Proper motion of the Large Magellanic Cloud using QSOs as an inertial reference system

The proper motion of the Large Magellanic Cloud (LMC) relative to three background quasi-stellar objects has been determined using 125 CCD frames taken from 1989.0 to 1997.2 at the Cassegrain focus of the CTIO 1.5 m telescope. The observation and reduction methods are fully described. The results are compared with those obtained by other authors who use different methods and reference systems for the proper motions. This comparison results in a good agreement for mu(alpha) cos delta and a rather large discrepancy for mu(delta). Our LMC proper motion seems to indicate that the LMC is not leading the Magellanic Stream. Finally, 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. The possible consequences of our results on the dynamical status of the LMC are discussed.