Proper Motion of the Large Magellanic Cloud Using QSO[CSC]s[/CSC] as an Inertial Reference System: The Q0459−6427 Field

Abstract

The proper motion of the Large Magellanic Cloud relative to one background quasi-stellar object is determined using 44 CCD frames obtained from 1989.0 to 2000.0 at the Cassegrain focus of the Cerro Tololo Inter-American Observatory 1.5 m telescope. This is the continuation of a previous study made for three other LMC "quasar fields" observed with the same telescope and equipment and processed in a similar way. The results obtained here are compared with those by other authors who used different approaches and reference systems for the proper-motion determinations and with those in the previous study. The results of our proper-motion determination are in agreement with those of the former studies, but they show discrepancies when compared with the results of the latter. The possible causes of this inconsistency are discussed. Also, from the newly determined proper motion, the LMC spatial velocity vector is calculated, which in turn is used to determine the lower limit of the mass of the Galaxy contained within 50 kpc from its center.