Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Dynamics of the Merging Galaxy Cluster System A2256: Evidence for a
  New Subcluster   We present 236 new radial velocities of galaxies in the cluster A2256
measured with the WIYN Hydra multi-object spectrograph. Combined with the
previous work of Fabricant, Kent, and Kurtz (1989), we have velocities for a
total of 319 galaxies of which 277 are cluster members. In addition to the new
radial velocities, we present a 3x3 image mosaic in the R band of the central
19'x19' region of A2256, from which we obtained photometry for 861 galaxies.
These data provide strong evidence for a merger event between two groups. In
addition, we present evidence for the presence of a third group, on the outer
reaches of the system, that is just now beginning to merge with the system.

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The categories of this paper are: ao-sci
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The categories of this paper are: plasm-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: q-bio
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The categories of this paper are: mtrl-th
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The categories of this paper are: acc-phys
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The categories of this paper are: eess
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The categories of this paper are: math-ph
3
The categories of this paper are: physics
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The categories of this paper are: hep-th
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The categories of this paper are: econ
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The categories of this paper are: cond-mat
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The categories of this paper are: adap-org
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The categories of this paper are: alg-geom
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-th