Skip to content

Main content
Bookmark this: tool.io/geodesy/leap-second-count-since-1972-counter

Leap Second Count Since 1972 Counter

Count actual published positive leap seconds since the 1972 ten-second TAI-UTC baseline using a pinned IERS table; rejects dates before 1972 or beyond its stated expiration.

Loading tool…

Description

Count leap seconds since the 1972 baseline using a pinned, date-bounded IERS table.

Geodesy distinguishes a mathematical reference ellipsoid, a realized coordinate datum and the physical gravity field. Geodetic latitude follows the ellipsoid normal; geocentric latitude follows a radius from the center. Ellipsoidal height, orthometric height and geoid undulation are separate signed quantities. Keep the declared ellipsoid, coordinate axes, angular units and time scale with a result.

Count leap seconds since the 1972 baseline using a pinned, date-bounded IERS table.

The checked IERS table lists TAI−UTC steps from the ten-second 1972 baseline and states an expiry of 28 June 2027. This tool uses an embedded snapshot rather than downloading a current table.1

When to use this tool

Use this tool when you need to count leap seconds since the 1972 baseline using a pinned, date-bounded IERS table.

How to use the tool and how it works

  1. Enter utcDate using the definitions below.
  2. Run the operation. Resolve input-format errors before interpreting an output.
  3. Read result.leapSecondsSince1972, result.taiMinusUtcSeconds, result.reference, using the stated boundary, ordering, sign and absence conventions.

Parse the supplied UTC date at midnight and look up TAI−UTC in the embedded step table. Subtract the initial 1972 offset of ten seconds to obtain leap seconds introduced since 1972.2

Input fieldMeaning and unitsAccepted input
utcDateExact Gregorian YYYY-MM-DD UTC date at midnight within the pinned leap-table interval.Text, at most 8,192 UTF-16 code units; narrower grammar/range rules also apply.
Output fieldInterpretation
resultObject containing the fields below.
result.leapSecondsSince1972Pinned table TAI−UTC minus the initial ten-second 1972 offset.
result.taiMinusUtcSecondsPinned table TAI−UTC step in seconds at the requested date.
result.referenceName/validity note for the pinned table or rounded reference constant.
json
{
  "input": {
    "utcDate": "2017-01-01"
  },
  "output": {
    "result": {
      "leapSecondsSince1972": 27,
      "taiMinusUtcSeconds": 37,
      "reference": "IERS Bulletin C 72, valid before 2027-06-28"
    }
  }
}

Limitations and assumptions

  • Only dates from 1972-01-01 through 2027-06-27 are accepted by this pinned table. It includes the step effective 2017-01-01 and cites Bulletin C 72; it neither fetches updates nor establishes future UTC policy. Leap-second timestamps themselves are not parsed.
  • All quantities are finite and retain the units stated for this operation. Ellipsoid-parameter tools use semi-major axis 1–10⁸ m and dimensionless flattening 0–0.02; explicit-axis tools use 0.9a≤b≤a unless a tighter bound is stated. These tools do not fetch datums, geoid grids, satellite observations or Earth-orientation updates.
  • Every declared outer field is required and unknown outer fields are rejected. Strings and JSON text have size limits, lists are bounded to 128 entries, and JSON nesting/node counts are bounded. Tighter operation-specific bounds stated above take precedence.
  • Numeric results must be finite. Large physical magnitudes are allowed by the output evidence checks, while integer fields and source schemas retain their exactness rules. Source indexes are zero-based. Floating-point residues can remain even where an ideal formula gives an exact zero.

Alternative or Complementary methods

Use a coordinate transform for a change of representation and explicit datum parameters for a change of reference frame. Preserve model and convergence metadata, and use observation and datum information appropriate to a real survey before interpreting a computed tolerance as accuracy.

References

  1. TAI−UTC step table, updated through Bulletin C 72 — IERS Earth Orientation Centre

  2. Tool behavior and example: Leap Second Count Since 1972 Counter — tool.io

Similar or alternative tools

Support Tool.io