Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: QSO Selection and Photometric Redshifts with Neural Networks   Baryonic Acoustic Oscillations (BAO) and their effects on the matter power
spectrum can be studied by using the Lyman-alpha absorption signature of the
matter density field along quasar (QSO) lines of sight. A measurement
sufficiently accurate to provide useful cosmological constraints requires the
observation of ~100000 quasars in the redshift range 2.2<z<3.5 over ~8000 deg2.
Such a survey is planned by the Baryon Oscillation Spectroscopic Survey (BOSS)
project of the Sloan Digital Sky Survey (SDSS-III).In practice, one needs a
stellar rejection of more than two orders of magnitude with a selection
efficiency for quasars better than 50% up to magnitudes as large as g ~ 22. To
obtain an appropriate target list and estimate quasar redshifts, we have
developed an Artificial Neural Networks (NN) with a multilayer perceptron
architecture. The input variables are photometric measurements, i.e. the object
magnitudes and their errors in the five bands (ugriz) of the SDSS photometry.
For target selection, we achieve a non-quasar point-like object rejection of
99.6% and 98.5% for a quasar efficiency of, respectively, 50% and 85%. The
photometric redshift precision is of the order of 0.1 over the region relevant
for BAO studies.

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The categories of this paper are: supr-con
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The categories of this paper are: q-bio
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The categories of this paper are: solv-int
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The categories of this paper are: ao-sci
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The categories of this paper are: math-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-alg
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The categories of this paper are: funct-an
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The categories of this paper are: hep-ex
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The categories of this paper are: cond-mat
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The categories of this paper are: nlin
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The categories of this paper are: hep-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
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The categories of this paper are: dg-ga
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The categories of this paper are: gr-qc