Standards of Fundamental Astronomy

The Standards of Fundamental Astronomy (SOFA) software libraries are a collection of subroutines that implement official International Astronomical Union (IAU) algorithms for astronomical computations.

Standards of Fundamental Astronomy
Stable release	2023-10-11 / 2023-10-11
Written in	C and Fortran
Operating system	Cross-platform
Type	Numerical library
License	SOFA Software License
Website	http://www.iausofa.org/

As of February 2009 they are available in both Fortran and C source code format.

Capabilities

The subroutines in the libraries cover the following areas:

• Calendars
• Time scales
• Earth's rotation and sidereal time
• Ephemerides (limited precision)
• Precession, nutation, polar motion
• Proper motion
• Star catalog conversions
• Astrometric transformations
• Galactic Coordinates

Licensing

As of the February 2009 release, SOFA licensing changed to allow use for any purpose, provided certain requirements are met.^[1] Previously, commercial usage was specifically excluded and required written agreement of the SOFA board.^[2]

See also

• Naval Observatory Vector Astrometry Subroutines