Plot Digitizer is a Java program used to digitize scanned plots of functional data. Written in Java. autotracing is supported on Mac OSX, Windows and Linux. From MP.
Periodic table of elements, as large PNG image. There is copyright on the design, although I cannot see what is so special about it. Let's be thankful that Mendeleev was more generous.
This chronology covers period starting from Perrin and Roentgen discoveries in 1895 up to the 1995 evidence of the top quark from FNAL, and is continuously maintained up to date. Has links to many historic papers.
The GPS precise orbits are derived using 24 hour data segments from the global GPS network coordinated by the International GPS Service (IGS). Provides links to coordinate transformation (geoid) computations and to the continuously operating [GPS] reference stations.
C/C++ version of the orbit models used with TLE data.
Source code for astronomical calculations, including satellite orbits.
See also https://github.com/Bill-Gray/sat_code/ which is licensed under the GPL V2.