Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ole Romer's method still on the stage. The study of two bound eclipsing
  binaries in quintuple system V994 Her   More than three hundred years ago, Ole Romer measured the speed of light only
by observing the periodic shifting of the observed eclipse arrival times of
Jupiter's moons arising from the varying Earth-Jupiter distance. The same
method of measuring the periodic modulation of delays is still used in
astrophysics. The ideal laboratories for this effect are eclipsing binaries.
The unique system V994 Her consists of two eclipsing binaries orbiting each
other. However, until now it was not certain whether these are gravitationally
bound and what their orbital period is. We show that the system is in fact
quintuple and the two eclipsing binaries are orbiting each other with period
about 6.3 years. This analysis was made only from studying the periodic
modulation of the two periods, when during the periastron passage one binary
has an apparently shorter period, while the other one longer, exactly as
required by a theory. Additionally, it was found that both inner eclipsing
pairs orbit with slightly eccentric orbits undergoing a slow apsidal motions
with a period of the order of centuries.

23
The categories of this paper are: solv-int
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
25
The categories of this paper are: patt-sol
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
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The categories of this paper are: acc-phys
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-ex
27
The categories of this paper are: comp-gas
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The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph