Investigation of the periodic systematic error in determining centers of star images in the CCD matrix of star sensor BOKZ-M60

We investigate the periodic systematic error found out in ground-based measurements of the star sensor BOKZ-M60. This error can be explained by periodic pixel structure of the sensor CCD matrix. Our conclusion is based on processing sufficiently long series of measurement data. The measurements were processed in a few stages. First, we approximate the motion of the star sky in the matrix plane using an appropriate mathematical model. Then we trace the motion of some individual stars relative to the model sky motion. Using spectral analysis, we found periodic components of their motion. The period of those components allow us to make the above conclusion.