The Naval Observatory Vector Astrometry Software (NOVAS) is a software library for astrometry

Astrometry

Astrometry is the branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. The information obtained by astrometric measurements provides information on the kinematics and physical origin of our Solar System and our Galaxy, the Milky...

-related numerical

Numerical analysis

Numerical analysis is the study of algorithms that use numerical approximation for the problems of mathematical analysis ....

 computations. It is developed by the Astronomical Applications Department, United States Naval Observatory

United States Naval Observatory

The United States Naval Observatory is one of the oldest scientific agencies in the United States, with a primary mission to produce Positioning, Navigation, and Timing for the U.S. Navy and the U.S. Department of Defense...

. Currently, NOVAS has two different editions for C and Fortran

Fortran

Fortran is a general-purpose, procedural, imperative programming language that is especially suited to numeric computation and scientific computing...

 respectively.
The algorithms used by NOVAS are based on vector astrometry theories and the IAU

IAU

IAU may refer to:*International Astronomical Union*International American University*International American University College of Medicine*International Association of Universities*International Association of Ultrarunners...

 resolutions. Instead of using trigonometric formulae from spherical astrometry, NOVAS uses the matrix

Matrix (mathematics)

In mathematics, a matrix is a rectangular array of numbers, symbols, or expressions. The individual items in a matrix are called its elements or entries. An example of a matrix with six elements isMatrices of the same size can be added or subtracted element by element...

 and vector formulation which is more rigorous.