Reinvestigation of the microwave and new high resolution far-infrared spectra of cis-methyl nitrite, CH3ONO: Rotational study of the two first torsional states

► The spectrum of methyl nitrite has been recorded in the MW and FIR region. ► Ground and first excited torsional state of cis-CH3ONO have been globally fitted. ► The global fit uses RAM Hamiltonian. ► Comparison between the constants obtained with two methods is described.