Here is a list of all documented files with brief descriptions:

src
libnova
aberration.h
airmass.h
angular_separation.h
apparent_position.h
asteroid.h
comet.h
dynamical_time.h
earth.h
elliptic_motion.h
heliocentric_time.h
hyperbolic_motion.h
julian_day.h
jupiter.h
libnova.h
ln_types.h
lunar.h
mars.h
mercury.h
neptune.h
nutation.h
parabolic_motion.h
parallax.h
pluto.h
precession.h
proper_motion.h
refraction.h
rise_set.h
saturn.h
sidereal_time.h
solar.h
transform.h
uranus.h
utility.h
venus.h
vsop87.h