Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Galaxy Spectral Types and Their Applications in the 2dFGRS   The 2dF Galaxy Redshift Survey (2dFGRS) has already measured over 200,000
redshifts of nearby (median redshift z~0.1) galaxies. This is the single
largest set of galaxy spectra ever collected. It allows us to subdivide the
survey into subsets according to the galaxy intrinsic properties. We outline
here a method (based on Principal Component Analysis) for spectrally
classifying these galaxies in a robust and independent manner. In so doing we
develop a continuous measure of spectral type, eta, which reflects the actual
distribution of spectra in the observed galaxy population. We demonstrate the
usefulness of this classification by estimating luminosity functions and
clustering per spectral type.

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The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
7
The categories of this paper are: hep-th
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
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The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
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The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
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The categories of this paper are: funct-an
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The categories of this paper are: comp-gas
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The categories of this paper are: nlin
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The categories of this paper are: dg-ga
3
The categories of this paper are: physics
33
The categories of this paper are: plasm-ph