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CIPM, 1956: Resolution 1
Version française
 
Definition of the unit of time (second)*

In virtue of the powers invested in it by Resolution 5 of the 10th Conférence Générale des Poids et Mesures, the Comité International des Poids et Mesures,

considering

  1. that the 9th General Assembly of the International Astronomical Union (Dublin, 1955) declared itself in favour of linking the second to the tropical year,
  2. that, according to the decisions of the 8th General Assembly of the International Astronomical Union (Rome, 1952), the second of ephemeris time (ET) is the fraction
    (12 960 276 813 / 408 986 496) ´ 10-9 of the tropical year for 1900 January 0 at 12 h ET,

decides "The second is the fraction 1/31 556 925.9747 of the tropical year for 1900 January 0 at 12 hours ephemeris time."



Reference:
Procès-Verbaux des Séances du CIPM (1956), p. 77

Note:

This definition was abrogated in 1967 by the 13th CGPM (Resolution 1).
 
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