Formal sets of constants, along with recommended values, have been defined by the International Astronomical Union (IAU) several times: in 1964[1] and in 1976[2] (with an update in 1994[3]).
In 2009 the IAU adopted a new current set, and recognizing that new observations and techniques continuously provide better values for these constants, they decided[4] to not fix these values, but have the Working Group on Numerical Standards continuously maintain a set of Current Best Estimates.
Besides the IAU list of units and constants, also the International Earth Rotation and Reference Systems Service defines constants relevant to the orientation and rotation of the Earth, in its technical notes.
Slightly different values for the constants are obtained depending on the frame of reference used.
The values here are appropriate for the older theories, but additional constants are required for current models.