  We use deep multi-epoch near-IR images of the VISTA Variables in the Via
Lactea (VVV) Survey to measure proper motions (PMs) of stars in the Milky Way
globular cluster FSR1716 = VVV-GC05. The color-magnitude diagram of this
object, made using PM selected members, shows an extended horizontal branch,
nine confirmed RR Lyrae members in the instability strip, and possibly several
hotter stars extending to the blue. Based on the fundamental-mode (ab-type) RR
Lyrae stars that move coherently with the cluster, we confirmed that FSR1716 is
an Oosterhoff I globular cluster with a mean period Pab = 0.574 days.
Intriguingly, we detect tidal extensions to both sides of this cluster in the
spatial distribution of PM selected member stars. Also, one of the confirmed
RRabs is located 11 arcmin in projection from the cluster center, suggesting
that FSR1716 may be losing stars due to the gravitational interaction with the
Galaxy. We also measure radial velocities (RVs) for five cluster red giants
selected using the PMs. The combination of RVs and PMs allow us to compute for
the first time the orbit of this globular cluster, using an updated Galactic
potential. The orbit results to be confined within |Zmax | < 2.0 kpc, and has
eccentricity 0.4 < e < 0.6, with perigalactic distance 1.5 < Rperi (kpc) < 2.3,
and apogalactic distance 5.3 < Rapo (kpc) < 6.4. We conclude that, in agreement
with its relatively low metallicity ([Fe/H]= -1.4 dex), this is an inner halo
globular cluster plunging into the disk of the Galaxy. As such, this is a
unique object to test the dynamical processes that contribute to the disruption
of Galactic globular clusters.
