Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quasar Lenses and Galactic Streams: Outlier Selection and GAIA Multiplet
  Detection   I describe two novel techniques originally devised to select strongly lensed
quasar candidates in wide-field surveys. The first relies on outlier selection
in optical and mid-infrared magnitude space; the second combines mid-infrared
colour selection with GAIA spatial resolution, to identify multiplets of
objects with quasar-like colours. Both methods have already been applied
successfully to the SDSS, ATLAS and DES footprints: besides recovering known
lenses from previous searches, they have led to new discoveries, including
quadruply lensed quasars, which are rare within the rare-object class of quasar
lenses. As a serendipitous by-product, at least four candidate Galactic streams
in the South have been identified among foreground contaminants. There is
considerable scope for tailoring the WISE-GAIA multiplet search to stellar-like
objects, instead of quasar-like, and to automatically detect Galactic streams.

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The categories of this paper are: alg-geom
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The categories of this paper are: solv-int
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The categories of this paper are: chao-dyn
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The categories of this paper are: econ
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The categories of this paper are: chem-ph
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The categories of this paper are: q-alg
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The categories of this paper are: physics
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The categories of this paper are: funct-an
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The categories of this paper are: nlin
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The categories of this paper are: cond-mat
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The categories of this paper are: mtrl-th
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The categories of this paper are: eess
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The categories of this paper are: nucl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: cs
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The categories of this paper are: bayes-an