Molecule searches in Comet Kohoutek /1973f/ at microwave frequencies

Abstract Nine transitions of the possible parent molecules H 2 O, NH 3 , CH 3 OH and N 2 O as well as the OH radical were searched for in Comet Kohoutek (1973f) in the frequency range 22.2–25.2 GHz. These molecules were not detected, but the upper limits for the optical depth, mean column density and the production rate are derived for each of the molecules. These results are discussed and compared with the reported detections of HCN and CH 3 CN emission and OH absorption.