Abstract: A star sensor which includes a charge-coupled device (CCD) for detecting light rays of a star and for producing an output representative of the distribution of the light rays of the star over the CCD. The CCD output is filtered and a detecting circuit is used for finding the points where the output signal voltage of the filter equals a predetermined level. A computing circuit compares the output of the detecting circuit to a reference voltage to locate peak values of the CCD signal. A data processor uses the generated outputs which correspond to the peak values to calculate the brightness and position of the star.