HCN, CO, CS, CN, and CO+ observations of comet Hyakutake (1996 B2)

In March and April 1996 we observed the comet Hyakutake (1996 B2) with the KOSMA 3-m telescope. We detected the J = 2−1 and 3−2 transitions of CO, and the J = 3−2 and 4−3 transitions of HCN on several days during this period. In addition we detected CS J = 7−6 on one occasion. We observed, but did not detect, several transitions of CN (N = 2−1 and N = 3−2), and CO+ N = 3−2. From our results we derive production rates of the different molecules or upper limits. The simultaneous observations of different transitions and different molecules allow a comparison of those rates and of the assumed excitation model. The HCN spectra show variability by about 50% on a time scale of hours.