Here is a list of all files with brief descriptions:

[detail level 123]

include
novas-calceph.h	SuperNOVAS functions interfacing with the CALCEPH C library
novas-cspice.h	SuperNOVAS functions interfacing with the NAIF CSPICE Toolkit
novas.h	SuperNOVAS types, definitions, and function prototypes
src
c99
calendar.c	Various functions to convert between calendar dates and Julian days
cio.c	Functions to calculate or access the Celestial Intermediate Origin (CIO) location
earth.c	Various functions relating to Earth position and rotation
ephemeris.c	Functions that allow to define or access Solar-system ephemeris data
equator.c	Various functions for calculating the equator and equinox of date, and related quatities
frames.c	High-level and efficient astrometric calculations using observing frames
grav.c	Various functions to deal with gravitational effects of the major Solar-system bodies on the astrometry
itrf.c	Transformations of station coordinates, velocities, and Earth orinetation parameters (EOP) between various ITRF realizations, and conversion between Cartesian (x, y, z) and geodetic (longitude, latitude, altitude) coordinates w.r.t
moon.c
naif.c	Solar system ID mappings between NOVAS and NASA's Navigation and Ancillary Information Facility (NAIF), which is used by the JPL ephemeris systems
nutation.c	SuperNOVAS implementations for the IAU2000 nutation series calculations, with varying trade-offs between computational cost and precision
observer.c	This module provides a set of functions that define an astronomical observer location, or ones that relate to observer location
orbital.c	Function relating to the use of Keplerian orbital elements
parse.c	Various functions to parse string specifications of angles, time, dates, and coordinate epochs
place.c	Various convenience variants of the NOVAS C place() function
planets.c	Calculate approximate positions and velocities for the major planets, Sun, Earth-Moon Barycenter (EMB), and the Solar-system Barycenter (SSB), mainly by using Keplerian orbital elements
refract.c	A collection of refraction models and utilities to use with novas_app_to_hor() or novas_hor_to_app()
solsys-calceph.c	Solar-system ephemeris lookup via the CALCEPH C library
solsys-cspice.c	Solar-system ephemeris lookup via the NAIF CSPICE library
solsys-ephem.c	Major planet ephemeris lookup via the function, which was configured by set_ephem_provider()
solsys3.c	Planet calculator functions for the Earth and Sun only, with an orbital model fitted to the DE405 ephemerides by JPL
spectral.c	Various spectral / velocity related functions
system.c	Various transformations between different coordinate systems used in astronomy, such as equatorial, ecliptic, Galactic, or local horizontal coordinate systems
target.c	This module contains functions that define an observing target, or which are target related
timescale.c	Functions to define and use different astronomical timescales and to convert among them
transform.c	Various functions to transform rectangular equatorial vectors (positions or velocities) between different equatorial coordinate systems
util.c	Various commonly used routines used throughout the SuperNOVAS library