VLA searches for formaldehyde and cyanoacetylene emission from comet P/Brorsen-Metcalf (1989o)

In Sep. 1989, Very Large Array (VLA) searches were conducted for both formaldehyde (H2CO) and cyanoacetylene (HC3N) emission from Comet P/Brorsen-Metcalf (1989o). In early July, this comet was outgassing strongly at a brighter than average preperihelion rate, and the hope was that it would continue to do so through perihelion. By observing the 1 sub 11 to 1 sub 10 transition of H2CO at 4,829.659 MHz (6 cm lambda) during the phase of maximum outgassing, it was expected that spectra would be collected with a high signal to noise ratio which would show the temporal behavior of formaldehyde relative to other molecules. During this same observation period, a search was also made for the J-1-0, F-2-1 rotational transition of cyanoacetylene at 9098.3321 MHz (3.3 cm lambda).