Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Unique Determination of the Physical Parameters of Individual MACHOs
  from Astrometric Parallax Measurements   The Einstein time scale, which is the only information obtained from current
microlensing experiments, results from a complicated combination of the lens
parameters that we want to determine. Of the methods for breaking the lens
parameter degeneracy, the most promising and generally applicable method is to
measure the lens parallax from simultaneous observations of a lensing event
from the ground and a heliocentric satellite (Gould 1994). However, the elegant
idea of parallax measurement, which was proposed to resolve the lens parameter
degeneracy, paradoxically suffers from its own degeneracy due to the ambiguity
of the source star trajectory. In this paper, we propose to measure the lens
parallax astrometrically by mounting an interferometer instead of a photometer
in the proposed parallax satellite. By simultaneously measuring the source star
centroid shifts from a geocentric and an additional heliocentric satellite, one
can determine the lens parallax without ambiguity. If the already planned {\it
Space Interferometry Mission} will be used as one of the satellites, one simply
needs to replace the photometer in the parallax satellite with an instrument
for astrometric observation. In addition, since the proposed method can measure
both the lens parallax and the proper motion at the same time, one can
completely break the lens parameter degeneracy, and therefore uniquely
determine the physical parameters of individual lenses.

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The categories of this paper are: alg-geom
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The categories of this paper are: comp-gas
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-ex
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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: acc-phys
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The categories of this paper are: hep-lat
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The categories of this paper are: cs
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The categories of this paper are: nucl-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: ao-sci
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The categories of this paper are: q-fin
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The categories of this paper are: atom-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: mtrl-th