A CSO Search for $l$-C${}_3$H${}^{+}$: Detection in the Orion Bar PDR

The results of a Caltech Submillimeter Observatory (CSO) search for $l$-C${}_3$H${}^{+}$, first detected by Pety et al. (2012) in observations toward the Horsehead photodissociation region (PDR), are presented. A total of 39 sources were observed in the 1 mm window. Evidence of emission from $l$-C${}_3$H${}^{+}$ is found in only a single source - the Orion Bar PDR region, which shows a rotational temperature of 178(13) K and a column density of 7(2) x ${10}^{11}$ cm${}^{-2}$. In the remaining sources, upper limits of ~10${}^{11}-{10}^{13}$ cm${}^{-2}$ are found. These results are discussed in the context of guiding future observational searches for this species.