Knowledge Bank

New spectroscopic data were recorded for the two-top molecule methyl acetate with a chirped-pulse Fourier transform microwave spectrometer at room temperature and a jet cooled sub-millimeterwave spectrometer. More than 650 new lines with {\it J} up to 35 and {\it K} up to 15 were assigned. In total, approximately 1500 lines were fitted with 34 parameters using the program BELGI-C-2tops to a standard deviation close to the measurement error. More precise determinations of the top-top interaction and the {\it J}, {\it K} dependent parameters as well as the influence of the total rotation on the top-top interaction were carried out. The extension of the ground state spectrum of methyl acetate is a necessary step before searching for the first torsional excited transition in both torsional modes in the room temperature spectrum.