Rotational spectroscopy of lutetium monoxide, LuO

► LuO prepared by laser ablation of Lu metal in the presence of O2 in Ar. ► Fourier transform microwave spectrum of LuO (X2Σ+) in a pulsed Ar jet. ► Precise spectroscopic constants and geometry of LuO (X2Σ+). ► Data for astrophysical searches for LuO.