Overview of the proper motion measurements for the two datasets from ACS F850LP and WFC3-IR F098M. Left panel: proper motions of stars as measured using ACS F850LP astrometry. The background image is from 2003 and is oriented at a position angle of 87.6 deg. Proper motions are available only for stars that overlap between the 2003 and 2004 pointings. The five candidate companion sources (black circles) and center of expansion (red dot) are labeled. Right panel: proper motions of stars as measured using WFC3-IR F098M astrometry from 2010 to 2011. The background image is from 2010 and is oriented at a position angle of −23.3 deg. The five candidate companion sources (black circles) and center of expansion (red dot) are labeled.