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We report the first determination of the distance to the Galactic centrebased on the kinematics of halo objects. We apply the statistical-parallaxtechnique to the sample of ~2500 Blue Horizontal Branch (BHB) stars compiled byXue et al. (2011) to simultaneously constrain the correction factor to thephotometric distances of BHB stars as reported by those authors and thedistance to the Galactic centre to find R0=8.2+/-0.6 kpc. We also find that theaverage velocity of our BHB star sample in the direction of Galactic rotation,V0=-240+/-4 km/s, is greater by about 20 km/s in absolute value than thecorresponding velocity for halo RR Lyrae type stars (V0=-222+/-4 km/s) in theGalactocentric distance interval from 6 to 18 kpc, whereas the total (sigma V)and radial (sigma r) velocity dispersion of the of the BHB sample are smallerby about 40-45 km/s than the corresponding parameters of the velocitydispersion ellipsoid of halo RR Lyrae type variables. The velocity dispersiontensor of halo BHB stars proved to be markedly less anisotropic than thecorresponding tensor for RR Lyrae type variables: the corresponding anisotropyparameter values are equal to beta(BHB)=0.51+/-0.02 and beta(RR)=0.71+/-0.03,respectively.

Calibrating the BHB Star Distance Scale and the Halo Kinematic Distance to the Galactic Centre