Like many other late-type galaxies , the Milky Way contains a nuclear star cluster .
In this work we obtain the basic properties of its dominant old stellar population .
Firstly , we derive its structural properties by constructing a stellar surface density map of the central 1000 \arcsec using extinction corrected star counts from VISTA , WFC3/IR and VLT/NACO data .
We can describe the profile with a two-component models .
The inner , slightly flattened ( axis ratio of q = 0.80 \pm 0.04 ) component is the nuclear cluster , while the outer component corresponds to the stellar component of the circumnuclear zone .
We measure for the nuclear cluster a half-light radius of 178 \pm 51 \arcsec \approx 7 \pm 2 pc and a luminosity of M _ { \mathrm { Ks } } = -16.0 \pm 0.5 .
Secondly , we enlarge the field of view over which detailed dynamics are available from 1 pc to 4 pc .
We obtain more than 10000 individual proper motions from NACO data , and more than 2500 radial velocities from VLT/SINFONI data .
We determine the cluster mass by means of isotropic spherical Jeans modeling .
We fix the distance to the Galactic Center and the mass of the supermassive black hole .
We model the cluster either with a constant mass to light ratio or with a power law mass model with a slope parameter \delta _ { \mathrm { M } } .
For the latter we obtain \delta _ { \mathrm { M } } = 1.18 \pm 0.06 .
Assuming spherical symmetry , we get a nuclear cluster mass within 100 \arcsec of M _ { 100 \arcsec } = ( 6.09 \pm 0.53 | _ { \mathrm { fix } R _ { 0 } } \pm 0.97 | _ { R _ { 0 } } ) \times 10 ^ { 6 } M _ { \odot } for both modeling approaches .
A model which includes the observed flattening gives a 47 % larger mass , see Chatzopoulos et al .
2015 .
Our results slightly favor a core over a cusp in the mass profile .
By minimizing the number of unbound stars within 8 \arcsec in our sample we obtain a distance estimate of R _ { 0 } = 8.53 ^ { +0.21 } _ { -0.15 } kpc , where an a priori relation between R _ { 0 } and SMBH mass from stellar orbits is used .
Combining our mass and flux we obtain M / L = 0.51 \pm 0.12 M _ { \odot } / L _ { \odot, \mathrm { Ks } } .
This is roughly consistent with a Chabrier IMF .