MARVEL Analysis of the Measured High-resolution Spectra of CO Isotopologues

Abstract: Carbon monoxide is thought to be the second most abundant molecule in the Universe. This makes observation of both its parent isotopologue ($^{12}$C$^{16}$O) and its stable isotopologues, $^{13}$C$^{16}$O, $^{12}$C$^{18}$O, $^{12}$C$^{17}$O, $^{13}$C$^{18}$O and $^{13}$C$^{17}$O, important in variety of objects. Here the MARVEL (Measured Active Rotational-Vibrational Energy Levels) algorithm is used to determine precise rotational vibrational energy levels for the five minor isotopologues of carbon monoxide in their electronic ground state. A review of 27 literature sources yields 3716, 1454, 89, 728 and 57 validated transitions for $^{13}$C$^{16}$O, $^{12}$C$^{18}$O, $^{12}$C$^{17}$O, $^{13}$C$^{18}$O and $^{13}$C$^{17}$O, respectively, giving 863, 499, 33, 345 and 45 empirically determined, rotation vibration energy levels, respectively.