Microwave Emission of the 211?212 Rotational Transition in Interstellar Acetaldehyde

The 211?212 transition of acetaldehyde at 3195 ·167 MHz has been observed in emission in SgrB2 with the Parkes 64 m telescope. Comparison of the intensities of the 110---> 11 and 211--->212 emission lines suggests that both transitions may be inverted.