Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Seeing Galaxies Through Thick and Thin: II. Direct Measures of
  Extinction in Spiral Disks Through Spectroscopy of Overlapping Galaxies   We use slit spectroscopy of overlapping pairs of galaxies to directly
determine the extinction in disks of foreground spiral galaxies. The Doppler
shifts of pair members are determined via cross-correlation and their relative
correlation amplitudes are used to separate their contributions to the combined
spectra in regions of overlap. This spectroscopic approach is less subject to
stringent symmetry constraints than our previous purely photometric analyses.
Extinctions of foreground members were obtained for 6 of the candidates in our
sample of 18 mostly spiral/spiral pairs, when the signal to noise and velocity
difference were suitable. In agreement with our previous imaging results, we
find that the extinction in interarm regions is very modest, typically A_B=0.1
mag (corrected to face on), while spiral arms exhibit higher extinctions of 0.3
mag.

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The categories of this paper are: q-fin
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The categories of this paper are: ao-sci
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The categories of this paper are: solv-int
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: comp-gas
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The categories of this paper are: cmp-lg
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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: econ
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-th
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The categories of this paper are: cond-mat
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The categories of this paper are: dg-ga
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The categories of this paper are: nlin
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The categories of this paper are: stat