title: Rectangular Coordinates for Earth Satellites in PyEphem
body: <p>I have searched through a large number of PyEphem webpages, downloaded code, and investigated objects, but I have not found a way to get the earth-centered rectangular coordinates of an earth satellite in some nominally inertial coordinate system. Have I missed something obvious? I am looking for the 'traditional' x, y, z and x-dot, y-dot, z-dot. Many Thanks for any suggestions.</p>