Thioketene (H2CCS) was the target of two recent searches, one successful, one unsuccessful. In 2019,
McGuire et al. reported a search
for thioketene toward ten sources, including Sgr B2(N), Orion-KL,
and TMC-1, but they did not find specific rotational transitions
of the compound in any of the sources.
A subsequent search by
Cernicharo et al. reported in 2021
identified 6 rotatational transitions of thioketene toward TMC-1 as observed with the
Yebes 40m telescope.
As Cernicharo et al. noted, the unsuccessful search of McGuire et al. focused on a transition
(120,12-110,11) that requires a temperature of 40 K to
populate rather than lower
energy transitions that are excited at 7 K. (The highest energy transition detected by Cernicharo et al. was