Cyclopropenone, c-H₂C₃O, has been detected with the 100 m Greenbank telescope toward Sgr B2(N) – largely in absorption:
J. M. Hollis, A. J. Remijan, P. R. Jewell, and F. J. Lovas,
Cyclopropenone (c-H₂C₃O) a new Interstellar Ring Molecule
Astrophys. J. 642, 933–939 (2006).
The molecule was detected in the six lower energy a-type transitions between 8 and 45 GHz. It was not seen in two higher energy transitions. This and the appearance largely in absorption suggests the molecule to be present in the colder and less dense envelope of Sgr B2(N). The molecule can be viewed as a derivative of the ubiquitous, small aromatic cyclopropenylidene, c-C₃H₂.

J.-C. Loison, M. Agúndez, N. Marcelino, V. Wakelam, K. M. Hickson, J. Cernicharo, M. Gerin, E. Roueff, and M. Guélin
reported on
The interstellar chemistry of H₂C₃O isomers
Mon. Not. R. Astron. Soc. 456, 4101–4110 (2016).
The molecule was detected in the 7_1,6 – 6_1,5 transition near 103.1 GHz toward four of seven dark clouds employing the IRAM 30 m telescope. The four sources are TMC-1, B1-b, L483, and Lupus-1A.

Contributor(s): H. S. P. Müller; 02, 2006; 02, 2016