Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: PPM-Extended (PPMX) - a catalogue of positions and proper motions   Aims: We build a catalogue PPM-Extended (PPMX) on the ICRS system which is
complete down to a well-defined limiting magnitude and contains the best
presently available proper motions to be suited for kinematical studies in the
Galaxy.
  Methods: We perform a rigorous weighted least-squares adjustment of
individual observations, spread over more than a century, to determine mean
positions and proper motions. The stellar content of PPMX is taken from GSC 1.2
supplemented by catalogues like ARIHIP, PPM and Tycho-2 at the bright end. All
observations have been weighted according to their individual accuracy. The
catalogue has been screened towards rejecting false entries in the various
source catalogues.
  Results: PPM-Extended (PPMX) is a catalogue of 18,088,920 stars containing
astrometric and photometric information. Its limiting magnitude is about 15.2
in the GSC photometric system. PPMX consists of three parts: a) a survey
complete down to R_U = 12.8 in the magnitude system of UCAC2; b) additional
stars of high-precision proper motions, and c) all other stars from GSC 1.2
identified in 2MASS. The typical accuracy of the proper motions is 2mas/y for
66 percent of the survey stars (a) and the high-precision stars (b), and about
10 mas/y for all other stars. PPMX contains photometric information from
ASCC-2.5 and 2MASS.

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The categories of this paper are: plasm-ph
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The categories of this paper are: gr-qc
1
The categories of this paper are: cs
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The categories of this paper are: q-alg
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The categories of this paper are: econ
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-fin
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The categories of this paper are: hep-th
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The categories of this paper are: supr-con
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The categories of this paper are: alg-geom
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The categories of this paper are: math-ph
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The categories of this paper are: nlin
2
The categories of this paper are: math
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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-ex
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The categories of this paper are: patt-sol