIME.
# The Coordinated Universal Time (UTC) is the reference time scale derived
# ATOMIC TIME
# Coordinated Universal Time (UTC) is the reference time scale derived
# from The "Temps Atomique International" (TAI) calculated by the Bureau
# International des Poids et Mesures (BIPM) using a worldwide network of atomic
# clocks. UTC differs from TAI by an integer number of seconds; it is the basis
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#
# ASTRONOMICAL TIME (UT1) is the time scale based on the rate of rotation of the earth.
# It is now mainly derived from Very Long Baseline Interferometry (VLBI). The various
# irregular fluctuations progressively detected in the rotation rate of the Earth lead
# irregular fluctuations progressively detected in the rotation rate of the Earth led
# in 1972 to the replacement of UT1 by UTC as the reference time scale.
#
#
# LEAP SECOND
# Atomic clocks are more stable than the rate of the earth rotation since the latter
# Atomic clocks are more stable than the rate of the earth's rotation since the latter
# undergoes a full range of geophysical perturbations at various time scales: lunisolar
# and core-mantle torques, atmospheric and oceanic effetcs, etc.
# and core-mantle torques, atmospheric and oceanic effects, etc.
# Leap seconds are needed to keep the two time scales in agreement, i.e. UT1-UTC smaller
# than 0.9 second. Therefore, when necessary a "leap second" is applied to UTC.
# than 0.9 seconds. Therefore, when necessary a "leap second" is applied to UTC.
# Since the adoption of this system in 1972 it has been necessary to add a number of seconds to UTC,
# firstly due to the initial choice of the value of the second (1/86400 mean solar day of
# the year 1820) and secondly to the general slowing down of the Earth's rotation. It is
# theorically possible to have a negative leap second (a second removed from UTC), but so far,
# theoretically possible to have a negative leap second (a second removed from UTC), but so far,
# all leap seconds have been positive (a second has been added to UTC). Based on what we know about
# the earth's rotation, it is unlikely that we will ever have a negative leap second.
#
#
# HISTORY
# The first leap second was added on June 30, 1972. Until yhe year 2000, it was necessary in average to add a
# The first leap second was added on June 30, 1972. Until the year 2000, it was necessary in average to add a
# leap second at a rate of 1 to 2 years. Since the year 2000 leap seconds are introduced with an
# average interval of 3 to 4 years due to the acceleration of the Earth rotation speed.
# average interval of 3 to 4 years due to the acceleration of the Earth's rotation speed.
#
#
# RESPONSABILITY OF THE DECISION TO INTRODUCE A LEAP SECOND IN UTC
# RESPONSIBILITY OF THE DECISION TO INTRODUCE A LEAP SECOND IN UTC
# The decision to introduce a leap second in UTC is the responsibility of the Earth Orientation Center of
# the International Earth Rotation and reference System Service (IERS). This center is located at Paris
# Observatory. According to international agreements, leap seconds should only be scheduled for certain dates:
# Observatory. According to international agreements, leap seconds should be scheduled only for certain dates:
# first preference is given to the end of December and June, and second preference at the end of March
# and September. Since the introduction of leap seconds in 1972, only dates in June and December were used.
#
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#
# The following line shows the last update of this file in NTP timestamp:
#
#$ 3913697179
#$ 3945196800
#
# 2) Expiration date of the file given on a semi-annual basis: last June or last December
#
# File expires on 28 December 2024
# File expires on 28 December 2025
#
# Expire date in NTP timestamp:
#
#@ 3944332800
#@ 3975868800
#
#
# LIST OF LEAP SECONDS
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# please see the readme file in the 'source' directory :
# https://hpiers.obspm.fr/iers/bul/bulc/ntp/sources/README
#
#h 9dac5845 8acd32c0 2947d462 daf4a943 f58d9391
#h 848434d5 570f7ea8 d79ba227 a00fc821 f608e2d4

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