Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Cygnus X region XXIII. Is 18P87 galactic or extragalactic?   The radio source 18P87, previously thought to be a point source, has been
serendipitously found to be resolved into a core-jet geometry in VLA maps. HI
absorption of continuum emission (in data from the Canadian Galactic Plane
Survey) appears in gas with radial velocities > +2 km/s but not in brightly
emitting gas at lower radial velocity. Examination of further archival
observations at radio, infrared and optical wavelengths suggests that the
"obvious" interpretation as a radio galaxy requires a rather unusual object of
this kind and a highly unusual local line of sight. We argue that 18P87 may be
a Galactic object, a local astrophysical jet. If this is correct it could have
arisen from outbursts of a microquasar.

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The categories of this paper are: cs
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The categories of this paper are: chem-ph
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The categories of this paper are: physics
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The categories of this paper are: q-alg
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The categories of this paper are: cond-mat
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-ex
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The categories of this paper are: stat
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The categories of this paper are: q-bio
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The categories of this paper are: hep-th
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-th
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The categories of this paper are: adap-org
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: math-ph