An Analysis of HCN Observations of The Galactic Centre's Circumnuclear
  Disk
  The Circumnuclear Disk (CND) is a torus of dust and moleular gas rotating
about the galactic centre and extends from 1.6 to 7pc from the central massive
black hole SgrA*. Large Velocity Gradient modelling of selected transitions of
HCN rotational collisions with molecular hydrogen is used to infer Hydrogen
density and HCN opacities. The analysis concludes that the predicted hydrogen
number density of CND clumps is about 10^6 which is insufficiently dense to
withstand the tidal shear forces generated by SgrA* and the stellar group in
the cavity between the galactic centre and the CND.
