Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: ALFALFA: an Exploration of the z=0 HI Universe   The Arecibo Legacy Fast ALFA (ALFALFA) Survey is a program aimed at obtaining
a census of HI-bearing objects over a cosmologically significant volume of the
local Universe. It will cover 7074 square degrees of the high latitude sky
accessible with the Arecibo 305m telescope, using the 7-beam feed L-band feed
array (ALFA). Started in February 2005, as of Summer of 2007 survey
observations are 44\% complete. ALFALFA offers an improvement of about one
order of magnitude in sensitivity, 4 times the angular resolution, 3 times the
spectral resolution, and 1.6 times the total bandwidth of HIPASS. Although it
will cover only one quarter the sky solid angle surveyed by HIPASS, ALFALFA
will detect approximately six times as many sources, with a median depth of 110
Mpc. Preliminary results of ALFALFA are presented, with emphasis on those
related with the Virgo cluster.

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The categories of this paper are: patt-sol
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The categories of this paper are: physics
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The categories of this paper are: hep-th
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-lat
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The categories of this paper are: q-alg
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The categories of this paper are: nucl-th
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The categories of this paper are: cs
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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: math
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The categories of this paper are: dg-ga
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The categories of this paper are: q-fin
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The categories of this paper are: atom-ph
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The categories of this paper are: nlin
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The categories of this paper are: q-bio