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abstract
An emission line observed at 203 $\mu$m in Orion A, DR 21, and W51 is tentatively attributed to emission from the second rotationally excited state (F2, N=2, J=3/2) of CH. Emission from this state has not previously been detected. In conjunction with a limit placed on a companion transition at 204 $\mu$m in Orion A, this detection would suggest collisional excitation of the emitting gas since the emitting state is of the same parity as the ground state and thus not radiatively coupled to it.
