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The leap second was introduced in 1972. Since then, 27 leap seconds have been added to UTC, with the most recent occurring on December 31, 2016. [1] All have so far been positive leap seconds, adding a second to a UTC day; while it is possible for a negative leap second to be needed, one has not happened yet.
- Leap Seconds
- Current UT1-UTC Values
- Dut1 Corrections
Coordinated Universal Time (UTC) is based on International Atomic Time (TAI), but it is adjusted by leap seconds to account for the difference between the definition of the second and the rotation of Earth. This correction keeps UTC in conjunction with the apparent position of the Sun and the stars, and it is the standard used for all general timek...
This table lists the most recent differences between UT1 and UTC. This information is obtained from the United States Naval Observatory (USNO). Weekly UT1-UTC Values
Leap seconds ensure that UT1 - UTC will always be held within ±0.9 s. The current value of UT1 - UTC is called the DUT1 correction and is obtained from the Bureau International des Poids et Mesures (BIPM). DUT1 corrections are broadcast by WWV, WWVH, WWVB and ACTS, and are printed below. These corrections may be added to received UTC time signals i...
Negative Leap Seconds. Leap seconds can be positive (1 second added to the schedule) or negative (1 second omitted). So far, all leap seconds have been positive. However, if the Earth's rotation keeps accelerating, as it has done in 2020, the IERS may decide to announce the world's first negative leap second at some point in the future. Days ...
Sep 16, 2024 · So far, there have only been positive leap seconds. However, there is a provision for negative leap seconds if it becomes necessary due to changes in Earth's rotation. The designation of the sequence to remove a second would be: 23h 59m 57s 23h 59m 58s 00h 00m 00s (the beginning of the following date)
The table below lists all leap seconds that have already occurred, or are scheduled to occur. All leap seconds listed in the table are positive leap seconds, which means an extra second is inserted into the UTC time scale. The sequence of events is: 23h 59m 59s - 23h 59m 60s - 00h 00m 00s. NOTE: No leap second will be added at the end of ...
Jun 24, 2022 · 3,124,137,601. Table 1. NTP Leap Second Numbering. While the last second of a normal day is 23:59:59, the last second of a leap day is 23:59:60. Since this makes the day one second longer than the usual day, the day rollover will not occur until the end of the first occurrence of second 3,124,137,600.
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Why do we add a leap second every 3 years?
The first leap second occurred in 1972, and now in mid 2023, UTC is 37 seconds behind TAI. Adding a leap second every three years is only necessary if Earth spins at a rate such that 86,400.001 SI (TAI) seconds fit into a mean solar day. In the 1960s, Earth entered a period in which its spin slowed strongly, so that by the mid 1970s, a mean ...
