Part of the terahertz spectrum of CH₃¹⁷OH showing a large portion of the E symmetry v_t = 2 K_a = 3 ← 2 Q-branch. Selected J values are indicated. Two stronger A symmetry v_t = 0 transitions are indicated by their quantum numbers given in blue. A strong E symmetry v_t = 0 transition of CH₃¹⁶OH is also indicated with quantum numbers in black. Four weaker transitions of CH₃¹⁷OH are marked with blue plus signs.