SaVi is satellite visualization software that lets you create, run, examine, and modify satellite orbits in two and three dimensions. Simulations of Iridium, Globalstar, Galileo, GPS, and other satellite constellations are included. SaVi requires Tcl and Tk on a system with Unix libraries. SaVi works well with the 3D renderer Geomview. Geomview is optional, though recommended for its 3D rendering capabilities.
Xgravity is a program for the simulation of 3D gravitational motion of n-bodies. It reads a file with the current state of the bodies, and displays the motion. It features a nice isometric perspective, Red-Green stereographics, and a stereographic perspective which allows you to see the trace in "real" 3D. There is a GTK GUI interface in development, which gives you the ability to perform basic operations with the system, like modifing objects, rotating, eliminating drift, and launching a simulation.
COSMIX is a general purpose N body integrator. It allows simulation of the behavior of gravitational systems according to different physical theories. The current release is only a test release - it only supports the newtonian approximation. The project aims at tackling relativity in coming releases.
UFOClock draws an astronomical clock. From it you can read the time of day, phase of the lunar month, ratio of day to night, time until a solstice or equinox, and time until the end or beginning of twilight. The time of day depends on your location on the surface of the Earth, which you can enter on the command line or in a dotfile in your home directory. Location can be given as latitude/longitude or ZIP code. It is called UFO clock because it sort of looks like crop circles. It is based on Sundial by George Williams. It requires GLUT installed to run and the NOVAS library to build.
Remote Telescope System (RTS2) is an integrated system for remote observatory control. It is designed to keep an observatory running, protect it from elements, take images, ensure that pointing is good, react to TOOs, keep track of what was done, send you data, and help you to do science. It picks targets from a database table, stores image meta-data in a database, processes images, and stores WCS coordinates in the database. An abstract device layer enables control of all possible combinations of mounts, CCDs, photometers, and roof and cupola controllers.
INDI is an instrument-neutral distributed interface control protocol that aims to provide backend driver support and automation for a wide range of astronomical devices (telescopes, focusers, CCDs, etc.). Current supported devices include many telescopes, CCDs, filter wheels, focusers, and video cams. INDI is used in popular astronomy suites like Xephem, KStars, DCD, and Cartes Du Ciel.
CFITSIO is a library of C and Fortran subroutines for reading and writing data files in the FITS (Flexible Image Transport System) data format. It simplifies the task of writing software that deals with FITS files by providing an easy to use set of high-level routines that insulate the programmer from the internal complexities of the FITS file format.
TRIP is a general computer algebra system dedicated to celestial mechanics. It includes a numerical kernel and has interfaces to gnuplot and xmgrace. Computations can be performed with double, quadruple, or multi-precision. Users can dynamically load external libraries written in C, C++, or Fortran. Parallel computations on multivariate polynomials can be performed.