This web site contains Fortran 77 and Fortran 90 subroutines and functions that can be used to solve a variety of practical problems in orbital mechanics, including: Convert a calendar date to a Julian date, Convert a Julian date to a calendar date, Convert an ECI state vector to classical orbital elements Convert classical orbital elements to an ECI state vector, Convert geocentric coordinates to geodetic coordinates, Danby's solution of Kepler's equation, Kozai orbit propagation  ECI version, Kozai orbit propagation  ECF version, Twobody orbital motion  Shepperd's method, Twobody orbital motion  Danby/Stumpff method, Firstorder equations of orbital motion (J2 gravity), Ephemeris of the planets  Meeus algorithm, Ephemeris of the Sun  LPPF algorithm, Ephemeris of the Moon  LPPF algorithm, Greenwich apparent sidereal time, Trig, vector and numerical analysis utility routines. Submitted: Feb 29, 2000
