Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: An XMM-Newton observation of Ark 120: the X-ray spectrum of a `bare'
  Seyfert 1 nucleus
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
20
The categories of this paper are: acc-phys
19
The categories of this paper are: eess
21
The categories of this paper are: adap-org
14
The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an