An axisymmetric kinematic model of the velocity field of H I gas in the Galactic Centre

21-cm observations have been used to provide limits on possible rotation and expansion velocity fields of the gas in the inner regions (R < 5 kpc) of the Galaxy. A least-squares fit to the observed extreme radial velocities gives rotation and expansion velocity curves which are compared with previous estimates of the velocity field. A polynomial approximation to the best-fitting model has been used to locate 21-cm emission features in space, as well as to estimate the H I density distribution as a function of distance to the Galactic Centre. (author)