Most satellite tracking programs calculate the nominal trajectory of the satellite based on the orbital elements and then allow the user to correct it due to inaccuracies in the telescope, the clock and the elements themselves. This correction is often done with the computer mouse. 

During Summer 2002 I worked on a program which reads the camera during the pass and corrects the telescope automatically. Here is a schematic of how it works:

These graphs show the first successful results for the ISS. 

	Top Left. The nominal trajectory. RA is in red and declination in blue.
	Bottom left. The corrections made to the trajectory by the automatic controller. Again RA is in red and declination in blue.
	Right. The position of the satellite in the frame. Due to the orientation of the camera RA is the column and declination the row. The dimension of the frame is about 4.4x3.3arcmin or around 0.04degs. As can be seen the satellite is constrained to within about 0.01degs.

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