International Astronomical Union
The International Astronomical Union (IAU) is the governing body for astronomy, and it is the IAU who sets the standards to which our publications adhere.
HMNAO participate in IAU Division A, and in particular Commission 4—Ephemerides. At present staff of HMNAO are members of the IAU Working Groups on Numerical Standards for Fundamental Astronomy, Standardizing Access to Ephemerides, and Standards of Fundamental Astronomy (SOFA). As part of these activities HMNAO manages and hosts the following web sites.
Commission 4 acts as a focus for the exchange of information on ephemerides and standards. It is one of the oldest Commissions and it is the commission to which most of the other almanac producing countries also participate.
The IAU SOFA service establishes and maintains an accessible and authoritative set of algorithms and procedures that implement standard models used in fundamental astronomy.