JCMT observations of the circumstellar envelope IRC+10216

The observations of the circumstellar envelope IRC+10216 with the James Clerk Maxwell Telescope (Hawaii) are presented. The radial CO distribution agrees in shape with the Kwan/Linke outflow model, but is lower in intensity by a factor of 0.54. The HCN intensity is nearly double that of CO, but drops off almost twice as rapidly with distance from the source centre. Single spectra at the source centre are also presented for the isotopes 13CO, H13CN, C34S and for the lower excitation 3-2 line of HCN and its isotope H13CN. The strength of the HCN lines suggests the dominance of radiative excitation and the existence of additional sources of carbon. The existing data on IRC+10216, is also lacking in reliability, particularly at higher frequencies. A more systematic program of high spatial resolution observations covering a range of excitation energies for several molecules and their isotopes is needed to provide an unambiguous basis for modeling