Abstract: To satisfy the need of outfield tests of star sensors, a method is put forward to construct the reference attitude benchmark. Firstly, its basic principle is introduced. Then, all the separate conversion matrixes are deduced, which include the conversion matrix Cwi responsible for the transformation from the earth centered inertial frame i to the earth-centered earth-fixed frame w according to the time of an atomic clock, the conversion matrix Ctwfrom frame w to the geographic frame t, the conversion matrix Cpt from frame t to the platform frame p, and the matrix Csp from frame p to the star sensors frame s. As a result, the attitude matrix Csi of the star sensor relative to the frame i can be obtained using all the three matrixes as the multiplicative factors. Next, the reference attitude angles for star sensor outfield tests can be calculated from the transformation matrix Csi from frame i to s. Finally, the computer program is given to solve the reference attitudes, and the error curves are drawn about the three axis attitude angles, whose absolute maximum error is less than 0.25″. The simulating results manifest that the method by precise timing to acquire the absolute reference attitude benchmark is feasible for star sensor outfield tests.

Key words: star sensor, attitude benchmark, atomic clock, absolute attitude, coordinate transformation；inertial frame