Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Parameter degeneracies and (un)predictability of gravitational
  microlensing events   (abridged) Some difficulties in determining the physical properties that lead
to observed anomalies in microlensing light curves, such as the mass and
separation of extra-solar planets orbiting the lens star, or the relative
source-lens parallax, are already anchored in factors that limit the amount of
information available from ordinary events and in the adopted parametrization.
Moreover, a real-time detection of deviations from an ordinary light curve
while these are still in progress can only be done against a known model of the
latter, and such is also required for properly prioritizing ongoing events for
monitoring in order to maximize scientific returns. Despite the fact that
ordinary microlensing light curves are described by an analytic function that
only involves a handful of parameters, modelling these is far less trivial than
one might be tempted to think. A well-known degeneracy for small impacts, and
another one for the initial rise of an event, makes an interprediction of
different phases impossible, while determining a complete set of model
parameters requires the assessment of the fundamental characteristics of all
these phases. While the wing of the light curve provides valuable information
about the time-scale that absorbs the physical properties, the peak flux of the
event can be meaningfully predicted only after about a third of the total
magnification has been reached. Parametrizations based on observable features
not only ease modelling by bringing the covariance matrix close to diagonal
form, but also allow good predictions of the measured flux without the need to
determine all parameters accurately. Campaigns intending to infer planet
populations from observed microlensing events need to invest some time into
acquiring data that allows to properly determine the magnification function.

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The categories of this paper are: hep-ex
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The categories of this paper are: econ
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The categories of this paper are: quant-ph
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The categories of this paper are: stat
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The categories of this paper are: solv-int
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The categories of this paper are: math
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The categories of this paper are: math-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: q-alg
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The categories of this paper are: hep-th
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The categories of this paper are: funct-an
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The categories of this paper are: supr-con
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The categories of this paper are: cs
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The categories of this paper are: chao-dyn
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The categories of this paper are: chem-ph
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The categories of this paper are: cond-mat