Developing Standards

This page will contains links and information concerning various developing standards. Those at the top of the list with the red square are current.

 

 W₀, the Potential of the Geoid

The International Association of Geodesy (IAG), as part of the realization of the International Height Reference System (IHRS), passed in 2015 a resolution providing a new best estimate of W₀.

This parameter does not affect any IAU definitions, constants or standard parameters, since any parameters that did involve W₀ have already been modified (e.g. IAU 2000 definition of Terrestrial Time (TT)), also, see Time Scales below.

 

 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 L_G defining the rate of TT.