VLA Searches for Formaldehyde and Cyanoacetylene Emission From Comet P/Brorsen-Metcalf (1989o)

In 1989 September we conducted VIA searches for both formaldehyde (H2CO) and cyanoacetylene (HC3N) emission from Comet P/Brorsen-Metcalf (19890). In early July, this comet was outgassing strongly at a brighter than average preperihelion rate, and our hope was that it would continue to do so through perihelion (1989 Sept. 11,9394). By observing the 111 - 110 transition of formaldehyde (H2CO) at 4,829.659 MHz (6 cm. λ) during the phase of maximum outgassing, we expected to collect spectra with a high signal-to-noise ratio which would show the temporal behavior of formaldehyde relative to other molecules. During this same observing period, we also searched for the J-1-0, F-2-1 rotational transition of cyanoacetylene at 9098.3321 MHz (3.3 cm. λ).