2025ApJ...986..136M

New measurements of nitrosomethane (CH₃NO), a formamide isomer, were done up to 660 GHz. The molecule exhibits internal rotation motion from the CH₃ group, and therefore the analysis with a dedicated rho-axis method code, RAM36, was used. A total of 2035 lines for v_t = 0 and 1 states of A and E symmetries were fitted with an rms deviation of 41.1 kHz, with the maximum quantum numbers values J = 30 and K_a = 15. Using these new data, CH₃NO was searched in the cold dark cloud Taurus Molecular Cloud 1 as well as the high mass star-forming regions Sgr B2(N) and NGC 6334I. CH₃NO was not observed in any of the sources, 3σ column density upper limits were determined, and we discuss the implications for the chemistry of CH₃NO in the interstellar medium. The accurate spectroscopic prediction of its spectra provided in this work will allow astronomers to continue the search of CH₃NO in other interstellar sources.