A five-minute observation of OMC1 showing spectral lines in a 1.8 GHz wide window centred at 347.3 GHz. From left to right the three strongest lines are the SO 89-78 , SO2 191,19-180,18, and SiO 8-7 transitions. The SO and SO2 abundances are significantly enhanced in OMC1 due to shock-driven chemistry.