HCO(+), H(C-13)N, and H(C-12)N aperture synthesis observations of the circumnuclear ring in the Galactic center

The present 1988 and 1990 observations of the Sgr A West J = 1-0 transition lines of H(C-13)N and HCO(+), as well as a remapping of H(C-12)N J = 1-0 spectral line data, show that the clumps in the Galactic center's ring have an HCO(+)/HCN abundance that is 5-15 times lower than that which is measured in interstellar, quiescent molecular clouds. The HCN/H2 abundance ratio is also unusually large.