Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The retrograde orbit of the globular cluster FSR1758 revealed with Gaia
  DR2   We report the first radial velocity measurements of the recently identified
globular cluster FSR1758. From the two member stars with radial velocities from
the Gaia Radial Velocity Spectrograph reported in Gaia DR2, we find FSR1758 has
a radial velocity of $227\pm1$ km/s. We also find potential extra-tidal star
lost from the cluster in the surrounding 1~deg. Combined with Gaia proper
motions and photometric distance estimates, this shows that FSR1758 is on a
very retrograde, radial orbit with an pericentre of $3.8_{-0.9}^{+0.9}$ kpc, an
apocentre of $16_{-5}^{+8}$ kpc, and eccentricity of $0.62_{-0.04}^{+0.05}$.
Although it is currently at a Galactocentric distance of $3.8_{-0.9}^{+0.9}$
kpc --- at the edge of the bulge --- it is an intruder from the halo. We
investigate whether a reported `halo' of stars around FSR1758 is related to the
cluster, and find that most of these stars are likely foreground dwarf stars.
We conclude that FSR1758 is not a dwarf galaxy, but rather a globular cluster.

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The categories of this paper are: hep-th
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The categories of this paper are: ao-sci
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The categories of this paper are: q-bio
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The categories of this paper are: nlin
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The categories of this paper are: dg-ga
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The categories of this paper are: math
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The categories of this paper are: plasm-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: nucl-ex
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The categories of this paper are: gr-qc
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The categories of this paper are: bayes-an
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The categories of this paper are: math-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: q-alg
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The categories of this paper are: mtrl-th
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The categories of this paper are: q-fin