Standards of Fundamental Astronomy

The International Astronomical Union's SOFA service has the task of establishing and maintaining an accessible and authoritative set of algorithms and procedures that implement standard models used in fundamental astronomy. The service is managed by an international panel, the SOFA Board, appointed through IAU Division A — Fundamental Astronomy. SOFA also works closely with the International Earth Rotation and Reference Systems Service (IERS).

IAU SOFA Center

This website provides access to the SOFA Software Collection which is currently available for both Fortran 77 and ANSI C. Information on how to obtain it and instructions for its use are available by following the link to current software below.

Using SOFA software is free of charge under the terms and conditions of the SOFA licence.

Long exposure photo of a starry night sky showing star trails radiating from a central point.

Download the latest release

  • Fortran 77

    The latest release from 2023-10-11 is available.

    A night sky filled with stars and the Milky Way galaxy over a lake with a tree in the foreground and mountains in the background.
  • ANSI C

    The latest release from 2023-10-11 is available.

    View of Earth from space with a spacecraft in the upper right corner.
  • Summary of changes

    A summary of changes for the latest release is available.

    Night sky with stars, a shooting star, and a colorful sunset horizon.