One of this year's newly discovered molecules is the ketenyl radical, HCCO, which was detected by Agúndez et al. toward two dark clouds, the protostar L433 and the starless core Lupus-1 (which has also been found to contain abundant interstellar anions). The IRAM 30m telescope was used for the astronomical observations. To date, this detection has not been confirmed by subsequent observations. Turner & Sears searched for HCCO in the dark molecular cloud TMC-1 in the late 1980s without success.

The ketenyl (or ethynyloxy) radical is a near prolate asymmetric top (κ=-0.99). Its rotational spectrum was characterized by Endo & Hirota in work published in 1987. The Cologne Database lists 348 lines for HCCO.