We describe an observing campaign using the Very Long Baseline Array ( VLBA ) to monitor the time-evolution of the v = 1 ,J = 1 - 0 SiO maser emission towards the Mira variable TX Cam .
The data reported here cover the period 1997 May 24 to 1999 February 19 , during which the SiO maser emission was imaged at approximately bi-weekly intervals .
The result is an animated movie at an angular resolution of \sim 500 \mu as , over a full pulsation period , of the gas motions in the near circumstellar environment of this star , as traced by the SiO maser emission .
This paper serves to release the movie and is the first in a series concerning the scientific results from this observing campaign .
In this paper , we discuss the global proper motion of the SiO maser emission as a function of pulsation phase .
We measure a dominant expansion mode between optical phases \phi \sim 0.7 - 1.5 
confirming ballistic deceleration , and compare this to predictions from existing pulsation models for late-type , evolved stars .
Local infall and outflow motions are superimposed on the dominant expansion mode , and non-radial local gas motions are also evident for individual SiO maser components .
The overall morphology and evolution of the SiO emission deviates significantly from spherical symmetry , with important implications for models of pulsation kinematics in the near-circumstellar environments of Mira variables .