Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Properties of Planetary Caustics in Gravitational Microlensing   Although some of the properties of the caustics in planetary microlensing
have been known, our understanding of them is mostly from scattered information
based on numerical approaches. In this paper, we conduct a comprehensive and
analytic analysis of the properties of the planetary caustics, which are one of
the two sets of caustics in planetary microlensing, those located away from the
central star. Under the perturbative approximation, we derive analytic
expressions for the location, size, and shape of the planetary caustic as a
function of the star-planet separation and the planet/star mass ratio. Based on
these expressions combined with those for the central caustic, which is the
other set of caustics located close to the central star, we compare the
similarities and differences between the planetary and central caustics. We
also present the expressions for the size ratio between the two types of
caustics and for the condition of the merging of the two types of caustics.
These analytic expressions will be useful in understanding the dependence of
the planetary lensing behavior on the planet parameters and thus in
interpreting the planetary lensing signals

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The categories of this paper are: funct-an
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The categories of this paper are: chao-dyn
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The categories of this paper are: comp-gas
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The categories of this paper are: nucl-ex
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The categories of this paper are: math-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-ph
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The categories of this paper are: econ
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The categories of this paper are: plasm-ph
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The categories of this paper are: eess
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The categories of this paper are: solv-int
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The categories of this paper are: atom-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: cmp-lg