Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Determining the extragalactic extinction law with SALT   We present CCD imaging observations of early-type galaxies with dark lanes
obtained with the Southern African Large Telescope (SALT) during its
performance-verification phase. We derive the extinction law by the
extragalactic dust in the dark lanes in the spectral range 1.11mu m^{-1} <
lambda^{-1} < 2.94 mu m^{-1} by fitting model galaxies to the unextinguished
parts of the image, and subtracting from these the actual images. We find that
the extinction curves run parallel to the Galactic extinction curve, which
implies that the properties of dust in the extragalactic enviroment are similar
to those of the Milky Way. The ratio of the total V band extinction to the
selective extinction between the V and B bands is derived for each galaxy with
an average of 2.82+-0.38, compared to a canonical value of 3.1 for the Milky
Way. The similar values imply that galaxies with well-defined dark lanes have
characteristic dust grain sizes similar to those of Galactic dust.

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The categories of this paper are: q-fin
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The categories of this paper are: math-ph
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The categories of this paper are: q-bio
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The categories of this paper are: eess
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The categories of this paper are: plasm-ph
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: mtrl-th
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The categories of this paper are: supr-con
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The categories of this paper are: hep-th
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The categories of this paper are: dg-ga
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The categories of this paper are: solv-int
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The categories of this paper are: physics
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: cond-mat