  More than 130 pure rotational transitions of $^{46}$TiO, $^{47}$TiO,
$^{48}$TiO, $^{49}$TiO, $^{50}$TiO, and $^{48}$Ti$^{18}$O are recorded using a
high-resolution mm-wave supersonic jet spectrometer in combination with a laser
ablation source. For the first time a mass-independent Dunham-like analysis is
performed encompassing rare titanium monoxide isotopologues, and are compared
to results from high-accuracy quantum-chemical calculations. The obtained
parametrization reveals for titanium monoxide effects due to deviations from
the Born-Oppenheimer approximation. Additionally, the dominant titanium
properties enable an insight into the electronic structure of TiO by analyzing
its hyperfine interactions. Further, based on the mass-independent analysis,
the frequency positions of the pure rotational transitions of the short lived
rare isotopologue $^{44}$TiO are predicted with high accuracy, i.e., on a
sub-MHz uncertainty level. This allows for dedicated radio-astronomical
searches of this species in core-collapse environments of supernovae.
