Provides basic functionalities to calculate the position of
satellites given a known state vector. The package includes implementations
of the SGP4 and SDP4 simplified perturbation models to propagate orbital
state vectors, as well as utilities to read TLE files and convert coordinates
between different frames of reference.
Felix R. Hoots, Ronald L. Roehrich and T.S. Kelso (1988) < https://celestrak.com/NORAD/documentation/spacetrk.pdf>.
David Vallado, Paul Crawford, Richard Hujsak and T.S. Kelso (2012)