Conclusions on Galactic Kinematics from Proper Motions with Respect to Galaxies

Abstract

A comparison has been made between the results for precessional corrections and parameters of galactic rotation derived from fundamental proper motions and those measured with respect to galaxies at Lick and at Pulkovo. It is found that the results derived from the proper motions in declination are in fair agreement with each other. Since lunisolar precession and Oort’s constant B follow mainly from µ _δ , it can be concluded that the fundamental system and the reference system of galaxies are identical within the range of errors of measurement. No hitherto undetected systematic motion of stars can be reliably deduced. The proper motions in right ascension measured at Lick and at Pulkovo differ from each other by more than one second of arc per century, and the fundamental µ _α lie very near to the mean of both. Although the total discrepancy cannot be explained at present, part of it appears to be due to systematic errors depending on the magnitude.