Global Multi-isotopologue fit of measured rotation and vibration-rotation line positions of CO in X 1σ + state and new set of mass-independent Dunham coefficients

A set of mass-independent U _mj and Δ _mj parameters globally describing vibration-rotation energy levels of the CO molecule in the X ¹σ ⁺ ground electronic state was fitted to more than 19,000 transitions of ¹²C ¹⁶O, ¹³C ¹⁶O, ¹⁴C ¹⁶O, ¹²C ¹⁷O, ¹³C ¹⁷O, ¹²C ¹⁸O, and ¹³C ¹⁸O isotopologues collected from the literature. The maximal values of the vibrational V and the rotational J quantum numbers included in the fit was 41 and 128, respectively. The weighted standard deviation of the fit is 66. Fitted parameters were used for calculation of Dunham coefficients Y _mj for nine isotopologues ¹²C ¹⁶O, ¹³C ¹⁶O, ¹⁴C ¹⁶O, ¹²C ¹⁷O, ¹³C ¹⁷O, ¹⁴C ¹⁷O, ¹²C ¹⁸O, ¹³C ¹⁸O, and ¹⁴C ¹⁸O. Calculated transition frequencies based on the fitted parameters were compared with previously reported. A critical analysis of the CO HITRAN and HITEMP data is also presented.