Here are the classes, structs, unions and interfaces with brief descriptions:

Cnovas_cat_entry	Basic astrometric data for any sidereal object located outside the solar system
Cnovas_delaunay_args	Fundamental Delaunay arguments of the Sun and Moon, from Simon section 3.4(b.3)
Cnovas_frame	A set of parameters that uniquely define the place and time of observation
Cnovas_in_space	Data for an observer's location on Earth orbit
Cnovas_matrix	A 3x3 matrix for coordinate transformations
Cnovas_object	Celestial object of interest
Cnovas_observable	Spherical and spectral coordinate set
Cnovas_observer	Observer location
Cnovas_on_surface	Data for an observer's location on the surface of the Earth, and optional local weather data for refraction calculations only
Cnovas_orbital	Keplerian orbital elements for NOVAS_ORBITAL_OBJECT type
Cnovas_orbital_system	Specification of an orbital system, in which orbital elements are defined
Cnovas_planet_bundle	Position and velocity data for a set of major planets (which may include the Sun and the Moon also)
Cnovas_ra_of_cio	[deprecated]
Cnovas_sky_pos	Celestial object's place on the sky; contains the output from place()
Cnovas_timespec	A structure, which defines a precise instant of time that can be extpressed in any of the astronomical timescales
Cnovas_track	The spherical and spectral tracking position of a source, and its first and second time derivatives
Cnovas_transform	A transformation between two astronomical coordinate systems for the same observer location and time