Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Absolute astrometry in the next 50 years   With Gaia in orbit since December 2013 it is time to look at the future of
fundamental astrometry and a time frame of 50 years is needed in this matter. A
space mission with Gaia-like astrometric performance is required, but not
necessarily a Gaia-like satellite. It should be studied whether this can be
obtained within the budget of a medium-size ESA mission. A dozen science issues
for a Gaia successor mission in twenty years, with launch about 2033, are
presented and in this context also other possibilities for absolute astrometry
with milliarcsecond (mas) or sub-mas accuracies are discussed. The three
powerful techniques: VLBI, the MICADO camera on the E-ELT, and the LSST are
described and documented by literature references and by an extensive
correspondence with leading astronomers who readily responded with all the
information I needed. In brief, the two Gaia-like missions would provide an
astrometric foundation for all branches of astronomy from the solar system and
stellar systems, including exo-planet systems, to compact galaxies, quasars and
dark matter (DM) substructures by data which cannot be surpassed in the next 50
years. - In April 2017 ESA selected our proposal Hobbs et al. (2016) for study
of a detector with NIR sensitivity for a Gaia successor mission, called
GaiaNIR.

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The categories of this paper are: plasm-ph
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
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The categories of this paper are: acc-phys
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The categories of this paper are: dg-ga
10
The categories of this paper are: q-bio
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The categories of this paper are: atom-ph
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The categories of this paper are: supr-con
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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: hep-ex
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The categories of this paper are: bayes-an
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The categories of this paper are: chem-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: eess