Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Galaxy interactions in the Hickson Compact Group 88   I present observations of the Hickson Compact Group 88 (HCG88) obtained
during the commissioning of a new 28-inch telescope at the Wise Observatory.
This galaxy group was advertised to be non-interacting, or to be in a very
early interaction stage, but this is not the case. The observations reported
here were done using a "luminance" filter, essentially a very broad R filter,
reaching a low surface brightness level of about 26 mag per square arcsec.
Additional observations were obtained in a narrow spectral band approximately
centered on the rest-frame H-alpha line from the group. Contrary to previous
studies, my observations show that at least two of the major galaxies have had
significant interactions in the past, although probably not between themselves.
I report the discovery of a faint extended tail emerging from the brightest of
the group galaxies, severe isophote twisting and possible outer shells around
another galaxy, and map the HII regions in all the galaxies.

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The categories of this paper are: atom-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: comp-gas
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The categories of this paper are: stat
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The categories of this paper are: solv-int
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: econ
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-lat
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The categories of this paper are: physics
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The categories of this paper are: q-bio
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The categories of this paper are: ao-sci
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The categories of this paper are: cond-mat
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The categories of this paper are: nucl-th