The discovery of the thioketenyl radical (HCCS) was reported in 2021 by Cernicharo and co-workers toward TMC-1, which they dubbed in their title as "the starless core sulfur factory." The observations were made with the Yebes 40m telescope and the IRAM 30m telescope. While only one transition of HCCS was detected, it included the strongest hyperfine components. The detection employed the rotational spectrum meaured by Kim and co-workers, including the hyperfine constants. The detection of HCCS has not yet been confirmed with further observations nor has it been observed in other sources.