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Developing Standards

Information concerning developing standards and those under consideration for update.


 Masses of Ceres and Vesta

Possible update of gravity field (mass) of Ceres and Vesta based on Dawn results. See Konopliv, A. S., et al., Icarus, 299, p. 411-429: "The Ceres gravity field, spin pole, rotation period and orbit from the Dawn radiometric tracking and optical data"


 Mean Pole

The International Earth Rotation and Reference Systems Service (IERS) is currently (2017 September) discussing the name Mean Pole, in order to decide a name that better reflects the situation. This plot of polar motion (from the IERS), shows mean pole displacement from 1900 to 2006.


 Time Scales

Following the meeting in June 2017, the Consultative Committee for Time and Frequency (CCTF) has asked the CIPM to consider their Recommendation on the definition of time-scales for adoption.

The purpose of this recommendation is to remove the ambiguity between TT and International Atomic Time (TAI) by making the definition of TAI conform to the constant LG defining the rate of TT.



The next generation of the International Celestial Reference Frame — ICRF3 — was adopted by the IAU at the XXX IAU General Assembly in August 2018 as the fundamental reference frame by Resolution B2, and took effect on 1 January 2019.

The data for ICRF3 sources and it's description are available on the IERS site. A paper detailing the steps taken in constructing the ICRF3 formulation from

Patrick Charlot, the chair of the ICRF3 working group (WG) is currently in preparation and forthcoming.

Last modified: 2020 April