About us

SOFA operates under the auspices of the International Astronomical Union (IAU) to provide algorithms and software for use in astronomical computing. The initiative is managed by an international panel, the SOFA Board, appointed through IAU Division A. The Board obtains the latest IAU-approved models and theories from the fundamental-astronomy community, implements them as computer code and checks them for accuracy. SOFA works closely with all the Commissions of the Division and with the International Earth Rotation and Reference Systems Service (IERS).

The SOFA Collection consists of two libraries of routines, one coded in Fortran 77 the other in ANSI C. There is a suite of vector/matrix routines and various utilities that underpin the astronomy algorithms, which include routines for the following:

  • Astrometry

  • Calendars

  • Time Scales

  • Ecliptic Coordinates

  • Earth Rotation and Sidereal Time

  • Ephemerides (medium precision)

  • Fundamental Arguments

  • Galactic Coordinates

  • Geocentric/Geodetic Transformations

  • Precession, Nutation and Polar Motion

  • Star Catalog Conversion

The link for the current Fortran 77 and ANSI C software gives information on how to obtain it and instructions on its use. Also provided are two validation programs — one for each language. Guides with examples for many of the SOFA routines can be found in the various Cookbooks.

Access to the archive of all previous releases may be obtained from SOFA's software archive. A selection of reports and papers from the IAU SOFA initiative is also available.

IAU Standards of Fundamental Astronomy Board

Acknowledgements

The SOFA Board gratefully acknowledges the support it receives from the institutions and funding bodies of its members. The Board also acknowledges the provision of this web site by HM Nautical Almanac Office (HMNAO), part of the UK Hydrographic Office.

Current members

  • John Bangert — United States Naval Observatory (retired)

  • Steven Bell — His Majesty's Nautical Almanac Office (Webmaster)

  • Maria Davis — United States Naval Observatory (IERS)

  • Mickaël Gastineau — Paris Observatory, IMCCE

  • Catherine Hohenkerk — His Majesty's Nautical Almanac Office (former Chair, retired)

  • Li Jinling — Shanghai Astronomical Observatory

  • Zinovy Malkin — Pulkovo Observatory, St Petersburg

  • Wendy Puatua — United States Naval Observatory

  • Scott Ransom — National Radio Astronomy Observatory

  • Nick Stamatakos — United States Naval Observatory

  • Patrick Wallace — RAL Space (retired)

  • Toni Wilmot — His Majesty's Nautical Almanac Office (Chair)

    The email address for the SOFA Board Chair is toni.wilmot@ukho.gov.uk.

Past members

  • Wim Brouw — University of Groningen

  • Mark Calabretta — Australia Telescope National Facility

  • Nicole Capitaine — Paris Observatory

  • William Folkner — Jet Propulsion Laboratory

  • Anne-Marie Gontier — Paris Observatory

  • George Hobbs — Australia Telescope National Facility

  • George Kaplan — United States Naval Observatory

  • Brian Luzum — United States Naval Observatory

  • Dennis McCarthy — United States Naval Observatory

  • Skip Newhall — Jet Propulsion Laboratory

  • Jeffrey Percival — University of Wisconsin

  • Jin Wen-Jing— Shanghai Astronomical Observatory