Discovery of VVV CL001. A Low-Mass Globular Cluster Next to UKS~1 in the
  Direction of the Galactic Bulge
  Context: It is not known how many globular clusters may have been left
undetected towards the Galactic bulge. Aims: One of the aims of the VISTA
Variables in the Via Lactea (VVV) Survey is to accurately measure the physical
parameters of the known globular clusters in the inner regions of the Milky Way
and to search for new ones, hidden in regions of large extinction. Methods:
Deep near infrared images give deep JHKs-band photometry of a region
surrounding the known globular cluster UKS 1 and reveal a new low-mass globular
cluster candidate that we name VVV CL001. Results: We use the horizontal branch
red clump in order to measure E(B-V)~2.2 mag, $(m-M)_0$=16.01 mag, and D=15.9
kpc for the globular cluster UKS 1. Based on the near-infrared colour magnitude
diagrams, we also measure that VVV CL001 has E(B-V)~2.0, and that it is at
least as metal-poor as UKS 1, however, its distance remains uncertain.
Conclusions: Our finding confirms the previous projection that the central
region of the Milky Way harbors more globular clusters. VVV CL001 and UKS 1 are
good candidates for a physical cluster binary, but follow-up observations are
needed to decide if they are located at the same distance and have similar
radial velocities.
