Accuracy estimation of determining attitude of coordinate systems of BOKZ astromeasuring devices

Astromeasuring devices (star sensors) of BOKZ family allow to find parameters, which define the attitude of their own coordinate systems with respect to the Geocentric Equatorial Inertial System, by observing regions the star sky. The last system is realized by star coordinates related to the epoch J2000 in the on board catalogue. Accuracy of definition of attitude parameters is influenced by a great number of factors; therefore an estimation of the contribution of each of them in the total error is not always possible. On that reason, we analyze fluctuations of rather long series of definitions of attitude parameters received by BOKZ devices in ground-based tests and in the conditions of a real space flight. On the basis of processing of this data the mathematical model of an error of measurements of devices of family BOKZ is offered.