Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Null Geodesics of the Kerr Exterior   The null geodesic equation in the Kerr spacetime can be expressed as a set of
integral equations involving certain potentials. We classify the roots of these
potentials and express the integrals in manifestly real Legendre elliptic form.
We then solve the equations using Jacobi elliptic functions, providing the
complete set of null geodesics of the Kerr exterior as explicit parameterized
curves.

21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
35
The categories of this paper are: mtrl-th
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The categories of this paper are: eess
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The categories of this paper are: comp-gas
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The categories of this paper are: q-fin
9
The categories of this paper are: nlin
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
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The categories of this paper are: plasm-ph
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The categories of this paper are: stat
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The categories of this paper are: patt-sol
3
The categories of this paper are: physics
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The categories of this paper are: cmp-lg
18
The categories of this paper are: econ
10
The categories of this paper are: q-bio