Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Calibration of the Barnes-Evans relation using interferometric
  observations of Cepheids
7
The categories of this paper are: hep-th
0
The categories of this paper are: hep-ph
17
The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math
16
The categories of this paper are: stat
18
The categories of this paper are: econ
36
The categories of this paper are: cmp-lg
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org