This is the source code repository for ERFA (Essential Routines for Fundamental Astronomy). ERFA 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. Permission for this release has been obtained from the SOFA board, and is avilable in the LICENSE file included in this source distribution.

This version of ERFA (v0.0.1) is based on SOFA version "20120301_a", with the differences outlined below.

All references to "SOFA" in the source code have been changed to ERFA, and functions have the prefix era instead of iau.

To build and install a released version of ERFA in your OS's standard location, simply do:

./configure
make
make install

If you are using a developer version from github, you will need to first do ./bootstrap.sh before the above commands.

If you wish to build against the ERFA static library without installing, you will find it in $ERFAROOT/src/.libs/liberfa.a after running make.

Alternatively, if you wish to bundle the ERFA source code with a separate package, you can use the source_flattener.py script from the erfa-fetch repository to combine the ERFA source code into a single erfa.c source file, and an erfa.h include file. If possible, however, it is recommended that you provide an option to use a installed ERFA library, if it is present.