WCSLIB is a C library, supplied with a full set of Fortran wrappers, which implements the "World Coordinate System" (WCS) standard in FITS (Flexible Image Transport System). It also includes a PGPLOT-based routine, PGSBOX, for drawing general curvilinear coordinate graticules, and a number of utility programs. The FITS "World Coordinate System" (WCS) convention defines keywords and usage which provide descriptions of astronomical coordinate systems in a FITS image header.
I is a programming language that was designed to be efficient to write and run. The system incorporates many major libraries, allowing the creation of major projects such as Aciqra. It is an interpreted language and supports CGI scripting through the use of the CGI for Aciv/I extension.
SAOTrace is a suite of software designed to simulate the as-built performance of grazing-angle X-ray optics using the ray-tracing approach. It is derived from portions of the NASA OSAC (Optical Surface Analysis Code) software suite. It can model nested conical as well as flat optical designs, and includes the ability to model arbitrary support structures and baffles. It can model non-ideal multi-layer reflective coatings as well as scattering from the optical surfaces.
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.