Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: The Cosmic Ray Background as a Tool for Relative Calibration of
  Atmospheric Cherenkov Telescopes
18
The categories of this paper are: econ
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th