Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: General relativistic formulas for mass and spin of a Kerr black hole in
  terms of redshifts and orbital parameters   We derive closed formulas for the mass and spin parameters of a Kerr black
hole in terms of a minimal quantity of observational data: the red-/blue-shifts
of photons emitted by massive particles (stars) moving on geodesics around the
black hole and their respective orbital radius. It turns out that given a set
of two (three) stars revolving around the black hole, these formulas involve
just eight (twelve) observational data. For the case of a single star orbiting
the black hole we need a minimal set of four observational measurements to
analytically determine both parameters.

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The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
0
The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
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The categories of this paper are: bayes-an
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The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg