Confirmation of interstellar acetone

We present new observations of interstellar acetone [(CH₃) ₂CO] from both the NRAO 12 m and the BIMA array. We report NRAO 12 m detections of 13 new acetone emission features that can be assigned to 20 acetone transitions. These assignments are based on the measured and calculated frequencies in 2002 of Groner and coworkers, and they confirm the interstellar acetone identification in 1987 by Combes and co-workers. In addition, our BIMA array observations show that acetone emission is concentrated in the vicinity of the hot molecular core Sgr B2 (N-LMH). The beam-averaged column density for acetone is 〈N_T〉 = 2.9(3) × 10¹⁶ cm ^-2. This value is consistent with the 1990 conclusions of Herbst, Giles, & Smith that the observed acetone abundance is too high to be explained by gas-phase synthesis reactions.