Essential Routines for Fundamental Astronomy
ERFA (Essential Routines for Fundamental Astronomy) is a C library containing key algorithms for astronomy, and is based on the SOFA library published by the International Astronomical Union (IAU), https://www.iausofa.org/ ERFA is intended to replicate the functionality of SOFA (aside from possible bugfixes in ERFA that have not yet been included in SOFA), but is licensed under a three-clause BSD license to enable its compatibility with a wide range of open source licenses. Permission for this release has been obtained from the SOFA board, and is available in the LICENSE file included in this source distribution.
Homepage: https://github.com/liberfa/erfa