Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Galaxy Zoo : Morphologies derived from visual inspection of galaxies
  from the Sloan Digital Sky Survey   In order to understand the formation and subsequent evolution of galaxies one
must first distinguish between the two main morphological classes of massive
systems: spirals and early-type systems. This paper introduces a project,
Galaxy Zoo, which provides visual morphological classifications for nearly one
million galaxies, extracted from the Sloan Digital Sky Survey (SDSS). This
achievement was made possible by inviting the general public to visually
inspect and classify these galaxies via the internet. The project has obtained
more than 40,000,000 individual classifications made by ~100,000 participants.
We discuss the motivation and strategy for this project, and detail how the
classifications were performed and processed. We find that Galaxy Zoo results
are consistent with those for subsets of SDSS galaxies classified by
professional astronomers, thus demonstrating that our data provides a robust
morphological catalogue. Obtaining morphologies by direct visual inspection
avoids introducing biases associated with proxies for morphology such as
colour, concentration or structual parameters. In addition, this catalogue can
be used to directly compare SDSS morphologies with older data sets. The
colour--magnitude diagrams for each morphological class are shown, and we
illustrate how these distributions differ from those inferred using colour
alone as a proxy for morphology.

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The categories of this paper are: q-alg
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The categories of this paper are: econ
5
The categories of this paper are: gr-qc
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The categories of this paper are: hep-lat
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The categories of this paper are: nlin
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The categories of this paper are: alg-geom
2
The categories of this paper are: math
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The categories of this paper are: nucl-th
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The categories of this paper are: math-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: stat
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The categories of this paper are: plasm-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: cs
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The categories of this paper are: mtrl-th
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The categories of this paper are: funct-an