The observation of tricarbon (C₃) in the circumstellar shell IRC +10216 by was reported by Hinkle et al. in 1988. Unlike many identifications, which are made by matching features from the pure rotational spectrum, the detection of C₃ involved its coupled vibration-rotation spectrum. Further sources where tricarbon has been seen include the protoplanetary nebula IRAS 22272 + 5435 and toward HD 210121. It has also been detected by means of a pure vibrational line in Sgr B2 and IRC +10216 by Cernicharo et al.

Tricarbon was also one of the earliest species to be observed in comets, as reported by Huggins in 1881. This was evidentally forgotten for many years.