Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Extragalactic Large-Scale Structures behind the Southern Milky Way. - I.
  Redshifts Obtained at the SAAO in the Hydra/Antlia Extension   Spectroscopic observations have been carried out for galaxies in the Milky
Way with the 1.9 m telescope of the South African Astronomical Observatory
(SAAO). The galaxies were selected from a deep optical galaxy search covering
266<l<296 |b|<10deg. This is in the extension of the Hydra and Antlia clusters
and in the approximate direction of the dipole anisotropy in the Cosmic
Microwave Back- ground radiation. The galaxies in the SAAO observing program --
one of the three complementary approaches in mapping the 3D galaxy distribution
in the ZOA -- were selected for high central SB and for even distribution over
the search area. The galaxies have magnitudes in the range 14.5<B_J<17.5. Good
S/N redshifts were determined for 115 galaxies. One spectrum confirmed a PN,
and another object (v=57km\s) most likely is galactic as well. The other 25
spectra have low S/N or were dominated by superimposed foreground stars. We do
find evidence for a continuation of the Hydra/Antlia supercluster across the
ZOA to b=-10, making it one of the larger structures (supercluster?) in the
nearby Universe. However, the prominent overdensity unveiled in the galaxy
search in Vela (l~280, b~+6) does not, contrary to what may be expected from
the 2D distribution, blend with the Hydra and Antlia supercluster (v~3000km/s).
The latter seems concentrated at v~6000km/s$. Whether it is related to the
Great Attractor cannot yet be assessed. Another weaker concentration is found
at v~9700k/ms. A distinct overabundance of redshifts around v~16000km/s is
found, corresponding to that of the adjacent dense Shapley (Alpha) region in
the northern galactic hemisphere andto that of the Horologium superclusters in
the southern galactic hemisphere. This might indicate that these two overdensi-
ties are part of a single massive structure, bisected by the Milky Way.

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The categories of this paper are: patt-sol
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The categories of this paper are: funct-an
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The categories of this paper are: atom-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: supr-con
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The categories of this paper are: hep-ph
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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: alg-geom
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The categories of this paper are: adap-org
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The categories of this paper are: comp-gas
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The categories of this paper are: eess
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The categories of this paper are: chao-dyn
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The categories of this paper are: solv-int
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The categories of this paper are: mtrl-th
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The categories of this paper are: cmp-lg