Proper motions for HST observations in three off-axis bulge fields
  Aims. This is the second in a series of papers that attempt to unveil the
kinematic structure of the Galactic bulge through studying radial velocities
and proper motions. We report here ~15000 new proper motions for three low
foreground-extinction off-axis fields of the Galactic bulge. Methods. Proper
motions were derived from a combination of Hubble Space Telescope Wide Field
Planetary Camera 2 (WFPC2) and Advanced Camera for Surveys (ACS) images taken 8
and 9 years apart, and ACS observations taken 9 and 10 years apart, and they
reach accuracies better than 0.9 mas/yr for more than ~10000 objects with
magnitudes F814W < 24. Results. The proper motion distributions in these fields
are similar to those of Galactic minor axis bulge fields. We observe the
rotation of main sequence stars below the turn-off within the Galactic bulge,
as in the minor axis fields. Conclusions. Our stellar proper motions
measurements show a significant bulge rotation for fields as far from the
galactic plane as b=-8.
