The ESO-VLT MIKiS survey reloaded: velocity dispersion profile and
  rotation curve of NGC 1904
  We present an investigation of the internal kinematic properties of M79 (NGC
1904). Our study is based on radial velocity measurements obtained from the
ESO-VLT Multi-Instrument Kinematic Survey (MIKiS) of Galactic globular clusters
for more than 1700 individual stars distributed between $\sim
0.3^{\prime\prime}$ and $770^{\prime\prime}$ ($\sim14$ three-dimensional
half-mass radii), from the center. Our analysis reveals the presence of ordered
line-of-sight rotation with a rotation axis almost aligned along the East-West
direction and a velocity peak of $1.5$ km s$^{-1}$ at $\sim 70^{\prime\prime}$
from the rotation axis. The velocity dispersion profile is well described by
the same King model that best fits the projected density distribution, with a
constant central plateau at $\sigma_0\sim 6$ km s$^{-1}$. To investigate the
cluster rotation in the plane of the sky, we have analyzed the proper motions
provided by the Gaia EDR3, finding a signature of rotation with a maximum
amplitude of $\sim 2.0$ km s$^{-1}$ at $\sim 80^{\prime\prime}$ from the
cluster center. Analyzing the three-dimensional velocity distribution, for a
sub-sample of 130 stars, we confirm the presence of systemic rotation and find
a rotation axis inclination angle of $37${\deg} with respect to the
line-of-sight. As a final result, the comparison of the observed rotation
curves with the results of a representative N-body simulation of a rotating
star cluster shows that the present-day kinematic properties of NGC 1904 are
consistent with those of a dynamically old system that has lost a significant
fraction of its initial angular momentum.
