VVVX-Gaia Discovery of a Low Luminosity Globular Cluster in the Milky
  Way Disk
  Milky Way globular clusters (MW GCs) are difficult to identify at low
Galactic latitudes because of high differential extinction and heavy star
crowding. The new deep near-IR images and photometry from the VISTA Variables
in the Via L\'actea Extended Survey (VVVX) allow us to chart previously
unexplored regions. Our long term aim is to complete the census of MW GCs. The
immediate goals are to estimate the astrophysical parameters, measuring their
reddenings, extinctions, distances, total luminosities, proper motions, sizes,
metallicities and ages. We use the near-IR VVVX survey database, in combination
with Gaia DR2 optical photometry, and with the Two Micron All Sky Survey
(2MASS) photometry. We report the detection of a heretofore unknown Galactic
Globular Cluster at $RA =$ 14:09:00.0; $DEC=-$65:37:12 (J2000). We calculate a
reddening of $E(J-K_s)=(0.3\pm 0.03)$ mag and an extinction of
$A_{K_s}=(0.15\pm 0.01)$ mag for this new GC. Its distance modulus and
corresponding distance were measured as $(m-M)=(15.93\pm0.03)$ mag and
$D=(15.5\pm1.0)$ kpc, respectively. We estimate the metallicity and age by
comparison with known GCs and by fitting PARSEC and Dartmouth isochrones,
finding $[Fe/H]=(-0.70\pm0.2)$ dex and $t=(11.0\pm1.0)$ Gyr. The mean GC PMs
from Gaia are $\mu_{\alpha^\ast}=(-4.68 \pm 0.47 )$ mas $yr^{-1}$ and
$\mu_{\delta}=(-1.34 \pm 0.45)$ mas $yr^{-1}$. The total luminosity of our
cluster is estimated to be $M_{Ks}=(-7.76\pm 0.5)$ mag. We have found a new
low-luminosity, old and metal-rich globular cluster, situated in the far side
of the Galactic disk, at $R_{G}=11.2$ kpc from the Galactic centre, and at
$z=1.0$ kpc below the plane. Interestingly, the location, metallicity and age
of this globular cluster are coincident with the Monoceros Ring (MRi)
structure.
