Precession und Galactic Rotation Derived from McCormick and Cape Proper Motions in the Systems of FK3, N30, and FK4

Abstract

view Abstract Citations (40) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Precession und Galactic Rotation Derived from McCormick and Cape Proper Motions in the Systems of FK3, N30, and FK4 Fricke, Walter Abstract The proper motions of faint stars provide a suitable basis for the determination of precession and galactic rotation, if the motions are known with respect to a fundamental system. For the purpose of this investiga- tion the McCormick and Cape proper motions of stars of average photovisual magnitude 11.1, presented by Williams and Vyssotsky in the FK3 system, were reduced to the systems of N30 and FK4. In this paper it is shown that the correction APi to Newcomb's lunisolar precession has the same value in the systems FK3, N30, and FK4, provided that the determinations are based on identical parts of the sky and that equal systems of weights are applied. Since it is not possible to exclude systematic errors from the McCormick and Cape material satisfactorily, there remains the interval +1'.'08+0'.'12<APi< +1'.'38+0'.'08 for the centennial value of the correction. A]l three systems give the same value Q -0'.' 16+0'.'03 of Oort's constant corresponding to B = -7.6+1.4 km kpc-1. Oort's constant P differs slightly in the three systems and depends on the weight of the proper motions in different parts of the sky. The average value of P obtained from the three systems is P = +0'.'33+0'.'04 corresponding to A = + 15.5+1.9 km . With equal weight for McCormick and Cape motions, the value in the FK4 system is A =12 km . It is shown that some previous differential solutions of the problem have led to erroneous results because important characteristics of the primary solutions were disregarded. Publication: The Astronomical Journal Pub Date: June 1967 DOI: 10.1086/110287 Bibcode: 1967AJ.....72..642F full text sources ADS |