Line spectrum in the vicinity of the υ = 0, J = 31/2 rotational level of OH and of two nearby TiO₂ transitions observed in the 284.00 to 284.40 GHz range toward omi Cet (Mira). The expected F' – F'' = 15–15 and 16 – 16 hyperfine transitions of OH in the J = 31/2 Λ-doublet are indicated with two light green vertical lines at the expected frequencies. The two TiO₂ lines correspond to the 27(7, 21) – 27(6, 22) and 21(1, 21) – 26(0, 20) transitions at 284.0943 and 284.3719 GHz, respectively. Spectrum extracted from a 0.″25×0.″20 region containing all the OH emission.