Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Discovery of three strongly lensed quasars in the Sloan Digital Sky
  Survey   We present the discovery of 3 quasar lenses in the Sloan Digital Sky Survey
(SDSS), selected using two novel photometry-based selection techniques. The
J0941+0518 system, with two point sources separated by 5.46" on either side of
a galaxy, has source and lens redshifts $z_s = 1.54$ and $z_l = 0.343$. The
AO-assisted images of J2211+1929 show two point sources separated by 1.04",
corresponding to the same quasar at $z_s = 1.07,$ besides the lens galaxy and
Einstein ring. Images of J2257+2349 show two point sources separated by 1.67"
on either side of an E/S0 galaxy. The extracted spectra show two images of the
same quasar at redshift $z_s = 2.10$. In total, the two selection techniques
identified 309 lens candidates, including 47 known lenses, and 6 previously
ruled out candidates. 55 of the remaining candidates were observed using NIRC2
and ESI at Keck Observatory, EFOSC2 at the ESO-NTT (La Silla), and SAM and the
Goodman spectrograph at SOAR. Of the candidates observed, 3 were confirmed as
lenses, 36 were ruled out, and 16 remain inconclusive. Taking into account that
we recovered known lenses, this gives us a success rate of at least 50/309
(16%). This initial campaign demonstrates the power of purely photometric
selection techniques in finding lensed quasars. Developing and refining these
techniques is essential for efficient identification of these rare lenses in
ongoing and future photometric surveys.

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The categories of this paper are: gr-qc
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The categories of this paper are: cond-mat
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The categories of this paper are: chao-dyn
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The categories of this paper are: funct-an
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The categories of this paper are: cs
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The categories of this paper are: ao-sci
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The categories of this paper are: stat
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The categories of this paper are: hep-ex
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The categories of this paper are: atom-ph
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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: chem-ph
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The categories of this paper are: math
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-lat
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The categories of this paper are: alg-geom