  Moving objects leave extended tracks in optical images acquired with a
telescope that is tracking stars or other targets. By searching images for
these tracks, one can obtain statistics on populations of space debris in Earth
orbit. The algorithm described here combines matched filtering with a Fourier
implementation of the discrete Radon transform and can detect long linear
tracks with high sensitivity and speed. Monte-Carlo simulations show that such
tracks, in a background of Poisson random noise, can be reliably detected even
if they are invisible to the eye. On a 2.2 GHz computer the algorithm can
process a 4096 x 4096-pixel image in less than a minute.
