Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: SDSSJ102111.02+491330.4: A Newly Discovered Gravitationally Lensed
  Quasar   We report follow-up observations of two gravitational lens candidates
identified in the Sloan Digital Sky Survey (SDSS) dataset. We have confirmed
that SDSS J102111.02+491330.4 is a previously unknown gravitationally lensed
quasar. This lens system exhibits two images of a $z = 1.72$ quasar, with an
image separation of $1{\farcs}14 \pm 0.04$. Optical and near-IR imaging of the
system reveals the presence of the lensing galaxy between the two quasar
images. Observations of SDSS J112012.12+671116.0 indicate that it is more
likely a binary quasar than a gravitational lens. This system has two quasars
at a redshift of $z = 1.49$, with an angular separation of $1{\farcs}49 \pm
0.02$. However, the two quasars have markedly different SEDs and no lens galaxy
is apparent in optical and near-IR images of this system. We also present a
list of 31 SDSS lens candidates which follow-up observations have confirmed are
\textit{not} gravitational lenses.

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The categories of this paper are: dg-ga
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: plasm-ph
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The categories of this paper are: physics
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The categories of this paper are: q-fin
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-th
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The categories of this paper are: eess
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The categories of this paper are: cmp-lg
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The categories of this paper are: chao-dyn
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The categories of this paper are: math
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The categories of this paper are: econ
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The categories of this paper are: ao-sci
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The categories of this paper are: acc-phys
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The categories of this paper are: adap-org