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).

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.

WWW: https://github.com/liberfa/erfa