The Standards of Fundamental Astronomy (SOFA)
software libraries
In computer science, a library is a collection of non-volatile resources used by computer programs, often for software development. These may include configuration data, documentation, help data, message templates, pre-written code and subro ...
are a collection of
subroutines
In computer programming, a function or subroutine is a sequence of program instructions that performs a specific task, packaged as a unit. This unit can then be used in programs wherever that particular task should be performed.
Functions may ...
that implement official
International Astronomical Union
The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...
(IAU)
algorithms
In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...
for
astronomical
Astronomy () is a natural science that studies celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and evolution. Objects of interest include planets, moons, stars, nebulae, galaxi ...
computations.
As of February 2009 they are available in both
Fortran and
C source code
In computing, source code, or simply code, is any collection of code, with or without comments, written using a human-readable programming language, usually as plain text. The source code of a program is specially designed to facilitate the w ...
format.
Capabilities
The subroutines in the libraries cover the following areas:
*
Calendars
A calendar is a system of organizing days. This is done by giving names to periods of time, typically days, weeks, months and years. A date is the designation of a single and specific day within such a system. A calendar is also a ph ...
*
Time scales
Time scale may refer to:
*Time standard, a specification of either the rate at which time passes, points in time, or both
*A duration or quantity of time:
**Orders of magnitude (time) as a power of 10 in seconds;
**A specific unit of time
* Geolog ...
*
Earth's rotation and
sidereal time
*
Ephemerides
In astronomy and celestial navigation, an ephemeris (pl. ephemerides; ) is a book with tables that gives the trajectory of naturally occurring astronomical objects as well as artificial satellites in the sky, i.e., the position (and possibly ...
(limited precision)
*
Precession
Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In oth ...
,
nutation
Nutation () is a rocking, swaying, or nodding motion in the axis of rotation of a largely axially symmetric object, such as a gyroscope, planet, or bullet in flight, or as an intended behaviour of a mechanism. In an appropriate reference frame ...
,
polar motion
Polar motion of the Earth is the motion of the Earth's rotational axis relative to its crust. This is measured with respect to a reference frame in which the solid Earth is fixed (a so-called ''Earth-centered, Earth-fixed'' or ECEF reference ...
*
Proper motion
*
Star catalog
A star catalogue is an astronomical catalogue that lists stars. In astronomy, many stars are referred to simply by catalogue numbers. There are a great many different star catalogues which have been produced for different purposes over the years, ...
conversions
*
Astrometric
Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, the Milky Way.
His ...
transformations
*
Galactic Coordinates
The galactic coordinate system is a celestial coordinate system in spherical coordinates, with the Sun as its center, the primary direction aligned with the approximate center of the Milky Way Galaxy, and the fundamental plane parallel to an a ...
Licensing
As of the February 2009 release, SOFA
licensing
A license (or licence) is an official permission or permit to do, use, or own something (as well as the document of that permission or permit).
A license is granted by a party (licensor) to another party (licensee) as an element of an agreeme ...
changed to allow use for any purpose, provided certain requirements are met. Previously, commercial usage was specifically excluded and required written agreement of the SOFA board.
[.]
See also
*
Naval Observatory Vector Astrometry Subroutines
The Naval Observatory Vector Astrometry Software (NOVAS) is a software library for astrometry-related numerical computations. It is developed by the Astronomical Applications Department, United States Naval Observatory. Currently, NOVAS has thre ...
References
External links
SOFA Home PageScholarpedia overview of SOFAInternational Astronomical Union
an
Working group "Standards of Fundamental Astronomy
Celestial mechanics
Astronomical coordinate systems
Numerical software
Astronomy software
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