Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 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.

12
The categories of this paper are: nucl-th
28
The categories of this paper are: alg-geom
25
The categories of this paper are: patt-sol
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
18
The categories of this paper are: econ
24
The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys